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SIMNRA User's Guide - Max-Planck

1. 93 100 accuracy O 100 step width control 100 geometrical st ver gf rete EEN 16 geometrical straggling 103 in compounds 068 103 multiple scattering 21 107 108 non statistical broadening 94 nuclear energy loss straggling 103 Bohr theory 103 Pa Dari 94 plural scattering 21 107 110 Symon ii 94 Tschalar ssec ckoetotOE ti CR ake YR 94 Vavilov Theatre 94 Yang theory s 23 96 97 Substrate roughness see Surface roughness Surface roughness 111 124 layer roughness 29 30 111 116 number of steps ssessss 26 parameter for calculation 26 rough film see layer roughness rough substrate see substrate roughness substrate roughness 29 30 116 124 SYMON ET see Straggling T Target MENU es rodaron 28 32 A A 32 A pt E pe ED ankai 28 Time of flight detector see Detector Toolbar sssseee o 5 56 Tools men dmca ER data read r se si n canes 53 integrate spectrum 53 nearest elements sess 53 Top electrode see Detector Tschalaf ize yp ass see Straggling U Uninstallation 3 Universal potential 000 87 Userdll eri sos crianza dobra 61 V VavilOV ev e dee EE EN see Straggling VETSION m ii Version history ss se
2. Wait 1000 ms May be necessary for the server to start Sleep 1000 Open a NRA file Result App Open c temp test nra Calculate a spectrum Result App CalculateSpectrum Save the NRA file Result App SaveAs c temp test nra End 201 A OLE automation reference Sample program in Visual Basic Script showing the use of the OLE automation objects Create the application object Set App CreateObject Simnra App Wait 1000 ms May be necessary for the server to start WScript Sleep 1000 Open a NRA file Result App Open c temp test nra Calculate a spectrum Result App CalculateSpectrum Save the NRA file Result App SaveAs c temp test nra Sample program in Visual Basic Script showing the use of the Fit object Create the application object Set App CreateObject Simnra App Create the fit object Set Fit CreateObject Simnra Fit Wait 1000 ms May be necessary for the server to start WScript Sleep 1000 Open a NRA file Result App Open c temp test nra Fit thickness and composition of layer number 2 Fit LayerNr 2 Fit LayerThickness True Fit LayerComposition True One fit region from channel 100 to 200 Fit NumberOfRegions 1 Fit RegionMinChannel 1 100 Fit RegionMaxChannel 1 200 Perform the fit Result App FitSpectrum Sample program in Visual Basic Script showing how to add layers and elements 2
3. 10000 Fast model 1000 Counts 100 10 1 300 400 500 600 700 Channel Figure 4 31 Comparison of the Accurate and Fast models for pile up from a single peak Accurate model with pile up rejector PUR on and off Pulse rise time 1 us pair resolution time 0 3 us Fast model fudge time 0 3 us 135 4 Physics e Experimental No pile up Accurate Fast Counts 0 200 400 600 Channel Figure 4 32 2 MeV He backscattered from Au 0 165 The experimental spectrum was measured with a Canberra 9660 DSP filter rise time 0 5 us filter flat top 0 1 us pile up rejector enabled 6 5 dead time Simulated spectra without pile up accurate model with 0 44 us rise time according to Table 3 1 and 0 35 us PUR pair resolution time fast model with T 0 32 us 136 5 Examples his chapter gives several examples for the abilities of SIMNRA All backscattering spectra were measured at the IPP Garching at a scattering angle 0 165 The solid angle of the detector was 1 08 x 10 sr A standard surface barrier detector with a nominal energy resolution of 15 keV FWHM was used 5 1 RBS Rutherford cross sections Figure 5 1 shows the measured and simulated spectra for 1 0 MeV He incident ions on a gold layer with a thickness of about 100 nm on top of silicon The simulated spectrum fits the measured data very well The low background between the Si edge and the
4. 0 01321 e0 21226 9 19593 0 5 RAG Sn 88 4 Physics for e 30 and Ine 4 47 2 for e gt 30 e is the reduced energy and is given by 32 53 M E 4 48 Z Z M Mp 22 29 Nuclear stopping is only important at incident energies E lt 100 keV at higher energies nuclear stopping becomes negligible Heavy ions The electronic stopping power of heavy ions in all elements is derived from the stopping power of protons using Brandt Kitagawa theory 5 35 The formalism is described in detail in ref 5 a short overview is given in 35 Fermi velocities of all target elements are stored in the file SCOEE95A a small correction to the Fermi velocity in the file SCOEE95B The ion s screening length A as a function of fractional charge is stored in the file SCOEE95B Nuclear stopping for incident heavy ions is calculated with the universal ZBL potential from ref 5 The formalism is the same as for He ions see Equation 4 45 to Equation 4 48 For Zi and M the ions nuclear charge and mass respectively have to be used The nuclear stopping component for heavy ions may be large and cannot be neglected Differences between SIMNRA and SRIM 97 The program SRIM formerly TRIM by J Ziegler is a widely used program for stopping power and range calculations If Ziegler Biersack stopping is selected SIMNRA uses the same stopping power routines and input data as SRIM 97 for elemental targets The routines for
5. Rescale x Axis Scales the x axis to minimum and maximum of all visible spectra Rescale y Axis Scales the y axis to minimum and maximum of all visible spectra Unzoom Undo all zoom operations x Axis Scale the x axis manually by entering the axis minimum and maximum set logarithmic x axis Same as a double click with the left mouse button on the x axis y Axis Scale the y axis manually by entering the axis minimum and maximum set logarithmic y axis Same as a double click with the left mouse button on the y axis Legend Allows to alter the text of the legend Same as a double click with the left mouse button on the legend Delete Experimental Data Deletes the experimental data from the plot Delete Simulated Data Deletes all simulated data from the plot Zooming into the plot To zoom into the plot click with the left mouse button into the upper left corner of the range you want to zoom in Keep the mouse button down and tear a rectangle to the lower right corner of the zooming range Panning Click with the right mouse button into the plot keep the mouse button down and move the mouse Zooming out Click with the left mouse button into the plot Keep the mouse button down and move the mouse towards the upper left corner Or use Plot Unzoom 55 3 Using SIMNRA 3 12 Options menu Create Reaction List SIMNRA uses a file named CRSEC LST in the cross sections directory to know which cross section data are ava
6. smooth Counts a u 1000 1200 1400 1600 1800 Energy keV Figure 4 17 Calculated energy spectra for 2 MeV He backscattered from a smooth and rough gold layers with mean thickness d 1 x 10 Au atoms cm and different roughnesses with standard deviation c The film thickness distributions are shown in Figure 4 16 Incident angle a 0 scattering angle 165 Ey marks the energy at which the low energy edge has decreased to its half height 114 4 Physics e Experiment 1000 Simulation Smooth Simulation Rough 500 Counts 200 400 600 Channel Figure 4 18 1 5 MeV He backscattered at 165 from a rough Ni film with a mean thickness of 2 17 x 10 Ni atoms cm on carbon substrate Dots Experimental data Dashed line Simulation assuming a smooth Ni layer Solid line Simulation assuming a rough Ni layer with roughness o 2 12 x 107 Ni atoms cm in the simulation by a mean Ni layer thickness of 2 17 x 10 Ni atoms cm 238 nm and a roughness with standard deviation o 2 12 x 1077 Ni atoms cm 23 nm solid line The experimental data are not well reproduced by the spectrum of a smooth Ni layer dashed line The roughness of the Ni film was determined from line scans with a profiler The roughness distribution i e the deviation of the actual surface from the leveled one was approximately Gaussian For small values of o d a Gaussian and a Gamma distribution cannot be distinguished see Fig
7. Energy Get Set Property Energy Double Description Energy of incident ions keV Related Properties and Methods Setup Beamspread 165 LiveTime Get Set Property LiveTime Double Description Live time of a measurement s Related Properties and Methods Setup LTCorrection 168 Setup RealTime 169 167 A OLE automation reference LTCorrection Get Set Property LTCorrection Boolean Description True if a live time correction is applied else False Related Properties and Methods Setup LiveTime 167 Setup RealTime 169 ParticlesSr Get Set Property ParticlesSr Double Description Number of incident particles times solid angle sr PUCalculation Get Set Property PUCalculation Boolean Description True if pile up is calculated else False Related Properties and Methods Setup PUROn 169 Setup PURResolution 169 Setup RiseTime 170 PUROn Get Set Property PUROn Boolean 168 A OLE automation reference Description True if a pile up rejector was used else False See section 3 6 2 for details Related Properties and Methods Setup PUCalculation 168 Setup PURResolution 169 Setup RiseTime 170 PURResolution Get Set Property PURResolution Double Description Pile up rejector pair resolution time us See section 3 6 2 for details Related Properties and Methods Setup PUCalculation 168 Setup PUROn 169 Setup RiseTime 170 RealTime Get Set Pr
8. SIMNRA User s Guide Matej Mayer Max Planck Institut f r Plasmaphysik Boltzmannstr 2 D 85748 Garching Germany email Matej Mayer ipp mpg de Tel 49 89 32991639 Fax 49 89 32992279 www simnra com This manual describes SIMNRA version 6 06 O Max Planck Institut f r Plasmaphysik 1997 2011 Additional publications about SIMNRA The first should be used as general reference for the program M Mayer SIMNRA User s Guide Report IPP 9 113 Max Planck Institut f r Plasmaphysik Garching Germany 1997 M Mayer SIMNRA a Simulation Program for the Analysis of NRA RBS and ERDA Pro ceedings of the 15th International Conference on the Application of Accelerators in Research and Industry J L Duggan and I L Morgan eds American Institute of Physics Conference Proceedings 475 p 541 1999 W Eckstein and M Mayer Rutherford Backscattering from layered Structures beyond the Single Scattering Model Nucl Instr Meth B153 1999 337 M Mayer Ion Beam Analysis of Rough Thin Films Nucl Instr Meth B194 2002 177 M Mayer K Arstila K Nordlund E Edelmann and J Keinonen Multiple scattering of MeV ions Comparison between the analytical theory and Monte Carlo and molecular dynamics simulations Nucl Instr Meth B249 2006 823 Contents Contents ETT iii Registration and payment information vii Product license dgreement ei A s dee ws ee ix Version HISTO PET X 1 Overview 1 LA eege ti
9. ooooooooccccncmm x Solid state detector see Detector Spectrum data EE 8 ASC ee Eege dacs 8 CAM file lege coeds ee pex Ne 8 Ganberta or mes Rt ag 8 A neni och aie weavers EAEE 8 Index 219 ISI 8 MCGERD 14 2 RR bg ar 8 A b Raro PE FOR E Re edis 8 RUMP pret a Ro More os tee ies 9 user defined ss 8 61 WHINE ENEE a EIERE aes 8 SIM 5s estere I ERR see Stopping power Stopping power sss 22 85 91 Andersen Ziegler 22 85 heavy ions eee eee eee 87 Heliu enge O 86 Drogen bereet ree e Bac 85 nuclear stopping 85 87 Bragg s rule ssuss 29 90 calculation esche Se See UR oke 48 cores and bonds model 90 correction factor 29 in compounds usueuss 90 KKK stopping s 22 90 SRIM tisse Serrat d 3 22 56 66 90 download 0 cece eee eee 66 installation 66 program directory 56 66 trouble shooting 66 e EEN 22 89 User defined 22 08 Ziegler Biersack 22 87 heavy ions seis devs me e REA TES 89 heliuti i oio etre RELIER 88 hydrogen 87 nuclear stopping 88 89 Straggling i e eb Ee dd eda nn 93 105 Bohr theory 23 94 95 charge state fluctuations 96 97 CHU theory sicario deg E 23 03 electronic energy loss
10. Description Specifies if dual scattering is calculated ElementSpectra Get Set Property ElementSpectra Boolean 173 A OLE automation reference Description Specifies if individual spectra for each element in the target are calculated Related Properties and Methods Calc IsotopeSpectra 175 EMin Get Set Property EMin Double Description Cutoff energy keV HighEnergyStopping Get Set Property HighEnergyStopping Boolean Description Selects if high energy stopping power data are used or not This switch is only used together with the stopping power data by Andersen Ziegler and has no influence if Ziegler Biersack stopping is selected See subsection 3 6 3 for more details Related Properties and Methods Calc ZBStopping 178 Isotopes Get Set Property Isotopes Boolean Description Specifies if isotopes are taken into account 174 A OLE automation reference IsotopeSpectra Get Set Property IsotopeSpectra Boolean Description Specifies if individual spectra for each isotope in the target are calculated Related Properties and Methods Calc ElementSpectra 174 LogFile Get Set Property LogFile Boolean Description Specifies if a log file SIMNRA LOG with additional information about the calcu lation is created MultipleScattering Get Set Property MultipleScattering Boolean Description Specifies if multiple scattering is calculated NumberOfAngleVariations
11. Get Set Property NumberOfAngleVariations Integer Description Number of angle steps in the calculation of rough substrates 175 A OLE automation reference Related Properties and Methods Calc NumberOfDVariations 176 NumberOfDVariations Get Set Property NumberOfDVariations Integer Description Number of thickness steps in the calculation of rough layers Related Properties and Methods Calc NumberOfAngleVariations 175 PUModel Get Set Property PUModel Integer Description Selects the pile up model see subsection 3 6 3 Allowed values are O Accurate model 1 Fast model Straggling Get Set Property Straggling Boolean Description Specifies if energy loss and geometrical straggling are taken into account Related Properties and Methods Calc StragglingModel 177 176 A OLE automation reference ScreeningModel Get Set Property ScreeningModel Integer Description Selects the screening function to the Rutherford cross section due to partial screening of the nuclear charges by the electron shells surrounding both nuclei see section 4 4 Allowed values are O Rutherford cross section without screening Equation 4 15 1 Andersen s screening function Equation 4 17 Rutherford cross section without screening should be used only for test purposes Andersen s screening function is highly recommended and the program default StragglingModel Get Set Property StragglingModel In
12. Li AI 140 4000 7900 Nurmela 7Li Al_140 R33 Nurmela 1999 77 AM Li Li Al 170 3460 7960 27AI7LiLiAl R33 R is nen 1993 Si Li Li Si 140 4500 7800 Nurmela 7Li Si 140 R33 Nurmela 1999 Si LiLi Si 170 4450 7710 Si7LiLiSi R33 R is nen 1993 TiC Li Li Ti 140 5250 11000 Nurmela 7Li Ti 140 R33 Nurmela 1999 TiCLi Li Ti 4950 11460 Ti7LiLiTi R33 41 R is nen 1993 3 Using SIMNRA Table 3 5 Non Rutherford ERDA cross sections 0 Lab Energy keV File Reference H He H He 20 2000 3000 1HTP1X1 R33 Terwagne 1996 H He H He 30 1900 3000 1HTP1X2 R33 Terwagne 1996 H a H a 30 2500 4500 1HAP4HE30 R33 Bogdanovi Radovi 2001 H a H a 40 2500 4500 1HAP4HE40 R33 Bogdanovi Radovi 2001 H a H a 45 2500 4500 1HAP4HE45 R33 Bogdanovi Radovi 2001 H a H a 50 2500 4500 1HAP4HE50 R33 Bogdanovi Radovi 2001 H a H a 55 2500 4500 1HAP4HE55 R33 Bogdanovi Radovi 2001 H a H a 60 2500 4500 1HAP4HE60 R33 Bogdanovi Radovi 2001 H a H a 10 600 4800 HHEHHE10_KIM R33 Kim 1999 H a H a 15 600 4800 HHEHHE15_KIM R33 Kim 1999 H a H a 20 600 4800 HHEHHE20_KIM R33 Kim 1999 H a H a 25 600 4800 HHEHHE25_KIM R33 Kim 1999 H a H a 30 600 4800 HHEHHE30_KIM R33 Kim 1999 H a H a 35 600 4800 HHEHHE35_KIM R33 Kim 1999 H a H a 40 600 4800 HHEHHE40_KIM R33 Kim 1999 H a H a 10 1000 2500 ERD10H R33 Quillet 1994 H a H a 20 100
13. Sydney New York Tokyo 1989 94 J Tirira Y Serruys and P Trocellier Forward Recoil Spectrometry Plenum Press New York London 1996 94 PV Vavilov Soviet Physics J E T P 5 1957 749 94 N Bohr Mat Fys Medd Dan Vid Selsk 18 8 1948 94 95 J W Mayer and E Rimini lon Handbook for Material Analysis Academic Press New York San Francisco London 1977 94 95 96 103 M G Payne Phys Rev 185 2 1969 611 94 C Tschal r Nucl Instr Meth 61 1968 141 94 C Tschal r Nucl Instr Meth 64 1968 237 94 W K Chu Phys Rev 13 1976 2057 95 96 Q Yang D J O Connor and Z Wang Nucl Instr Meth B 61 1991 149 96 O Schmelmer G Dollinger C M Frey A Bergmaier and S Karsch Nucl Instr Meth B 145 1998 261 103 D Dieumegard D Dubreuil and G Amsel Nucl Instr Meth 166 1979 431 104 G Amsel G Battistig and A LHoir Nucl Instr Meth B 201 2003 325 107 108 A Weber H Mommsen W Sarter and A Weller Nucl Instr Meth 198 1982 527 107 A Weber and H Mommsen Nucl Instr Meth 204 1983 559 107 E Steinbauer P Bauer and J P Biersack Nucl Instr Meth B 45 1990 171 107 137 PBauer E Steinbauer and J P Biersack Nucl Instr Meth B 79 1993 443 107 137 W Eckstein and M Mayer Nucl Instr Meth B 153 1999 337 107 137 213 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 7
14. The total amount of each element is the sum of this element in all layers 3 7 2 Layer and substrate roughness In this menu the roughnesses of the current layer and of the substrate are defined Has thickness distribution Check if the current layer is rough i e if the layer thickness is not uniform but varies from point to point A rough layer is described by a distribution of layer thicknesses The distribution is divided into N steps The step number N can be adjusted by the Number of thickness steps in the Setup Calculation menu see subsection 3 6 3 FWHM of thickness distribution SIMNRA assumes a Gamma distribution of layer thick nesses see section 4 10 for details with the layer thickness as mean value The width and shape of the distribution is determined by the full width at half maximum FWHM with FWHM 2 35482 0 3 4 where is the standard deviation FWHM in 10 atoms cm Strictly speaking the Gamma distribution has only a standard deviation while the full width at half maximum FWHM is undefined However the Gamma distribution resembles a Gaussian distribution in many cases which justifies the use of the FWHM Internally SIMNRA uses only the standard deviation which is derived from the FWHM through Equation 3 4 30 3 Using SIMNRA Incident beam Target Figure 3 8 Layer structure of target and foil For the target layer 1 is at the surface the layer with the highest n
15. WOs Au alloys etc deviations from Bragg s rule disappear deviation 296 35 38 Ziegler and Manoyan 35 have developed the cores and bonds CAB model which assumes the electronic energy loss to have two contributions The effect of the cores and the effect of the bonds such as C H and C C The CAB model allows better predictions for the stopping in compounds however the bond structure has to be known Currently the CAB model or any other model which allows better predictions for the stopping in compounds is not implemented 90 4 Physics in SIMNRA However a correction factor f may be used for each ion species and each layer see section 3 7 for details If a factor f is defined for a layer then the program will use the stopping power S E with E the ion energy S E f Sprage E 4 51 Spragg E is the stopping power according to Bragg s rule Note that the factor f is energy independent 91 4 Physics 4 7 Detector energy resolution 4 7 1 Time of flight detector A time of flight TOF detector is characterized by its time resolution which determines the energy resolution The energy E is given by 1 mv 2 E 1 CIN s 2 T where m is the ion mass v the ion velocity L the free flight path and T the time of flight The energy resolution AE is determined from the time resolution AT according to 2 AT 2E 4 52 AE II Equation 4 52 is used by SIMNRA to calculate the energ
16. but SIMNRA is not able to quantify these errors It does not know how accurately you determined your energy calibration or performed the ion current measurement The error bar Aa of a fitted parameter a is determined by the shape of the y surface near the minimum A flat minimum of y allows a larger variation of a and will result in larger errors of a On a confidence level of 68 396 the usual 1c interval the error of a is obtained by varying a until y has increased by 1 12 Ax agai x axi X24 1 3 9 are is the minimised y with an optimised parameter a and the error Aa of a is Aa laa 1 aminl If we have more than one fit parameter things get more complicated 12 As an example we consider the case of two fit parameters a and a gt The Ay 1 contour now is an ellipse Figure 3 11 due to correlations between a and a and for more than two fit parameters a multi dimensional ellipsoid To find the confidence intervals for a and a we have to do the following Increase a by some amount black arrows in Figure 3 11 Now find a new minimum of y by optimising a5 a remains unchanged dotted line in Figure 3 11 Increase a and optimise a again and so on until Ay 1 For n fit parameters a a we have to increase a and optimise a a until Ay 1 As can be seen in Figure 3 11 the error bar Aa becomes nonrealistic small if only a is fitted This is a consequence of the assumption that all nonfi
17. different layers is 100 Ins Inserts a layer in front of the current layer The maximum number of different layers is 100 Del Deletes the current layer Prev Go to the previous layer Next Go to the next layer Menu bar File Read Layer Read a layer from file Attention If a layer is read from file the current layer is overwritten File Save Layer Save the current layer description to file File Read Target Read a whole target from file Attention If a target is read from file the current target is overwritten 29 3 Using SIMNRA File Save Target Save the current target to file File Write Depth Profile Save the depth profile of all elements in the target to file The file format is shown in Figure 3 9 Edit Copy Layer or pressing Ctrl C Copies the current layer to the clipboard Edit Paste Layer or pressing Ctrl V Pastes a layer from the clipboard Attention If a layer is pasted from the clipboard the current layer is overwritten Edit Copy Depth Profile Copies the depth profile of all elements in the target to the clipboard The format is identical to a depth profile file see Figure 3 9 The depth profile can be pasted into an Origin or Excel worksheet Show Target summary displays the total amounts in atoms cm of all elements in the target This is mainly useful if the target consists of plural layers composed of the same elements in different concentrations
18. scattering Plural large angle scattering cannot be treated analytically SIMNRA approximates plural scat tering effects by calculating all particle trajectories with two scattering events dual scattering see Figure 4 12 The contribution of trajectories with more than two large angle deflections is neglected Plural large angle and multiple small angle scattering may be combined in the calculations SIMNRA performs the calculation of dual scattering in the following way During each step of the incident ion particles are scattered into the whole sphere of 47 We introduce the polar system with the polar angles w p see Figure 4 13 w is the altitude and the azimuth angle After the first scattering event the scattered particles have the direction y v The scattering angle 0 of the first scattering event is given by cos 0 sina siny sin y cosa cos y 7The full Szilagyi Amsel theory is implemented in SIMNRA 5 76 and higher Earlier versions of SIMNRA treated the correlation between angular and energy spread only approximately thus resulting in somewhat different results 108 4 Physics Figure 4 13 Geometry used for the calculation of dual scattering with the altitude angle Y and azimuth angle y SIMNRA uses the Rutherford cross section for the calculation of the number of scattered particles in the first scattering event The new angle a of the particles after the first scattering is a 180
19. yw The scattering angle 05 of the second scattering event is given by cos 0 sin fj cos pg siny cos p sin f sin pg siny sin y cos p cosy 4 77 with pg the azimuth angle of the exit vector B SIMNRA subdivides the whole sphere of 47 into 10 w intervals and 12 q intervals resulting in 120 solid angle intervals SIMNRA considers only trajectories with scattering angles 64 0 gt 20 for dual scattering Trajectories with smaller scattering angles are very similar to single scattering trajectories For each solid angle interval a full backscattering spectrum with the starting depth of the particles equal to the depth of the incident ions and the new incident angle a and the new scattering angle 0 is calculated Figure 4 14 compares the simulated spectra with single and dual scattering for 500 keV He ions incident on a 100 nm gold layer on top of silicon with experimental data With the inclusion of dual scattering the experimental results are much better approximated Dual scattering gives the background between the low energy edge of Au and the Si edge and the steeper increase 8Equation 4 77 is valid in general geometry SIMNRA version 6 03 and earlier used an equation which was only valid in IBM geometry 109 4 Physics Energy keV 100 200 300 400 500 14000 Experimental Dual scattering 12000 Single scattering 10000 2 8000 E 3 Oo 6000 4000 2000 Channel Figure 4 14 500 keV 4He ions inci
20. 12CAA12C30 R33 Bogdanovi Radovi 2002 2C a a 2C 45 2000 4800 12CAA12C45 R33 Bogdanovi Radovi 2002 12C a a C 60 2100 4800 12CAA12C60 R33 Bogdanovi Radovi 2002 PC a q C 135 2100 4800 12CAA12C135 R33 Bogdanovi Radovi 2002 2C a ay C 150 2100 4800 12CAA12C150 R33 Bogdanovi Radovi 2002 BC a a 8C 165 2000 3500 AC BA65A RTR Barnes 1965 13C a a C 165 3300 6500 AC_KE68A RTR Kerr 1968 1N a 0 N 163 7 2600 4700 AN _KA58A RTR Kashy 1958 1N a a N 165 2000 6200 AN FE94A RTR Feng 1994 HN a a N 167 4550 6550 AN_FO93A RTR Foster 1993 MN a a 4N 167 7090 9070 AN FO93B RTR Foster 1993 MN a a 4N 167 8650 9000 AN_FO93C RTR Foster 1993 1N a a N 167 2 2000 4000 AN HES8A RTR Herring 1958 I N a a N 165 2 1600 2600 AN _SM61A RTR Smothich 1961 I5N a a N 165 2 2400 3800 AN_SM61B RTR Smothich 1961 I5N a a N 165 2 3800 4800 AN _SM61C RTR Smothich 1961 ISN a a N 165 2 4700 5600 AN_SM61D RTR Smothich 1961 39 3 Using SIMNRA 0 Lab Energy keV File Reference PN a a N 165 2 1600 5600 AN _SM61E RTR Smothich 1961 PN a a PN 165 2 1600 5600 AN _SMGIERTR Smothich 1961 PN a a N 165 2 3800 4800 AN MO72A RTR Mo 1972 10 a a O 158 6 6000 10500 AO HU67A RTR Hunt 1967 10 a a O 165 2050 9000 AO FE94A RTR Feng 1994 10 a a O 165 9200 9900 AO CA85A RTR Caske
21. 4 Physics 4 11 2 Calculation of pile up Due to the finite width of the electronic pulses there is always a probability of pulses to overlap This phenomenon is called pulse pile up Pile up can be minimized by decreasing the incident count rate by decreasing the incident beam current or the detector solid angle and by reducing the width of the electronic pulses Gaussian shaping with a peaking times of 0 5 us is still long enough to preserve the optimal energy resolution of most semiconductor detectors used for RBS A pile up rejector can additionally decrease the pile up level which however can never achieve a complete elimination of pile up effects SIMNRA offers two different models for calculating pile up See subsection 3 6 3 on how to select the different models and for some remarks about computing times Accurate model This model is close to physical reality Pulse shape effects and overlap of pulses according to their arrival time distribution are taken into account correctly The influence of a pile up rejector circuit is modelled realistically Major disadvantage of this model is its long computing time especially for spectra with many channels Fast model This model is less accurate than the previous one but can be calculated much faster The selection of the pile up model depends on the use of a pile up rejector circuit the pulse shaping time the desired level of accuracy and the available computer power In many c
22. Amplifier Gaussian shaping T 1 9 X ten Tsr Gaussian shaping time Digital signal processor DSP T 0 8 x Tap 0 5X Tpr er DSP filter rise time Tpr DSP filter flat top duration Table 3 1 Recommended values for the pulse rise time T Note The Pulse rise time is only available if the pile up model is set to Accurate in the Setup Calculation menu see subsection 3 6 3 Fudge time parameter Fudge time parameter for the Fast pile up model in us This parameter can be adjusted to any value matching the measured pile up in the spectrum Reasonable values are in the range 0 3 0 5 us see section 4 11 2 for more details Note The Fudge time parameter is only available if the pile up model is set to Fast in the Setup Calculation menu see subsection 3 6 3 Pile up rejector Switch to On if a pile up rejector was used during the measurement Switch to Off if the measurement was made without a pile up rejector If Canberra s CAM files are used this parameter is taken from the file But note that this is not always reliable because it cannot be excluded that the pile up rejector was enabled but had no influence due to incorrect or missing cabling Note This switch is only available if the pile up model is set to Accurate in the Setup Calculation menu This switch has no influence if the pile up model is set to Fast e Pile up rejector pair resolution time Pair resolution time of the pile up rejector in us
23. CM 1000 2000 PARCO63A RTR Cohen Ganouna 1963 Ar p p Ar 166 CM 1825 1950 PARCO63B RTR Cohen Ganouna 1963 Ar p p Ar 155 1750 2750 PARFR58A RTR Prier 1958 Ca p p Ca 160 1800 3000 PCAWI74A RTR Wilson 1974 Ti p p 1800 2150 PTIPR72A RTR Prochnow 1972 Tp Ti 160 2150 2500 PTIPR72B RTR Prochnow 1972 9 Ti p p Ti 160 2500 2800 PTIPR72C RTR Prochnow 1972 Top Ti 160 2900 3040 PTIPR72D RTR Prochnow 1972 Ti p p 1000 2600 PTIRA89A RTR Rauhala 1989 IC He He C 159 4 1800 5400 12CTTC R33 Kuan 1964 Li a a Li 112 2500 4500 ALIBO72A RTR Bohlen 1972 7Li a a Li 121 2500 4500 ALIBO72B RTR Bohlen 1972 Be a a Be 136 6000 20000 ABETA65A RTR Taylor 1965 Be a a Be 157 5 1500 6000 ABEGO73A RTR Goss 1973 Be a a Be 170 5 575 4200 ABELE94A RTR Leavitt 1994 1B a a B 170 5 975 3275 AB_MC92A RTR McIntyre 1992 NB a a B 150 8 2000 4000 AB_RA72A RTR Ramirez 1972 HB g q HB 160 5 4000 8000 AB_OT72A RTR Ott 1972 HB qg g 1B 170 5 980 3300 AB MC92B RTR McIntyre 1992 C a a C 149 4000 12000 AC_MS72A RTR Marvin 1972 C a a C 165 1810 9050 AC_FE94A RTR Feng 1994 C a a C 167 4000 7500 AC BI54A RTR Bittner 1954 C a a C 170 5000 9000 AC_CH94A RTR Cheng 1994 C a a C 170 5 1560 5000 AC_LE89A RTR Leavitt 1989 I2C q q C 30 2000 4800
24. Centre amongst others The R33 format is proposed to become a legal computational format for the Nuclear Data Network Nuclear Data Needs in Ion Beam Analysis I C Vickridge In SLong Term Needs for Nuclear Data Development Report INDC NDS 428 August 2001 International Atomic Energy Agency Vienna It is thus also necessary to provide an updated formal definition of the R33 format in order to provide the necessary specification for adoption of R33 as an accepted computational format Guiding considerations In defining the updated R33 format I have required that previous valid R33 files should also conform to the updated format This is so that R33 reading programs that conform to the updated specification will be able to read the existing R33 files providing backward compatibility There is also some redundancy in the format This is partly from intellectual laziness but also provides some checking of internal consistency to weed out errors B 2 The new R33 Format definition An R33 data file contains one cross section either as a function of laboratory incident energy or as a function of laboratory detection angle The file is made up of entries and the data section Each entry consists of a legal keyword followed by a colon followed by a space followed by data in Ascii format The keyword may be in any mixture of upper and lower case characters Legal separators for numerical data are space comma colon and semi colon characte
25. Delete all files with a length of O byte 67 3 Using SIMNRA This is a comment line This is another comment line E Stopping keV keV 1E15 at cm 1 0 5 2 0 6 4 0 7 Figure 3 13 Example of a valid stopping power data file 3 18 Using user defined stopping powers SIMNRA will use user defined stopping powers if User defined stopping powers are selected in Setup Calculation see subsection 3 6 3 To use user defined stopping powers you have to perform the following steps 1 Stopping power data files must be stored in the SIMNRA STOP directory 2 Stopping power data files are selected according to file name The file naming convention is STOP Z M Z5 DAT with Z and M the nuclear charge and mass of the ion and Z the nuclear charge of the target element M is rounded to the nearest integer value Example STOP 2 4 14 DAT should contain stopping power data for He in Si 3 The file format is shown in Figure 3 13 The files can start with an arbitrary number of comment lines These lines are ignored The stopping power data are organized in two columns as function of energy with the energy in keV and the stopping power in keV 1E15 at cm The data have to be be ordered in ascending order The data points may have irregular energy spacing i e the energy step from one data point to the next may vary The stopping power must be the total stopping power i e the sum of electronic and nuclear stopping SIMNRA uses li
26. E of the heavy product created in the nuclear reaction is given in the laboratory system by Asa 1 272 E ErAja cos t E sin d 4 9 Aza is the emission angle of the heavy product in the laboratory system For A14 lt Aas only the plus sign in Equation 4 9 applies If A 4 gt A53 then Equation 4 9 has two solutions and the 75 4 Physics maximum possible emission angle of the heavy product is A53 y 12 Zu arcsin E 4 10 Aza SIMNRA uses Equation 4 7 and Equation 4 9 only with the plus sign The second solution is neglected 76 4 Physics 4 3 Number of backscattered particles The number of backscattered particles Q De the area of the brick in Figure 4 1 from a thin layer with thickness Ax can be calculated by using the cross section at the mean energy E in the layer NAQ Q o E Ax 4 11 cosa with N AQ the number of incident particles times the solid angle of the detector o E the differ ential cross section evaluated at the mean energy E and a the angle of incidence SIMNRA 5 01 and earlier used Equation 4 11 for the calculation of the number of backscattered particles This is however only valid if the layer is sufficiently thin i e if the energy loss in the layer is small enough so that the cross section does not change strongly If the cross section has structures such as sharp resonances this usually requires very thin layers which cannot be guaranteed if Automatic ste
27. Garching Germany Massimo Chiari OUNEN Sezione di Firenze Italy Ana Rita Lopes Ramos Nuclear and Technological Institute Sacav m Portugal Alexander Gurbich Institute of Physics and Power Engineering Obninsk Russia and Jari Likonen VTT Espoo Finland SIMNRA was developed at the Max Planck Institut f r Plasmaphysik Garching Germany The R33 file format and the R33Manager were developed by Ian Vickridge Universit Paris France The text of Appendix was written by I Vickridge and has been taken from the file R33Help htm Starting from version 5 84 SIMNRA uses Inno Setup for creating the setup program 143 6 Acknowledgements SIMNRA uses libxml2 for reading and writing xml files 144 A OLE automation reference his section describes OLE 2 0 automation support in SIMNRA SIMNRA is an OLE automa T tion server which allows other applications to control SIMNRA This is useful for batch processing of a large number of spectra and the like A short overview of the OLE objects and methods is given below for a complete description of the parameters associated with OLE automation methods see Appendix A Some sample programs can be found in section A 10 Objects SIMNRA exports the following OLE automation objects Simnra App The application itself Simnra Setup Experimental setup Simnra Calc Parameters for calculation Simnra Target Target with layers and elements Simnra Fit Fit
28. NP S P Y Pii Pini N S 9P P Pigs 4 94 j 1 i a i 1 j p with the channel content of the undistorted spectrum without pile up ng The total number of counts lost due to pile up L 2523 L and the total number of gained pulses G KS G are connected through L 2G i e the total number of lost pulses is twice the number of gains Effect of a pile up rejector A pile up rejector PUR rejects pulse pairs if their time lag t is larger than the pile up rejector pair resolution time 7 Pulses arriving almost simultaneously i e with a time lag smaller than 75 are not rejected A pile up rejector therefore can only reduce the amount of pile up but is unable to eliminate it completely The PUR pair resolution time can be found in the technical specifications of the spectroscopy amplifier and is usually lt 0 5 us with typical values of 0 3 0 5 us A pile up rejector is modelled in the following way If the pile up rejector is on then pile up occurs only if the time lag t between the two pulses is smaller than Ty i e P _ ae Iw t t if ty t2 T2 ijk 0 otherwise see Equation 4 88 The effect of a pile up rejector on pile up from a single peak is shown in Figure 4 30 Pulse pairs arriving almost simultaneously are not influenced by the pile up rejector resulting in a pile up peak at twice the channel number than the original peak Pile up of pulses with a time lag larger than the pair resolution time which gi
29. R CUnknown String Note A concise bibliographic source preferable or another indication of where the data has come from avoid if possible This field should contain the most authoritative original source for the data This will usually be the original publi cation or thesis reference In some cases data has been input by experimenters before or without publication In this case this entry should contain something like Measured and input by D Withrington It should be kept small an upper limit of 256 characters is suggested but not required It would be expected that further details pertaining to Mrs Withrington would be found in the Comment R Cunknown lt String gt Note The name of person or institution responsible for creating the R33 file For R33 files automatically created from Exfor files this would be IAEA or NNDC or International Nuclear Data Network or whatever No provision is made here for including update histories however this may be accommodated in the Comment field 0 String 0 String Note The address of the person or institution responsible for creating the R33 file Up to nine lines of address information may be included This can include telephone numbers emails and so on R 0 n Note The serial number will be a number providing a unique link back to the Exfor dataset from which the R33 file was generated The default value of zero means that this number has not b
30. Related Properties and Methods BottomAxisMin 193 BottomAxisMin Get Set Property BottomAxisMin Double Description Bottom axis minimum Related Properties and Methods BottomAxisMax 193 193 A OLE automation reference LeftAxisMax Get Set Property LeftAxisMax Double Description Left axis maximum Related Properties and Methods LeftAxisMin 194 LeftAxisMin Get Set Property LeftAxisMin Double Description Left axis minimum Related Properties and Methods LeftAxisMax 194 NumberOfChannels Get Property NumberOfChannels spID Integer Integer Description Number of channels in the experimental or simulated spectrum NumberOfChan nels is readonly Related Properties and Methods spID 192 194 A OLE automation reference A 7 3 Methods Data Function Data spID chan Integer Double Description Value of experimental or simulated data in channel chan Parameters spID Selects the experimental or simulated spectrum chan Channel number with 0 lt chan lt NumberOfChannels Return Value Returns the value in channel chan Related Properties and Methods spID 192 Integrate Function Integrate spID lowChannel upChannel Integer Double Description Sum of counts of the experimental or simulated spectrum in the range from lowChannel to upChannel Parameters spID Selects the experimental or simulated spectrum lowChannel Lower channel with 0 lt lowChannel NumberO
31. T T Other approximations including the true pulse shape by numerical integration can be found in 83 Pile up results in losses and gains of pulses in each channel k Losses in channel k are due to pile up with pulses j into channel i where the pulses k may pile up with a following pulse j or may pile up with a preceding pulse j The losses from channel k are given by m j k Lk NP XP Y Pu Piri 4 91 j 1 i a 130 4 Physics True signal 15r Parabola 2 o S tol i a E w 05r E D o 0 0 3 2 1 0 1 2 3 4 Time us Figure 4 28 Comparison of a real pulse Ortec 672 spectroscopy amplifier Gaussian shaping shaping time 1 us with the parabolic pulse approximation pulse rise time T 1 9 us according to Table 3 1 1 0 True signal 7 Parabola Signal amplitude V al 0 0 2 1 0 1 2 Time us Figure 4 29 Comparison of a trapezoidal pulse shape as used by digital signal processors DSP filter rise time 1 us DSP flat top duration 0 2 us with the parabolic pulse approximation pulse rise time T 0 9 us according to Table 3 1 131 4 Physics where a is the largest of k and j The gain in channel k is due to pile up of pulses i and j k 1k 1 i 1 j p where p k i The content of each channel of the spectrum with pile up hc U is then given by nl m Lt 4 93 m jtk k 1k 1 x ny
32. Using SIMNRA by SIMNRA The cross section units have to be mbarn sr for differential cross sections and mbarn for total cross sections SIMNRA expects the data to be arranged in order of ascending energy e Scale conversion factors EnFactors and SigFactors may be used with SIMNRA 5 02 and higher Scale conversion factors must not be used with earlier versions of SIMNRA because they are ignored and will result in incorrect cross section values Refer to Appendix B how to use scale conversion factors But note that the use of scale conversion factors is not recommended 8This is only a problem with some files in the IBANDL data library at http www nds iaea org ibandl These files should not be used with SIMNRA 5 01 and earlier They can be used with SIMNRA 5 02 and higher 65 3 Using SIMNRA 3 17 Using SRIM stopping powers SRIM is a program for the calculation of stopping powers and ion ranges SRIM is not part of SIMNRA but is developed by J Ziegler and can be downloaded from www srim org SIMNRA uses SRIM for calculating stopping power tables which are then used for simulations SIMNRA requires SRIM 2003 or later and has been tested with SRIM 2003 to SRIM 2010 In order to use SRIM stopping powers you must perform the following steps 1 Download and install SRIM on your computer 2 Run SIMNRA Click Options Preferences and go to the Directories tab Enter the path to the SRIM program directory i e the
33. a slightly thicker W layer 3 6 um for best fit The dashed line is calculated for a rough W layer characterized by a Gamma distribution of layer thicknesses with a mean thickness of 3 5 um and standard deviation o 0 3 um on a rough carbon substrate characterized by a Lorentz distribution of tilt angles with FWHM 20 The roughnesses of the layer and the substrate are assumed to be independent and plural scattering is not taken into account The W peak channels gt 650 is already well described but the low energy tail below the peak is underestimated The solid line uses the same roughness parameters but takes additionally plural scattering into account Now the whole experimental spectrum is reproduced well Compared to the smooth layer the contribution of plural scattering has increased strongly which is due to an enhancement of plural scattering at inclined incidence The height and shape of the low energy tail below the W peak in channels 650 are determined by the wings of the tilt angle distribution with inclination angles gt 45 The observed tilt angle distribution see 120 4 Physics E 200 E s 0 8 200 o gt 0 500 1000 1500 201 X position um Experimental Gauss x cos 400 Lorentz x cos o a 300 jum o D K 200 E gt 00 60 40 20 0 20 40 60 Tilt angle 9 Figure 4 22 Top Line profile of a carbon fibre composite CFC surface Bottom Histogram of the local tilt angle distr
34. about this file format 2 The RTR Ratio To Rutherford file format These files contain non Rutherford cross sections for backscattering of protons and a particles The files contain the ratio of measured to Rutherford cross sections The majority of the data has been digitised from the original publications by R P Cox J A Leavitt and L C McIntyre Jr from Arizona University These cross section data have been published in 9 All files with this extension have been taken from SigmaBase The references of the original publications are found in 9 SIMNRA distinguishes between three different types of scattering events for each isotope 1 Backscattering of projectiles 2 Creation of recoils 3 Nuclear reactions The chosen cross sections for each type of scattering event must be unambiguous You can choose for example Rutherford cross section for backscattering in the energy range from 34 3 Using SIMNRA 0 000 0 999 Mey some non Rutherford cross section for backscattering in the energy range from 1 000 1 999 MeV and a different cross section for backscattering in the energy range from 2 000 3 000 MeV You cannot choose however Rutherford cross section for backscattering in the range 0 000 2 000 MeV and another cross section for backscattering in the energy range from 1 000 2 000 MeV In this case the program does not know which cross section it should use in the range from 1 000 2 000 MeV and you will get the error message Ene
35. atom proportions or the value natural case insensitive which means that a target of naturally occurring isotopic composition has been used Isotopes are specified as for the reaction string without shorthand notation Example Target 12C 23 0 13C 26 0 If the proportions do not sum to 100 then it is assumed that they are relative amounts In the example given 23 49 of the atoms are 12C and 26 49 are 13C If the Composition entry exists and has a legal value then the values in the masses entry should correspond to the appropriate weighted sum indicated in the composition keyword For example if the target for an elastic cross section is natural silicon then the mass given should be 28 086 the weighted sum of stable Si isotopes in natural abundance R 0 0 lt r 5 r r r gt Note A list of up to five Q values expressed in keV separated by legal separators As explained in the Reaction entry some cross sections are for multiple particle groups for example when the groups are not resolved experimentally In this case a Q value is required for each particle contributing to the cross section R CEnergy lt String gt Note Allowed values are Energy and Angle This entry says whether the data contained in this file are for a cross section as a function of laboratory energy Energy or laboratory angle Angle M1 R 0 0 lt r gt M1 R 1 0 lt r gt Note Theta gives the laborat
36. atomic concentration or as areal density If Concentration is 28 3 Using SIMNRA selected the total layer thickness and the concentrations of all elements are entered If Areal density is selected the areal density of each element is entered the total layer thickness is calculated as the sum of all elemental areal densities Correction factor s for stopping power SIMNRA uses Bragg s rule to calculate the stopping power of a layer see subsection 4 6 5 for more details However it has been shown experimentally that for several compounds like hydrocarbons or oxides deviations from Bragg s rule occur To account for deviations from Braggg s rule a correction factor f can be used and the program will use the stopping power S E as function of energy E S E f SBragg E 3 3 Spragg E is the stopping power according to Bragg s rule Note that the factor f is energy independent An individual factor f for each ion species and each layer may be defined If no factor f is given the program uses f 1 i e uses Bragg s rule Layer and substrate roughness Click the button if the current layer or the substrate is rough See subsection 3 7 2 for details Manipulation of layers To manipulate layers use the buttons in the Layer manipulation box Additionally layers can be copied to and pasted from the clipboard and layers can be saved to and read from file Add Adds a layer The added layer will be the last layer The maximum number of
37. be given Integer in the second column the number of counts must be given Double The two columns are separated by an arbitrary number of blanks or tabs Each line must end with CR LF The data file may contain up to 8192 channels An example for a valid data file is given in Figure 3 2 Read Spectrum Data Canberra Allows the import of spectral data stored in Canberra s CAM file format SIMNRA uses Canberra s Genie 2000 software package for reading CAM files The Genie 2000 package is not part of SIMNRA and must be obtained separately from Canberra Industries This package must be installed correctly before you can read CAM files The dynamic link libraries sad dll etc must be in the search path and the virtual data manager VDM must be installed SIMNRA has been tested with Genie 2000 versions 1 3 and 1 4 Note SIMNRA reads only spectral data stored in CAM files Any other information which may be stored in the CAM file like energy calibration etc is ignored Read Spectrum Data IPP Reads experimental data stored in the data file format used at the IPP Garching Germany until 1999 This data file format will not be described here Read Spectrum Data ISI Reads experimental data stored in the data file format used at ISI J lich Germany This data file format will not be described here Read Spectrum Data MCERD Reads a spectrum calculated by the Monte Carlo code MCERD written by K Arstila The data are
38. cross section 80 R33 file format 34 62 204 RTR file format 34 Rutherford cross section 78 79 high energy deviation 80 recoil cross section 79 scattering cross section 78 SCr ening isi eege e EE 23 78 D Data exchange ce eee eee eee eee 58 Excel 291 saad Eder il 58 Origin biomas er bee hehe teens 58 RUMP aunar SE UE Rp Re 58 WINDE e dee RA a tes 60 Dead layer unan rinda see Detector Dead time 42 eere cr eet Pret ve 126 Density conversion essss 48 Depth profile 30 Detector dead layer 2 s eoe bee e Rees 69 electrostatic detector 15 92 Delta E E ccc cece cece eens 15 energy resolution 92 energy calibration 12 69 detector nonlinearity 12 69 different ion species 12 69 non linear 12 69 quadratic suss 12 69 energy resolution 13 92 different ion species 13 free flight path 15 92 plasma effect ooooooococmomomo 69 pulse height defect 69 resolution see Detector energy resolution see Detector time resolution semiconductor detector 69 solid angle 13 solid state detector 13 15 69 e eene Dx tee erasers 15 thickness 25 vere IER ex RS 15 time resolution 15 92 time of flight
39. error handling Related Properties and Methods App ShowMessages 154 153 A OLE automation reference Left Get Set Property Left Integer Description Position of the left side of the form relative to the screen in pixels Related Properties and Methods App Height 153 App Top 155 App Width 155 ShowMessages Get Set Property ShowMessages Boolean Default Value false Description Specifies if error messages are shown or suppressed If ShowMessages is true program execution is stopped if an error is encountered and a message box with an error description or warning is shown Program execution is resumed after pressing the OK button If ShowMessages is false the message box is suppressed and program execution continues The routine which produced the error like App Open or App CalculateSpectrum returns an error flag The text of the error message can be retrieved with LastMessage See section A 9 for more details about error handling Related Properties and Methods App LastMessage 153 SpectrumChanged 154 A OLE automation reference Get Set Property SpectrumChanged Boolean Description Indicated if the calculated spectrum has changed due to a new calculation SIM NRA will set SpectrumChanged to true if a new spectrum has been calculated But note that SIMNRA will never set SpectrumChanged to false this has to be done by the OLE client SpectrumChanged can be used to inform OLE clients
40. in the format Energy Counts with energy in MeV The energy calibration is taken from the file Read Spectrum Data User Allows to read experimental data stored in any user defined format A dynamic link library dll has to be supplied by the user which reads the data and passes them to SIMNRA See section 3 15 for more details Write Spectrum Data This menu item exports the experimental and simulated data as columns into an ASCII file You can import this file easily into any plot program such as Excel Origin or Mathematica 2 lt CR gt means Carriage Return 13 decimal lt LF gt means Line Feed 10 decimal 3 Using SIMNRA The file format is as follows The first line is a comment line which contains information about the contents of the different columns The first column is the channel number the second column contains the experimental data This column is set to zero if experimental data are not available the third column contains the simulated data This column is set to zero if simulated data are not available If the Element spectra option in Setup Calculation is checked then the next columns will contain the simulated spectra for each element in the target The columns are separated with blanks The columns are separated by tabs RUMP Read RBS File This menu item allows to read a binary RBS file produced by RUMP containing experimental parameters Type of incident particles incident energy scat
41. integer starting channel is used 3 14 3 IBA data furnace The IBA data furnace NDE WiNDF was developed at the University of Surrey and is available from www ee surrey ac uk Research SCRIBA ndf This program converts energy spectra to depth profiles The depth profiles are stored in RUMP s sample descrition format LCM You can read these files with the command File Read RUMP see section 3 14 2 60 3 Using SIMNRA 3 15 Importing spectrum data in any format SIMNRA can read experimental spectrum data in several formats including ASCII see section 3 4 But many laboratories have their own spectrum data file formats SIMNRA offers the possibility to import any type of experimental data by supplying a dynamic link library DLL which reads the data and passes them to SIMNRA This DLL must be supplied by the user and is called if File Read Spectrum Data User is clicked This section describes the details of this DLL The DLL name must be user dll It must be located in the SIMNRA UserDil subdirectory otherwise SIMNRA will not find it The DLL must export a function ReadData exact spelling defined as follows Function ReadData FileName PChar Var Count Integer Data Pointer Integer stdcall Filename Input parameter Null terminated string with the full name including path to the file which shall be read Count Output parameter Pointer to a 32 bit signed integer value which indicates how many channels were actuall
42. is printed the comment field is printed on successive lines that are not longer than 80 characters The double CR LF sequence that signals the end of the comment is simply a blank line It is not felt necessary to specify an upper limit to the size of the comment however it is expected that a useful comment would not be longer than a few tens of lines or a few thousand characters Note that Unix systems place only a LF character to signal an end of line This is illegal for R33 files There are freeware and shareware utilities that can add the necessary CR characters if R33 files are generated under Unix Version O CR33 String 206 Source Name Address1 Address9 Serial Number Reaction B The R33 cross section file format Note Allowed values are case insensitive R33 and R33a This entry can be used to signal that the file conforms to the special subset of R33 files proposed by M O Thompson for elastic scattering cross sections for use in RUMP Sigmabase files will always be DSIR R33 but the R33a variant is detailed here for com pleteness All R33a files are legal R33 files but R33a files have the following additional conditions 1 The Version entry is required and must be the first entry after the Comment 2 Only elastic cross sections can be in valid R33a files 3 Nvalues must either not be present so that Data and EndData entries are used or have a value of less than or equal to zero
43. is shown in Figure 4 3 The Rutherford cross section is a linear superposition of the Rutherford scattering and recoil cross sections from Equation 4 15 and Equation 4 18 The experimental data deviate significantly from the Rutherford prediction and have to be described by the Mott cross section This case may occur in heavy ion ERDA if the incident ion is present as element in the sample Warning Mott scattering is currently not implemented in SIMNRA The use of Rutherford scattering and recoil cross sections for identical particles in forward direction 0 lt 0 lt 90 may result in incorrect cross section data If you apply scattering of identical particles do not use Rutherford scattering and recoil cross sections in the Reactions menu section 3 8 Define a reaction cross section according to the Mott scattering formula 80 4 Physics e ELASTIC SCATTERING 12 12 C A CENTER OE MASS DIFFERENTIAL CROSS SECTION mb ster o 20 40 60 80 100 120 CENTER OF MASS SCATTERING ANGLE Figure 4 3 Angular distribution for elastic scattering of C on C at a center of mass energy of 5 MeV The solid curve is the Rutherford prediction the dashed curve is the Mott prediction Dots are experimental data From 29 81 4 Physics 4 5 Evaluation of energy loss The energy E of a particle after passing through a layer of material with thickness x is give
44. keV FWHM Related Properties and Methods Setup Energy 167 Beta Get Set Property Beta Double Description Exit angle p deg Related Properties and Methods Setup Alpha 164 Setup Theta 170 Setup SetBeta 171 CalibrationLinear Get Set Property CalibrationLinear Double Description Linear calibration term B for energy calibration see Equation 3 1 keV channel 165 A OLE automation reference Related Properties and Methods Setup CalibrationOffset 166 Setup CalibrationQuadratic 166 CalibrationOffset Get Set Property CalibrationOffset Double Description Calibration offset A for energy calibration see Equation 3 1 keV Related Properties and Methods Setup CalibrationLinear 165 Setup CalibrationQuadratic 166 CalibrationQuadratic Get Set Property CalibrationQuadratic Double Description Quadratic calibration term C for energy calibration see Equation 3 1 keV channel Related Properties and Methods Setup CalibrationLinear 165 Setup CalibrationOffset 166 DetectorResolution Get Set Property DetectorResolution Double Description Detector resolution keV FWHM 166 A OLE automation reference DetectorType Get Set Property DetectorType Integer Description Type of detector Allowed values are O Solid state detector 1 Time of flight detector 2 Electrostatic detector Related Properties and Methods Setup DetectorResolution 166
45. section Straggling Specifies if energy loss and geometrical straggling are taken into account StragglingModel Selects the electronic energy loss straggling model SubstrateRoughnessDimension Dimensionality of substrate roughness ZBStopping Selects Ziegler Biersack or Andersen Ziegler stopping 148 A OLE automation reference Simnra Target AddElement Adds an element to a layer AddLayer Adds a layer to the target DeleteElement Deletes an element from a layer DeleteLayer Deletes a layer from the target ElementConcentration Concentration of an element in a layer ElementName Name of an element in a layer HasLayerRoughness Specifies if a layer is rough HasSubstrateRoughness Specifies if the substrate is rough InsertLayer Inserts a layer LayerRoughness FWHM of the roughness of a layer 10 atoms cm LayerThickness Thickness of a layer 10 atoms cm NumberOfElements Number of different elements in a layer NumberOfLayers Total number of layers in the target ReadTarget Read a target description from file SaveTargetAs Save a target description to file SubstrateRoughness FWHM of the substrate roughness deg SubstrateRoughnessDistribution Distribution function of the substrate roughness Simnra Fit Accuracy Desired accuracy of the fit Chi2 Quadratic deviation y between the simulated and measured data points Chi2Evalua
46. that the calculated spectrum has changed The client should set SpectrumChanged to false after having obtained the spectrum Related Properties and Methods App CalculatingSpectrum 151 Top Get Set Property Top Integer Description Position of the top of the form relative to the screen in pixels Related Properties and Methods App Height 153 App Left 154 App Width 155 Width Get Set Property Width Integer Description Width of the main form in pixels Related Properties and Methods 155 A OLE automation reference App Height 153 App Left 154 App Top 155 A 2 2 Methods BringToFront Procedure BringToFront Description Brings SIMNRA to the front above all other applications Parameters None Return Value None Related Properties and Methods App Active 151 App Minimize 160 App Restore 162 CalculateSpectrum Function CalculateSpectrum Boolean Description Calculates a simulated spectrum See section 3 9 for details and differences to App CalculateSpectrumFast Parameters None 156 A OLE automation reference Return Value Returns true if the calculation succeeded Related Properties and Methods App CalculateSpectrumToDepth 157 App CalculateSpectrumFast 157 App DeleteSpectrumOnCalculate 152 CalculateSpectrumFast Function CalculateSpectrumFast Boolean Description Calculates a fast simulated spectrum See section 3 9 for details and differences t
47. wade hae ae ed ae a ae ee hae ao wo 151 e EENG Aerer ts edt wld ETT 151 22 9 Ee EE Bia eae ea e Lean eet SU 156 tee SSP aea Tue ddp de da bbe eae Sew ee 164 Adol Properties s ux Waa ANEN oe p ee EN ae e RR Pe ur 164 Ade METaddS ri rs a e a e e 171 AE EE 172 2 7 EEN A eg Boge ere Ae episcop ah GAY Eg er ee 172 ii AA 178 A Tec Propere e crure E A AA A he qr qr 178 Avo De MENOS e 2 4 coe depen ek pode aL pie idee D Dei 183 Contents EE A RNA 186 NN Properes x o acs 4 woe a aM eA iae A a EEN E 187 E A Ee due Eug Enger ee Eu Eats 192 Arte SMCA SPEC A e ee EE EE eur debo 192 Adol Input parameter ese gh E wi e wh ey a AE 192 A 7 2 PrOpettieS o iun E eom a ANER Dae AE AER ac 193 e ii id 195 PB 5minra StOpDIME x resista dodo da oda ds 196 ACS Ay IMPUNE parameter iba de da doe Se tee eed eb oe Pe ead 196 ABD Methods e ayare bin ke e OE SEE EAD EEE EE SEER GEE ES 196 AO Eror handing EEN 200 ATO Programme EEN 201 B The R33 cross section file format 204 RBE Introduction socorro 204 B 2 The new R33 Format definition o oo e 205 BI Syntax of an RSS ENUY A EN e a ET a we er SN OE 206 ES Litol legal ERES sui a ER e er EE 206 Bibliography 211 Index 216 vi Registration and payment information SIMNRA is not free It is a shareware program see below for pricing details You can use SIMNRA for a trial period of thirty 30 days without fee If you want to use SIMNRA after this period
48. with other programs ida o Rey pep ig Oe as 58 3 14 1 Graphics programs Excel Origin e 58 DIS Z RUMP 42 aa hee eq qoe OE SEER qu EP debes 58 314 3 BA dia MARS tas ra ia oe 60 2 15 Importing spectrum data Im any format a 61 3 16 Adding NeW crass s ctiondata sopp aoe aes ERA Renee nU ER epos 62 3 16 1 The RSS Mile AAA 62 3 17 Using SRIM Stopping DOWEfS 22 2 40 i E EE Be oh Rae e m 66 3 17 1 Trouble EE 66 3 18 Using user defined stopping powers so e se et ess EN RR SEN a 68 3 19 Bnerpy CalibratiDH issues 2 E e E AR Ae RS ES 69 3 19 1 Detector nonlinearity d eraa ox Re Ea IURE mos Rex NUR a de Rs 69 3 19 2 Energy calibration for different ion Species o o oooooo 69 3 20 Programming EMELIE E EE ee 70 3 20 1 Gommand line parameters sase ep arre e SERES 70 2 20 2 OLE QULOTHAEIODE Y d dh a E RERO EE ta 70 Physics 71 Z1 Atomic data cua etes di a eu e aub 73 4 2 Scattering kinematics set AA E Ee gab sa ed 74 22 1 Elastic scattering ca ocu decked Si aan e dc So Sep a 74 122 AE ge EE 74 43 Numberof backscattered particles dass da a 77 474 ERENNERT E E ha 78 4 4 1 Rutherford cross sections Lou 5 00h bho ens ad 78 4 4 2 Non Rutherford cross sections 80 45 Evaluation of energy loss ia A E Y BOR NC 82 4 6 Stoppi g poWerdata 2 426 eri A UR a A A 85 SEET Anders n Ziegler stopping a a Pee A 85 46 2 Ziegler Biersack StOppin EENHEETEN 87 AG 3e ET 250294 9 uoc Sere
49. you have to pay the registration fee and you have to register the program The pricing is as follows 250 1 license 450 2licenses 600 3 licenses 700 4 licenses 800 5 licenses on request site license Registered users of any previous version of SIMNRA can upgrade their registration for a reduced fee 100 per license for registered users of any previous version of SIMNRA Each license is valid for one computer Installation of SIMNRA on several computers requires several licenses A site license which allows installation on all computers of a specific site is available on request To register the program and get a registration number either send an email a letter by surface mail or a fax to Dr Matej Mayer The address can be found on the title page of this manual You will receive your registration number and an invoice with full payment details within a few days Run the program and click Help Register to enter the registration number Most cross section data files included with SIMNRA have been taken from SigmaBase These cross section data files are not included in the shareware fee but are freely available from SigmaBase See the file ibaserver physics isu edu sigmabase newuser html for more informa tion about SigmaBase The stopping power data files SCOEE95A and SCOER95B have been vii Contents taken from the SRIM 97 distribution These files are not included in the shareware fee but are freely avai
50. 0 NRA file format 1 IBA data format IDF file 2 XNRA file format See section 3 4 for more details about the file formats FileType is optional and can be omitted If FileType is omitted then a file in NRA file format is written Returns true if the file was saved successfully Related Properties and Methods App Open 161 Show Procedure Show Description Shows SIMNRA if it was hidden Parameters None Return Value None Related Properties and Methods 163 A OLE automation reference App Hide 159 WriteSpectrumData Function WriteSpectrumData FileName WideString Boolean Description Writes all spectra experimental simulated in ASCII format to a file See File Write Spectrum Data in section 3 4 for a description of the file format Parameters FileName The name of the data file including path If the file already exists it will be overwritten Return Value Returns true if the file was written successfully Related Properties and Methods App ReadSpectrumData 161 App CopySpectrumData 158 A 3 Simnra Setup The Simnra Setup object represents the experimental setup A 3 1 Properties Alpha Get Set Property Alpha Double Description Incident angle o deg 164 A OLE automation reference Related Properties and Methods Setup Beta 165 Setup Theta 170 Beamspread Get Set Property Beamspread Double Description Energy spread of incident beam
51. 0 0 785 0 0 0 4 55E 0000 0 0 EndData Figure 3 12 Example for a cross section data file in the R33 file format 63 3 Using SIMNRA A line containing the string Masses SIMNRA will read the masses of the particles from this line All masses in amu The first mass is the mass of the incident particle the second mass is the mass of the target particle the third mass is the mass of the outgoing particle for which the cross section is valid and the fourth mass is the mass of the other reaction product The masses may be rounded to the nearest integer value SIMNRA will replace the given masses by the exact values Warning Note that the masses are given in a different order than in the Reaction string For the reaction 160 d a0 14N the correct line is Masses 2 16 4 14 This is a permanent source of error so check your input carefully In some cases for example if the file contains elastic scattering data the cross section values are not for a specific isotope but for natural isotopic composition In this case the mean target mass should be used If the cross section values are for natural isotopic target composition rather than for a specific isotope a line containing the string Composition Natural has to be present In this case the given cross section is used for all isotopes This line has to be omitted if the cross section is for a specific isotope Other compositions than Natural must not be used Al
52. 0 2500 ERD20H R33 Quillet 1994 H a H a 30 1000 2500 ERD30H R33 Quillet 1994 H a H a 20 1000 3000 HHEHHE20 R33 Baglin 1992 H a H a 25 1000 3000 HHEHHE25 R33 Baglin 1992 H a H a 30 1000 3000 HHEHHE30 R33 Baglin 1992 H a H a 35 1000 3000 HHEHHE35 R33 Baglin 1992 D a D a 10 1000 2500 ERD10D R33 Quillet 1994 D a D a 20 1000 2500 ERD20D R33 Quillet 1994 D a D a 30 1000 2500 ERD30D R33 Quillet 1994 D a D a 20 1000 3000 DHEDHE20 R33 Kellock 1993 D a D a 25 1000 3000 DHEDHE25 R33 Kellock 1993 D a D a 30 1000 3000 DHEDHE30 R33 Kellock 1993 D a D a 35 1000 3000 DHEDHE35 R33 Kellock 1993 D a D a 40 1000 3000 DHEDHE40 R33 Kellock 1993 T a T a 30 500 2700 THETHE30 R33 Sawicki 1988 42 3 Using SIMNRA Table 3 6 Nuclear reactions cross sections Total means that the data file contains total cross section data Files without energy range contain only Q values but no cross section data These files can be used only for kinematic calculations but not for simulations 0 Lab Energy keV File Reference D dp T Total 5 5000 2DDPR33 Bosch 1992 D d t p Total 5 5000 2DDT R33 Bosch 1992 D d He n Total 1 5000 2DD3HE R33 Bosch 1992 D t He n Total 1 1370 2DTA 3 R33 Bosch 1992 D He a p Total 100 2500 2DTA_1 R33 M ller 1980 DCHea p Total 10 2240 2DTA 2 R33 Bosch 1992 DCHe p a Total 210 2150 2DTP_1 R33 M ller 1980 D He pio Total 280 24
53. 0 CHIARLR33 Chiari 2001 B p p B 625 3300 H11B115 CHIARLR33 Chiari 2001 HB p p B 650 3300 H11B120 CHIARLR33 Chiari 2001 B pp B 600 3300 H11B125 CHIARLR33 Chiari 2001 B pp B 500 3300 H11B130 CHIARLR33 Chiari 2001 B pp B 500 3300 H11B135 CHIARLR33 Chiari 2001 HB p p B 500 3300 H11B140 CHIARLR33 Chiari 2001 HB p p B 500 3300 H11B145 CHIARLR33 Chiari 2001 B pp B 500 3300 H11B150_CHIARI R33 Chiari 2001 B pp B 500 2000 PB TA56A RTR Trautfest 1956 B pp B 500 3300 H11B155_CHIARI R33 Chiari 2001 HB p p B 2200 3300 11BPPB_1 R33 Symons 1963 36 3 Using SIMNRA 0 Lab Energy keV File Reference HB p p B 160 500 3300 H11B160 CHIARLR33 Chiari 2001 B pp B 1614 1100 3800 11BPPB R33 Segel 1965 B p p B 165 500 3300 H11B165 CHIARLR33 Chiari 2001 B pp B 165 1700 2700 11BPPB_2 Mayer 1998 HB p p B 170 500 3300 H11B170_CHIARI R33 Chiari 2001 C p p C 100 340 3000 HC100 MAZZONLR33 Mazzoni 1998 C p p C 105 340 3000 HC105 MAZZONLR33 Mazzoni 1998 C p p c 110 340 3000 HC110 MAZZONLR33 Mazzoni 1998 C ppc 115 340 3000 HC115 MAZZONLR33 Mazzoni 1998 C p p C 120 340 3000 HC120 MAZZONLR33 Mazzoni 1998 C p p C 125 340 3000 HC125 MAZZONLR33 Mazzoni 1998 C p p c 130 340 3000 HC130 MAZZONLR33 Mazzoni 1998 C p p C 135
54. 0 PN LA67B RTR Lambert 1967 4N p p N 167 2 3600 4100 PN_OL58A RTR Olness 1958 N p p iN 170 1450 2300 PN_RA85A RTR Rauhala 1985 N p p N 170 2700 3100 HN170 GUOHUA R33 Guohua 1991 37 3 Using SIMNRA 0 Lab Energy keV File Reference 4N p p 4N 178 500 2500 HN178_RAMOS R33 Ramos 2002 160 p p 60 149 5 2450 2850 PO GO65A RTR Gomes 1965 160 p p 60 165 100 4080 HO165_GURBICH R33 Gurbich 1997 160 p p O 170 1000 3580 PO_AM93A RTR Amirikas 1993 O p p O 170 700 4000 160PPO R33 Gurbich 1997 160 p p 0 178 750 2500 HO178 RAMOS R33 Ramos 2002 PF p p F 150 2000 5000 PF_BO93A RTR Bogdanovic 1993 I F p p F 160 500 1300 PF DE56A RTR Dearnaly 1956 PF p p F 160 1300 2064 PF DE56B RTR Dearnaly 1956 PE p p F 160 500 1300 PF_DE56C RTR Dearnaly 1956 MR p p F 160 1300 1550 PF_DE56D RTR Dearnaly 1956 19F p p F 165 850 1010 PF_KN89A RTR Knox 1989 I F p p F 165 1000 1875 PF KN89B RTR Knox 1989 19F p p F 165 1350 1550 PF KN89C RTR Knox 1989 PE p p F 158 7 600 1800 PF_WE55A RTR Webb 1955 F p p F 158 7 1300 1500 PF_WE55B RTR Webb 1955 Ne p p Ne 166 CM 1500 2800 PNELA71A RTR Lambert 1971 23Na p p Na 156 5 550 1450 PNABA56A RTR Bauman 1956 Mg p p Mg 164 400 4000 PMGMO51A RTR Mooring 1951 Mg p p Mg 164 792 856 PMGMO51E RTR Mooring 1951 Mpg p p Mg 164 1466 1501 PMGM
55. 00 2DTP_2 R33 Bonner 1952 D Hep a Total 100 2500 2DTP 3 R33 M ller 1980 D He p a Total 10 2240 2DTP 4 R33 Bosch 1992 D He p a 135 10 6000 2DTP 5 R33 Alimov 2005 T d He n Total 1 910 3TDA R33 Bosch 1992 10 1500 3HEDA 1 R33 Bosch 1992 He D p a Total 190 1600 3HEDP 1 R33 Bonner 1952 He dp a Total 10 1500 3HEDP 2 R33 Bosch 1992 Li p He He 60 650 2900 6LIP3HE R33 Marion 1956 SLi p a He 60 650 2900 6LIPA R33 Marion 1956 Li D a He 150 400 1900 6LIDA 1 R33 Maurel 1981 9Li CHe p Be 165 900 5100 6LITPO R33 Schiffer 1956 Li He p Be 165 900 5100 6LITP1 R33 Schiffer 1956 Li p a He 150 500 1500 7LIPA R33 Maurel Be p a Li Total 30 700 OBEPA R33 Sierk 1973 Be p a Li 138 240 1350 9BEPA 1 R33 Thomas 1949 Be p D Be Total 30 700 OBEPD R33 Sierk 1973 Be p D Be 135 780 3000 9BEPD 1 R33 Weber1956 Be p D Be 138 240 1330 9BEPD 3 R33 Thomas1949 Be p D Be 165 1400 1500 9BEPD 2 R33 Mayer 2001 Be D do Li 165 500 1900 9BEDAO R33 Biggerstaff 1962 Be D a Li 165 500 1600 OBEDA1 R33 Biggerstaff 1962 BeCHepy B 90 1800 5100 9BETPO 1 R33 Wolicki BeCHep B 90 1800 5100 OBETP1_1 R33 Wolicki BeCHep B 150 1800 5100 9BETPO 2 R33 Wolicki BeCHe p B 150 1800 5100 OBETP1_2 R33 Wolicki B p ao Be 50 1800 10800 10BPAO 1 R33 Jenkin 1964 _ B p a Be 50 2350 10100 IOBPA1 L R33 Jenkin1964 B p ao Be 90 1800 9500 10BPAO_2 R33 Jenkinl964 _ B
56. 02 A OLE automation reference Create the application object Set App CreateObject Simnra App Create the target object Set Target CreateObject Simnra Target Wait 1000 ms May be necessary for the server to start WScript Sleep 1000 Open a NRA file Result App Open c temp test nra Add an empty layer Will be the last layer Target AddLayer lay Target NumberOfLayers Set the layer thickness to 1000 x 10 atoms cm Target LayerThickness lay 1000 Add one element Will be the last element Target AddElement lay el Target NumberOfElements lay Set the element properties Attention Au already has to be present in an already existing layer Target ElementName lay el Au Target ElementConcentration lay el 1 0 Calculate the spectrum Result App CalculateSpectrum 203 B The R33 cross section file format The R33 cross section file format April 2002 By I C Vickridge Groupe de Physique des Solides UMR 7588 du CNRS Tour 23 Universit s de Paris 7 et 6 2 Place Jussieu 75251 Paris B 1 Introduction In September 1991 in response to the workshop on cross sections for Ion Beam Analysis IBA held in Namur July 1991 Nuclear Instruments and Methods B66 1992 a simple ascii format was proposed to facilitate transfer and collation of nuclear reaction cross section data for Ion Beam Analysis IBA and especially for Nuclear Reaction Analysis NRA Although inten
57. 02 80 28 D A Bromley J A Kuehner and E Almqvist Phys Rev Lett 4 7 1960 365 80 29 DA Bromley J A Kuehner and E Almqvist Phys Rev 123 3 1961 878 80 81 30 J Liu Z Zheng and WK Chu Nucl Instr Meth B 118 1996 24 85 31 J E Ziegler Nucl Instr Meth B 136 138 1998 141 85 32 H Paul A Schinner and P Sigmund Nucl Instr Meth B 164 165 2000 212 85 33 H Paul http www exphys uni linz ac at stopping 85 34 J E Ziegler Stopping Cross Sections for Energetic Ions in all Elements vol 5 of The Stopping and Ranges of Ions in Matter Pergamon Press New York 1980 86 35 J E Ziegler and J M Manoyan Nucl Instr Meth B 35 1988 215 87 88 89 90 36 WH Bragg and R Kleeman Philos Mag 10 1905 318 90 37 D Boutard W M ller and B M U Scherzer Phys Rev B38 5 1988 2988 90 38 D I Thwaites Nucl Instr Meth B 27 1987 293 90 212 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 Bibliography E Szil gyi E P szti and G Amsel Nucl Instr Meth B 100 1995 103 93 94 96 104 107 108 E Szil gyi Nucl Instr Meth B 161 163 2000 37 93 M A Kumakhov and EE Komarov Energy Loss and Ion Ranges in Solids Gordon and Breach Science Publishers New York London Paris 1981 94 J R Bird and J S Williams Eds Ion Beams for Materials Analysis Academic Press
58. 2oREE be se 90 4 604 SRIM Stopping saw reete EE dee the esi wed E we doy ei es 90 46 5 StOppine In el 2 1424 ee a ao Um Ree a ke RR 90 Contents 4 7 Det ct renergy resolution erro EN Xue e a e ee 92 4 7 1 Tie EE AA RRA A 92 Ads Blectrostatie iio hi rd a eg aes 92 4 8 StragPling A EE EE bir dera ra ps a od 93 48 1 OvetvieW e oa u de kc hee a a a Er 93 4 8 2 Electronic energy loss straggling ooo ooo o 94 48 3 Nuclear energy loss straggling supiera eae E 103 4 8 4 Energy lossstragglingincompounds o o 103 4 8 5 Geometrical straggling 2 scole de a cs 103 4 9 Multiple and plural scattering oo ooo o e eee 107 O EE 107 4 9 2 Multiple small angle scattering e REENEN ys 107 49 3 Plural large angle scattering e rai IEEE ee ee A 108 ASO Suriace TOHEDROBS pa im Brel e ao ae Br an NEEN Bem SN AEN 111 4 10 1 Rough film on smooth substrate ANNE o y 9 111 4 10 2 mooth film on a rough substrate llle 116 4 11 Live time and pileup ssr ecu aniba tin nete EXE i NEE UR XU EE 126 ILL lie ume COMECHOM uer 24 9 wks ex RGA GU Ache C EROS Oe ASKS 126 2112 Calcula EE 127 Examples 137 5 1 RBS Rutherford cross sections o 137 5 2 RBS Non Rutherford cross sections eee 140 5 3 ERDA Non Rutherford cross sections 00 eee ee ee eee 142 Acknowledgements 143 OLE automation reference 145 DWIENBLICRuD I DEED 151 er A
59. 31 x 107 0 is the recoil angle in the lab system SIMNRA applies the correction to the Rutherford cross section from Equation 4 17 also for the recoil cross section 79 4 Physics 4 4 2 Non Rutherford cross sections High energy deviations At high energies the cross sections deviate from Rutherford due to the influence of the nuclear force A useful formula above which energy Eyp deviations from Rutherford can be expected was given by Bozoian 25 26 27 M M5 Z Ey MeV 22 forZ 1 sa MeV d fA M M ZiZ Eng MeV m L2 for Z gt 1 2 Eyg is the energy at which the deviation from the Rutherford cross section gets gt 4 SIMNRA does not check if the cross sections at a given energy are Rutherford or not It is in the responsibility of the user to choose the correct cross sections The above formulas may be useful to estimate if the cross section is still Rutherford or not For non Rutherford cross sections SIMNRA uses experimentally determined differential cross sections taken from SigmaBase The use of non Rutherford cross sections is described in full detail in section 3 8 SIMNRA uses linear interpolation between the given data points Mott scattering The scattering of identical particles in forward direction such as He on He C on C 8Si on Si etc results in a quantum mechanical interference term and deviates from Rutherford scattering already at low energies 28 29 This is called Mott scattering and
60. 34 1998 249 111 M Mayer R Behrisch C Gowers P Andrew and A T Peacock Change of the optical reflectivity of mirror surfaces exposed to JET plasmas In Diagnostics for Experimental Thermonuclear Fusion Reactors 2 P Stott G Gorini P Prandoni and E Sindoni Eds Plenum Press New York London 1998 p 279 115 M Mayerz R Behrisch P Andrew and A T Peacock J Nucl Mater 241 243 1997 469 115 214 Bibliography 78 M K stner W Eckstein E Hechtl and J Roth J Nucl Mater 265 1999 22 117 79 M Mayer Nucl Instr Meth B 194 2002 177 118 80 R Amirikas D N Jamieson and S P Dooley Nucl Instr Meth B 77 1993 110 120 140 81 G Amsel E Girard G Vizkelethy G Battistig Y Girard and E Szil gyi Nucl Instr Meth B 64 1992 811 127 82 L Wielopolski and R P Gardner Nucl Instr Meth 133 1976 303 127 130 83 D Cano Ott J L Tain A Gadea B Rubio L Batist M Karny and E Roeckl Nucl Instr Meth A 430 1999 488 130 84 C Jeynes Z H Jafri R P Webb A C Kimber and M J Ashwin Surface and Interface Analysis 25 1997 254 132 85 J Vorona J W Olness W Haeberli and H W Lewis Phys Rev 116 1959 1563 140 86 M Wielunski M Mayer R Behrisch J Roth and B M U Scherzer Nucl Instr Meth B 122 1997 113 142 87 J E E Baglin A J Kellog M A Crockett and A H Shih Nucl Instr Meth B 64 1992 469 142 88 E Besenba
61. 340 3000 HC135 MAZZONLR33 Mazzoni 1998 C ppC 140 340 3000 HC140 MAZZONLR33 Mazzoni 1998 C p p C 145 340 3000 HC145_MAZZONI R33 Mazzoni 1998 C p p C 150 340 3000 HC150 MAZZONLR33 Mazzoni 1998 C p p C 150 1000 3500 12CPPC 1 R33 Amirikas 1993 C ppC 155 340 3000 HC155 MAZZONLR33 Mazzoni 1998 C p p C 160 340 3000 HC160 MAZZONLR33 Mazzoni 1998 C p p C 165 340 3000 HC165 MAZZONLR33 Mazzoni 1998 C p p C 165 100 3500 HC165_GURBICH R33 Gurbich 1998 C p p c 165 1000 3500 12CPPC R33 Amirikas 1993 C p p C 170 340 3000 HC170 MAZZONLR33 Mazzoni 1998 C ppC 170 300 700 PC_LI93A RTR Liu 1993 C p p C 170 700 2800 PC_LI93B RTR Liu 1993 C p p C 170 300 3000 PC_LI93C RTR Liu 1993 C p p C 170 700 2500 PC_RA85A RTR Rauhala 1985 C ppC 170 996 3498 PC_AM93A RTR Amirikas 1993 C p p C 170 1000 3500 12CPPC_2 R33 Amirikas 1993 Po pp C 179 2 4000 6600 12CPP179 R33 Tosaki 2000 PO pp C 168 2 400 4500 PC_JA53A RTR Jackson 1953 AN p p N 140 500 2500 HN140_RAMOS R33 Ramos 2002 M4N p p 4N 150 800 1900 PN_TA56A RTR Tautfest 1956 14N p p N 152 1035 1075 PN_HA57A RTR Hagedorn 1957 MN p p N 152 1450 1625 PN HA57B RTR Hagedorn 1957 P N p p N 152 650 1800 PN_HA57E RTR Hagedorn 1957 N p p N 1552 1850 3000 PN LA67A RTR Lambert 1967 N pp N 1587 1735 1760 PN_HA57C RTR Hagedorn 1957 N pp N 1587 1785 1815 PN HA57D RTR Hagedorn 1957 MN p p N 159 5 600 4000 PN BA59A RTR Bashkin 1959 PLN p p N 165 1850 300
62. 6 77 Bibliography P Sigmund and K B Winterbon Nucl Instr Meth 119 1974 541 107 A D Marwick and P Sigmund Nucl Instr Meth 126 1975 317 107 E Szil gyi DEPTH for targets containing multilayers http www kfki hu ionhp doc prog mdepth htm 108 M Mayer K Arstila K Nordlund E Edelmann and J Keinonen Nucl Instr Meth B 249 2006 823 108 R D Edge and U Bill Nucl Instr Meth 168 1980 157 111 A R Knudson Nucl Instr Meth 168 1980 163 111 J R Bird P Duerden D D Cohen G B Smith and P Hillery Nucl Instr Meth 218 1983 53 111 C P Hobbs J W McMillan and D W Palmer Nucl Instr Meth B 30 1988 342 111 M W est and P Bochsler Nucl Instr Meth B 71 1992 314 111 I M Yesil Einfluf der Oberflachenrauhigkeit auf ERDA Tiefen Profile Master s thesis Ludwig Maximilian Universit t M nchen 1995 In german 111 I M Yesil W Assmann H Huber and K E G L bner Nucl Instr Meth B 136 138 1998 623 111 A Kitamura T Tamai A Taniike Y Furuyama T Maeda N Ogiwara and M Saidoh Nucl Instr Meth B 134 1998 98 111 R Behrisch S Grigull U Kreissig and R Gr tschel Nucl Instr Meth B 136 138 1998 628 111 VS Shorin and A N Sosnin Nucl Instr Meth B 72 1992 452 111 H Metzner M Gossla and Th Hahn Nucl Instr Meth B 124 1997 567 111 H Metzner Th Hahn M Gossla J Conrad and J H Bremer Nucl Instr Meth B 1
63. 600 800 1000 1200 1400 1600 1800 e experimental simulated 2000 Counts 100 200 300 400 500 600 700 800 Channel o Figure 5 4 2000 keV protons backscattered from silicon a 5 0 165 141 5 Examples Energy keV 600 800 1000 1200 1400 1600 1800 a Exp SIMNRA 200 Set ee H 150 YN S 3 100 Q 50 0 a Meg oe 100 200 300 Channel Figure 5 5 ERDA with 2 6 MeV He ions incident on a soft amorphous hydrocarbon layer a C H layer containing both H and D The recoiling H and D atoms were separated with a AE E telescope detector the backscattered He ions are not shown a fl 75 0 30 5 3 ERDA Non Rutherford cross sections Figure 5 5 shows the measured and simulated spectra for ERDA with 2 6 MeV incident He ions on a soft amorphous hydrocarbon layer a C H layer containing both H and D The recoiling H and D atoms were separated with a AE E telescope detector 86 Both recoil cross sections are non Rutherford The cross section data of Baglin et al 87 for H He H He and of Besenbacher et al 88 for D He D He were used for the simulation The peak in the deuterium spectrum is due to a resonance at a He energy of 2130 keV The measured and simulated data agree very well 142 6 Acknowledgements any cross section data files included with SIMNRA have been taken from SigmaBase http ibaserver physics isu edu sigmabase which is maintained by I Vickridge See the file h
64. 9FPA 1 R33 Dieumegard 1980 IP E p a 90 150 700 2000 19FPA 2 R33 Dieumegard 1980 PE D ag O 150 700 1900 19FDAO 1 R33 Maurel 1981 PE D a O 150 1000 1900 19FDA1 1 R33 Maurel 1981 1E a py Ne 135 2160 2520 F19APOT135 R33 Borgardt 1998 1E a p 2Ne 135 2160 2520 F19AP1T135 R33 Borgardt 1998 BsiPHe p JP 28SITPO R33 Groeneveld 1970 8Si He p P 28SITP1 R33 Groeneveld 1970 T He pp 28SITP2 R33 Groeneveld 1970 35Si CHe p P 28SITP3 R33 Groeneveld 1970 8Si Hen P 28SITP4 R33 Groeneveld 1970 32S D pJ S 150 1000 2700 32SDPR33 Healy 1998 32S D p S 150 1000 2700 32SDP1 R33 Healy 1998 D p S 150 1000 2700 32SDP2 R33 Healy 1998 32S D p3 S 150 1000 2700 32SDP3 R33 Healy 1998 9 D p s S 150 1000 2700 32SDP456 R33 Healy 1998 3 Using SIMNRA 0 Lab Energy keV File Reference 32S D p S 150 1000 2700 32SDP7 R33 Healy 1998 46 3 Using SIMNRA Old File New File Version Reason for replacement 10B3Hep0_135 r33 B10He3p0t135 r33 5 10 Better accuracy 10B3Hep0_90 r33 B10He3p0t90 r33 5 10 Better accuracy 10B3Hepl 135 133 B10He3p1t135 r33 5 10 Better accuracy 10B3Hepl 90 r33 B10He3p1t90 r33 5 10 Better accuracy 11B3HepO 135 133 B11He3p0t135 r33 5 10 Better accuracy 11B3HepO 90 r33 B11He3p0t90 r33 5 10 Better accuracy 14N3HepO 135 133 N14He3p0t135 r33 5 10 Better accuracy 14N3HepO 90 r33 N14He3p0t90 r33 5 10 Better accuracy 14N3Hep12_135 133 N14He3p1 2t135 r33 5 10 Bet
65. A pile up rejector PUR is only able to recognize two pulses as different if their time difference is larger than the pair resolution time The pair resolution time is normally specified in the technical manual of the pile up rejector Typical values are in the range 0 3 0 5 us Note This parameter is only available if the pile up model is set to Accurate in the Setup Calculation menu This parameter has no influence if the pile up model is set to Fast 20 3 Using SIMNRA 3 6 3 Setup Calculation In the Setup Calculation menu the calculation parameters can be altered This affects the accuracy of the calculation but also the time necessary to calculate a simulated spectrum Parameter tab Isotopes If checked backscattering from all isotopes of all elements in the target is calculated Especially for heavy elements with many isotopes this will slow down the calculation significantly If unchecked the program will use only the mean masses of the elements Default is checked Important Non Rutherford cross sections and nuclear reactions are only available if Isotopes is checked Straggling If checked electronic energy loss straggling and geometrical straggling if selected see section 3 6 2 is taken into account Default is checked Multiple Scattering If checked straggling due to multiple small angle scattering will be calculated Default is unchecked Dual Scattering Most particles are scattered into the dete
66. A rough layer is approximated by the superposition of N spectra with different layer thicknesses where N is the number of thickness steps If N is small the superposed spectrum may contain steps Larger values of N result in smoother spectra but slow down the calculation considerably Default is N 10 Note One rough layer requires the calculation of N spectra two rough layers of N spectra three rough layers of N spectra etc Number of angular steps Used for the calculation of substrate roughness A rough substrate is approximated by the superposition of M spectra with different incident and exit angles where M is the number of angular steps If M is small the superposed spectrum may contain steps Larger values of M result in smoother spectra but slow down the calculation considerably Default is M 20 26 3 Using SIMNRA Note Substrate roughness requires the calculation of M spectra one rough layers combined with substrate roughness of N x M spectra where N is the Number of thickness steps two rough layers combined with substrate roughness of N x M spectra etc Dimension of substrate roughness Specifies if a 2 dimensional or an almost 3 dimensional 2 5 dimensional model of substrate roughness is used See subsection 4 10 2 for details The 2 5 dimensional model is more realistic and the program default The File menu allows to save setups for calculations to disk and read setups from disk AII information co
67. App SpectrumChanged 155 DeleteSpectrumOnCalculate Get Set Property DeleteSpectrumOnCalculate Boolean Default Value true Description If DeleteSpectrumOnCalculate is true the current simulated spectrum is deleted before a new spectrum is calculated If false the current simulated spectrum is conserved and the new spectrum is added to the current one Default is true Example Spectrum for scattering angle 160 Setup Theta 160 App CalculateSpectrum Spectrum for scattering angle 170 is now added to the previous spectrum App DeleteSpectrumOnCalculate false Setup Theta 170 App CalculateSpectrum Related Properties and Methods App CalculateSpectrum 156 152 A OLE automation reference FileName Get Property FileName WideString Description Name of the currently used nra file including full path FileName is readonly If you want to change FileName you have to open or save an nra file Related Properties and Methods App Open 161 App SaveAs 163 Height Get Set Property Height Integer Description Height of the main form in pixels Related Properties and Methods App Left 154 App Top 155 App Width 155 LastMessage Get Property LastMessage WideString Description Text of the last error message or warning LastMessage is retained until a new error or warning is issued or it is read with LastMessage LastMessage is readonly See section A 9 for more details about
68. B RTR Langley 1976 3He p p He 2000 3000 PHELA76A RTR Langley 1976 He p p He 1500 3700 PHELA76B RTR Langley 1976 SLi p p Li 1200 3100 PLIBA51A RTR Bashkin 1951 Li p p Li 373 1398 PLIWA53A RTR Warters 1953 eu 1700 3500 PLIBA51B RTR Bashkin 1951 Li p p Li 1300 2800 PLIMA56A RTR Malmberg 1956 Be p p Be 1600 3000 PBEMOS6A RTR Mozer 1956 Be p p Be 200 1700 PBEMOS6B RTR Mozer 1956 Be p p Be 2400 2700 PBELE94A RTR Leavitt 1994 B p p B 800 3300 H10B100_CHIARI R33 Chiari 2001 B p p B 800 3300 H10B105_CHIARI R33 Chiari 2001 B p p B 725 3300 H10B110_CHIARI R33 Chiari 2001 10B p p B 625 3300 H10B115 CHIARLR33 Chiari 2001 1B p p B 650 3300 H10B120 CHIARLR33 Chiari 2001 1B p p B 600 3300 H10B125_CHIARI R33 Chiari 2001 B p p B 500 3300 H10B130_CHIARI R33 Chiari 2001 B p p B 500 3300 H10B135_CHIARI R33 Chiari 2001 10B p p B 500 3300 H10B140_CHIARI R33 Chiari 2001 I B p p B 500 3300 H10B145 CHIARLR33 Chiari 2001 B p p B 500 3300 H10B150 CHIARLR33 Chiari 2001 10B p p B 1000 3000 PB OV62A RTR Overley 1962 B p p B 500 3300 H10B155 CHIARLR33 Chiari 2001 10B p p B 500 3300 H10B160 CHIARLR33 Chiari 2001 1B p p B 165 500 3300 H10B165_CHIARI R33 Chiari 2001 I B p p B 170 500 3300 H10B170 CHIARLR33 Chiari 2001 B pp B 100 800 3300 H11B100_CHIARI R33 Chiari 2001 B pp B 105 825 3300 H11B105 CHIARLR33 Chiari 2001 T B p p B 110 725 3300 H11B11
69. CTP0_1 R33 Kuan 1964 PCCHep N 159 4 1800 5400 12CTP1_1 R33 Kuan 1964 PCCHep N 159 4 1800 5400 12CTP2_1 R33 Kuan 1964 Ce aal C 159 4 1800 5400 12CTAO R33 Kuan 1964 I3C D p C 135 600 2950 13CDPR33 Marion 1956 PBCCHe p N 150 1900 3800 13CTP0 R33 Illsley 1957 PCCHe p N 13CTP12 R33 Illsley 1957 C He p N 13CTP3 R33 Illsley 1957 NOD ay C 150 600 1400 14NDAO_1 R33 Amsel 1969 14N D a 1C 150 600 1400 14NDA1_1 R33 Amsel 1969 14N D po N 150 500 1900 14NDPO 1 R33 Simpson 1984 NOD pj 3 N 150 600 1400 14NDP12 R33 Amsel 1969 PN D p3 PN 150 800 1400 14NDP3 R33 Amsel 1969 N D p N 150 600 1400 14NDP45 R33 Amsel 1969 14N D p 5N 150 600 1400 14NDP45 R33 Amsel 1969 NC He po O 90 2000 4000 N14HE3P0T90 R33 McIntyre 1996 NC He po 0 135 2000 4000 N14HE3P0T135 R33 McIntyre 1996 ANC He p 2 0 90 2000 4000 N14HE3P1 2T90 R33 McIntyre 1996 ANC He p 2 0 135 2000 4000 N14HE3P1 2T135 R33 McIntyre 1996 ANC He p3 4 60 90 2000 4000 N14HE3P3 4T90 R33 McIntyre 1996 PNC Hep3 4 0 135 2000 4000 N14HE3P3 4T135 R33 McIntyre 1996 ANC He p12 40 90 1600 2800 14NTP1X1 R33 Terwagne 1994 ANC He p 2 0 135 1600 2800 14NTP1X2 R33 Terwagne 1994 ANC He p 0 90 1600 2800 14NTP3X1 R33 Terwagne 1994 Using SIMNRA 0 Lab Energy keV File Reference MNCHe p3 0 135 1600 2800 14NT
70. Cj are fitting coefficients and tabulated in the file SCOEE95B For energies below 10 keV amu the electronic stopping power S is given by S E S 10 4 42 where S 10 is the stopping power at 10 keV amu and y 0 45 for Z gt 6 and y 0 35 for Z5 6 Nuclear stopping for incident hydrogen deuterium and tritium ions is negligible for incident energies above about 10 keV amu 3 and is neglected by SIMNRA Helium If Ziegler Biersack stopping is selected then for incident He and He ions the electronic stopping power data by Ziegler Biersack and Littmark 5 are used for all elements The electronic stopping of He ions in elements S is derived from the stopping power of protons for the same velocity S by using 5 35 S Sp eZee 4 43 Zu is the helium charge and ro can be obtained from the simple polynomial fit 5 on 1 exp BH 4 44 i 0 with E in keV amu The coefficients C are tabulated in 35 Nuclear stopping for incident helium ions is calculated with the universal ZBL potential 5 The nuclear stopping S in eV 10 atoms cm for He ions with incident energy E in keV is given by 8 462 Z Z4 Mi ay eee a es 4 45 Mi M3 aa SCH n Sn is the reduced nuclear stopping and Z4 M are the nuclear charge and mass of the helium ion and Z5 M are the nuclear charge and mass of the target element The reduced nuclear stopping s has the simple form In 1 1 1383 TRE 4 46 2
71. ICH93A RTR Cheng 1993 Si a a Si 170 6000 9000 ASICH93B RTR Cheng 1993 8Si o q 5Si 165 2400 4000 ASILE72A RTR Leung 1972 25Si a a 5Si 165 4000 5000 ASILE72B RTR Leung 1972 B5i a a PSi 165 5100 6000 ASILE72C RTR Leung 1972 ac AE 165 2400 5000 ASILE72D RTR Leung 1972 7Al a a Al 170 2000 9000 AALCH93A RTR Cheng 1993 Cl a a Cl 165 2000 9000 ACLCH93A RTR Cheng 1993 Ar a a Ar 170 1800 5200 AARLE86A RTR Leavitt 1986 K a a K 175 5 6000 8000 AK FR82A RTR Frekers 1982 Ca a a Ca 166 2200 8800 ACAHU9OA RTR Hubbard 1990 Ca a a Ca 145 5000 9000 ACASE87A RTR Sellschop 1987 40 3 Using SIMNRA 0 Lab Energy keV File Reference C 6Li 8Li C 165 1800 4700 C6LiLiC R33 Mayer 2001 I9E 61 61j I F 150 2500 7000 19F6LiLiER33 Pastuovi 1998 27 AJ Li Li AI 140 4000 8000 Nurmela 6Li Al 140 R33 Nurmela 1999 27 AJ SLi Li AI 170 4000 8000 Nurmela 6Li Al 170 R33 Nurmela 1999 SiCLi Li Si 140 4500 7750 Nurmela 6Li Si_140 R33 Nurmela 1999 Si 9Li 9Li Si 170 4500 7750 Nurmela 6Li Si 170 R33 Nurmela 1999 Ti Li LO Ti 140 5000 11000 Nurmela 6Li Ti 140 R33 Nurmela 1999 Ti Li SLOT 170 5000 11000 Nurmela 6Li Ti_170 R33 Nurmela 1999 CC Li Li C 2900 5400 C7LiLiC R33 Mayer 2001 Ie07Li 7Li 50 170 2750 6250 1607LiLiO R33 Rauhala 1988 27 AIC Li
72. KKK stopping for H D T He and He in C and Si Nuclear stopping is calculated using the universal potential see subsection 4 6 2 4 6 4 SRIM stopping SRIM is a program for calculating stopping powers of ions ions matter SRIM stopping is obtained by calling the SRIM program which has to be downloaded and installed separarely See the SRIM documentation for details of stopping power calculations 4 6 5 Stopping in compounds SIMNRA uses Bragg s rule 36 for the determination of the stopping power in compounds Bragg s rule is a simple linear additivity rule of the stopping contributions of the different compound elements assuming that the interaction of an incident ion with a target atom is independent of the surrounding target atoms For a compound consisting of different elements i with atomic concentrations c c 1 the total stopping power S is given by s gi 4 50 S is the stopping power of each element Bragg s rule assumes that the interaction between the ion and the atom is independent of the environment The chemical and physical state of the medium is however observed to have an effect on the energy loss The deviations from Bragg s rule predictions are most pronounced around the stopping power maximum and for solid compounds such as oxides nitrides and hydrocarbons The deviations from Bragg s rule predictions may be of the order of 10 2096 35 37 For compounds with heavier atoms such as Fe505 NbC NbN Ta205
73. O51ERTR Mooring 1951 Mg p pMg 164 1642 1671 PMGMO51G RTR Mooring 1951 4Mg p p Mg 164 1991 2026 PMGMO51H RTR Mooring 1951 24Mg p p Mg 164 2393 2431 PMGMO51I RTR Mooring 1951 Mg p pMg 170 700 2540 PMGRA88A RTR Rauhala 1988 Al p p Al 140 500 2500 HAL140_RAMOS R33 Ramos 2002 Zait Al 140 800 3000 HAL140_CHIARI R33 Chiari 2001 7Al p p Al 150 800 3000 HAL150_CHIARI R33 Chiari 2001 Zait Al 160 800 3000 HAL160_CHIARI R33 Chiari 2001 7A1 p p 7Al 165 800 3000 HAL165_CHIARI R33 Chiari 2001 7Al p p Al 170 800 3000 HAL170_CHIARI R33 Chiari 2001 7Al p p Al 170 1000 2450 PALRA89A RTR Rauhala 1989 T Al p p Al 178 500 2500 HAL178_RAMOS R33 Ramos 2002 Si p p Si 160 1500 2100 HSI160 SALOMONOVIC R33 Salomonovic 1993 Si p p Si 165 1000 3000 HSI165_GURBICH R33 Gurbich 1998 8Si p p Si 167 2 1300 4000 PSIVO59A RTR Vorona 1959 Si p p Si 170 1500 2000 HSI170 SALOMONOVIC R33 Salomonovic 1993 Si p p Si 170 1000 3500 SIPPSI R33 Amirikas 1993 Si p p Si 170 1000 3580 PSIAM93A RTR Amirikas 1993 Si p p Si 170 1470 2200 PSIRA85A RTR Rauhala 1985 3 p p p P 165 1000 2000 PP_CO63A RTR Cohen Ganouna 1963 32S p p S 167 4 1300 4000 PS_OL58A RTR Olness 1958 S p p S 170 1500 2690 PS_RA88A RTR Rauhala 1988 Cl p p Cl 150 2000 5000 PCLBO93A RTR Bogdanovic 1993 38 3 Using SIMNRA Energy keV File Reference Ar p p Ar 159 5 1800 3600 PARBK61A RTR Barnhard 1961 40 Ar p p Ar 166
74. P3X2 R33 Terwagne 1994 MN He p O 90 1600 2800 14NTP4X1 R33 Terwagne 1994 N He py 20 135 1600 2800 14NTP4X2 R33 Terwagne 1994 N He ps 0 90 1600 2800 14NTP5X1 R33 Terwagne 1994 NCHe ps O 135 1600 2800 14NTP5X2 R33 Terwagne 1994 NCHe py O 90 1600 2800 14NTP7X1 R33 Terwagne 1994 N He p 0 135 1600 2800 14NTP7X2 R33 Terwagne 1994 NCHe ag PN 90 1600 2800 14NTAOX1 R33 Terwagne 1994 NCHe ag PN 135 1600 2800 14NTAOX2 R33 Terwagne 1994 MN apo O 135 4000 5000 14NAP1 R33 Giorginis 1995 BN p a ec 140 900 2860 15NPA R33 Hagedorn 1957 5N D a C 90 400 1600 15NDA90 R33 Vickridge 1996 PND cC 135 400 2000 15NDA135 R33 Vickridge 1996 5N Da C 150 400 2000 15NDA150 R33 Vickridge 1996 PN D a C 150 800 1300 15NDA 1 R33 Sawicki 1985 160 D a 4N 135 800 2000 160DA_2 R33 Amsel 1964 O D a N 145 760 950 160DA 1 R33 Turos 1973 O D a N 165 800 2000 16ODA 3 R33 Amsel 1964 50 D p 7O 135 20 3000 16ODPO 1 R33 Jarjis 1979 160 D p 7O 135 500 3000 160DP1_2 R33 Jarjis 1979 10 D p O 155 400 1100 160DP1_1 R33 Amsel 1967 1604 He a YO 90 1600 2600 160TA R33 Abel 180 p a N 155 1500 1800 180PA_2 R33 Alkemada 150 p q N 165 500 1000 180PA_1 R33 Amsel 1967 150 D q 9N 165 830 2000 18ODA 1 R33 Amsel 1964 150 D g 16N 165 830 2000 180DA_2 R33 Amsel 1964 180 D a EN 165 830 2000 18ODA 3 R33 Amsel 1964 180 D a 5N 165 830 2000 18ODA 4 R33 Amsel 1964 IP E p a 90 90 700 1900 1
75. RegionMaxChannel 191 191 A OLE automation reference A 6 2 Methods Chi2 Function Chi2 Double Description Quadratic deviation y between the simulated and measured data points see subsection 3 9 1 y is weighted with the statistical error of the experimental data y is calculated only in the fit regions defined by NumberOfRegions Region MaxChannel and RegionMinChannel Chi2 can be used to develop your own fit algorithms Parameters None Return Value Returns zi Related Properties and Methods Fit NumberOfRegion 190 Fit RegionMaxChannel 191 Fit RegionMinChannel 191 A 7 Simnra Spectrum The Simnra Spectrum object represents experimental and simulated spectra and allows to change plot parameters A 7 1 Input parameter The properties and methods of Simnra Spectrum require the input parameter spID which specifies if the experimental or simulated spectrum is accessed The possible values for spID are spID Selected spectrum 1 Experimental data 2 Simulated data 192 A OLE automation reference Other values are not allowed A 7 2 Properties AutoScale Get Set Property AutoScale Boolean Default Value true Description If AutoScale is true the plot is scaled automatically if experimental data are imported or a new calculation is performed If false the axis scales remain fixed BottomAxisMax Get Set Property BottomAxisMax Double Description Bottom axis maximum
76. Si scattering angle 165 Circles experimental data points dashed line simulation with one scattering event solid line simulation with two scattering events 139 5 Examples Energy keV 400 600 800 1000 1200 1400 14000 e experimental simulated 12000 10000 8000 6000 Counts 4000 2000 100 200 300 400 500 600 Channel Figure 5 3 2000 keV protons on carbon HOPG a 5 0 165 5 2 RBS Non Rutherford cross sections Figure 5 3 shows the measured and simulated spectra for 2 0 MeV protons incident on highly oriented pyrolytic graphite HOPG To avoid channelling the incident angle a was 5 The cross section is non Rutherford and the cross section data of Amirikas et al 80 were used for the simulation The pronounced peak in the spectrum is due to the resonance in the C p p C cross section at 1732 keV The measured and simulated spectra agree very well Figure 5 4 shows the measured and simulated spectra for 2 0 MeV protons incident on silicon To avoid channelling the incident angle a was 5 The cross section is non Rutherford and the cross section data of Vorona et al 85 were used for the simulation As in the case of carbon the measured and simulated spectra agree very well The structures in the simulated spectrum between channel 500 and 700 are due to the experimentally determined cross section data which contain these structures 140 5 Examples Energy keV 400
77. Target DeleteLayer 185 DeleteLayer Function DeleteLayer lay Integer Boolean 184 A OLE automation reference Description Deletes layer number lay Parameters lay Number of the layer to delete with 1 lt lay lt NumberOfLayers Return Value Returns true if the layer was deleted successfully Related Properties and Methods Target DeleteElement 184 InsertLayer Function InsertLayer lay Integer Boolean Description Inserts a new layer in front of layer number lay The layer has zero thickness and contains no elements After inserting a layer at least one element has to be added with AddElement and layer properties like thickness roughness etc have to be set Parameters lay Number of the layer with 1 X lay NumberOfLayers Return Value Returns true if the layer was inserted successfully Related Properties and Methods Target AddLayer 183 ReadTarget Procedure ReadTarget FileName WideString 185 A OLE automation reference Description Reads a target description from file FileName The current target is replaced by the content of FileName FileName must be either a valid nra or target description file Parameters FileName Name of the file including path Related Properties and Methods Target SaveTargetAs 186 SaveTargetAs Procedure SaveTargetAs FileName WideString Description Saves the target description to file FileName Parameters FileName Name of
78. These data are identical to Ziegler s SRIM 1997 formerly TRIM program The Ziegler Biersack data are generally more accurate and reliable than the Andersen Ziegler data 6 The energy ranges in which the different stopping power formulas are valid are listed in Table 3 2 ZB KKK Identical to Ziegler Biersack for most ion target combinations except for H D T He and He in C and Si in which case the stopping power data by Konac et al 7 8 are used The KKK stopping powers are valid in the energy range 0 01 E 100 MeV amu See subsection 4 6 3 for details about the KKK stopping powers SRIM Stopping power data from Ziegler s SRIM program version SRIM 2003 or later This option will work only if 1 SRIM is installed on your computer 2 the path to the SRIM directory is registered correctly in Options Preferences Directories See section 3 17 for more details User defined User defined stopping powers are used See section 3 18 for details But note that you have to supply stopping power data for all elements present in the target if User defined stopping powers are selected High energy stopping This switch is only available if Andersen Ziegler electronic stopping power data are used If checked the program will use the correct high energy stopping 22 3 Using SIMNRA formula by Andersen and Ziegler for incident protons and heavy ions for E gt 1 MeV amu If unchecked the program will use the
79. When the energy losses become very large and the mean energy of the beam decreases below the energy of the stopping power maximum the particle energy distribution again become skewed because now particles with lower energy have a lower stopping power than particles with higher energy The distribution is about Gaussian SIMNRA always assumes that the particles energy distribution is Gaussian This is only an approximation for thin layers In this case the energy distribution is described by the Vavilov distribution 44 42 However the straggling contribution of thin layers to the total energy broadening is much smaller than the contribution of the finite energy resolution of the detector SIMNRA calculates the non statistic broadening or skewing of the energy distribution when penetrating a layer in the following way 39 Assume two particles with energies E and E E Eat 1 d 2 E E a S 2 centered around a mean energy Eg The energy difference E E of the two particles is AE After penetrating a layer the particles have the energies E and E centered around a mean 94 4 Physics energy Ej The energy difference AE behind the layer is given by Ef EC zt Ey E q AE 4 54 AE with the stopping power e dE dx e is the stopping power at the exit of the layer and e the stopping power at the entrance of the layer If es gt ej which is the case for all energies above the stopping power maximum the energy di
80. a recoil is given in the laboratory system by Biesen cos 0 6 oTM M5 COS 4 6 Ez Eg is the energy of the incident projectile M the mass of the projectile M the mass of the target nucleus initially at rest and 0 the recoil angle with 0 lt 0 lt 90 4 2 2 Nuclear reactions For the calculation of nuclear reactions kinematics we use the quantities listed in Table 4 1 We define the following quantities MM Ei M M3 Ms M4 Er 74 4 Physics Mass Energy Incident ion Mi Ei Target nucleus M 0 Light product M3 E3 Heavy product Ma E4 Energy released in reaction Q Total energy Er E 0Q E3 E Table 4 1 Quantities used for the calculation of nuclear reactions kinematics The target nucleus is initially at rest For exotherm reactions Q gt 0 for endotherm reactions Q lt 0 A VM E 14 70 M M3 Ms M4 Er M2M3 Mi Q T E E i CNN MNT M M5 Ms M4 M Er M2M Mi Q fe E i Nd M M35 Ms M4 M Er The energy E of the light product created in the nuclear reaction is then given in the laboratory system by A24 3 Hm Ez ErA 3 cos 0 sin 0 4 7 A13 0 is the emission angle of the light product in the laboratory system For A44 lt A34 only the plus sign in Equation 4 7 applies If 413 gt A54 then eq 4 7 has two solutions and the maximum possible emission angle Omax of the light product is Ag i Omax arcsin E 4 8 A13 The energy
81. and more different see the curves for c 0 3 and 0 7 in Figure 4 16 For O d the Gamma distribution decreases exponentially with p d e and for o gt d an integrable singularity develops at d O A RBS NRA or ERDA spectrum of a rough film is approximated by a superposition of N spectra with different layer thicknesses d N can be adjusted by the Number of thickness steps in the Setup Calculation menu see subsection 3 6 3 Typically about N 20 sub spectra are necessary to obtain a smooth superposition though N has to be increased to about N 50 for broad distributions with o gt d The weight w of each sub spectrum is determined according to the thickness distribution function For each sub spectrum the layer is treated to be smooth with thickness d Correlation effects such as incidence through a hump and emergence through a valley or multiple surface crossings are neglected This is only correct for backscattering at a scattering angle of exactly 180 and for transmission geometries However for scattering 112 4 Physics Distribution Gamma Figure 4 16 Comparison of Gaussian distribution functions centered at 1 dashed lines and Gamma distribution functions solid lines with mean value d 1 and different standard deviations c angles in the range 150 180 and non grazing incidence and emergence angles as are used in many RBS and NRA setups correlation effects still play only a minor role and can be
82. and scattering angle 0 a and f are measured towards the surface normal see Figure 3 3 All angles in degrees Note 1 0 lt a lt 90 Note 2 0 lt 6 lt 180 If 90 lt P lt 180 then transmission through the target is calculated Note 3 In most experimental setups either IBM or Cornell geometry is used See Figure 3 10 for a schematic representation of both geometries You can use Calculate Exit Angle Beta to calculate f for IBM and Cornell geometry see section 3 9 Calibration Conversion from channels to energy To account for detector nonlinearities SIMNRA can use a non linear energy calibration with a quadratic term of the form E keV A B x channel C x channel 3 1 E is the particle energy in keV The calibration offset A must be entered in the Calibration Offset field A in keV The energy per channel B must be entered in the Energy per Channel field B in keV channel C is the quadratic correction term C in keV channel For a linear energy calibration C 0 0 A linear calibration is appropriate in most cases and only if a high accuracy is intended a non linear calibration should be used More energy calibration options An individual energy calibration may be used for each ion species This is mainly useful for ERDA measurements with incident heavy ions where each recoil species may require an individual calibration By clicking the button an individual nonlinear energy calibration for each
83. and the surface normal are in the same plane see Figure 3 10 and f is simply given by f 180 a 6 In Cornell geometry incident beam exit beam and the sample rotation axis are in the same plane and f is given by cos fj cos 0 cosa Subtract Pile up Calculates the pile up contribution not from simulated but from experimental data and allows to subtract the pile up from the data See subsection 3 9 2 for details 48 3 Using SIMNRA IBM Cornell Figure 3 10 IBM and Cornell geometry 3 9 1 Fit Spectrum Data fitting to backscattering spectra is a nontrivial task In data fitting the quadratic deviation of the simulated from the measured data points AMA y ent MO i58 is minimized by varying the input parameters of the calculation N i is the number of counts in the measured spectrum N i the number of counts in the simulated spectrum and o the statistical error i can be either individual channels or channel regions see the parameter Chi2 evaluation Fast fitting algorithms such as the Levenberg Marquardt algorithm tend to be unstable and require the knowledge of the derivatives of y SIMNRA uses the Simplex algorithm for fitting 10 11 12 The Simplex algorithm is very stable and converges nearly always However the convergence is not very fast The Simplex algorithm always uses n 1 points called vertices in the parameter space for fitting where n is the number of fr
84. as calculated by Ziegler 5 and is also used by Yang The extra contribution to energy straggling Ac of helium and heavy ions is fitted by Ao EE a h 4 63 HI o 7 m 6 7 C2 t r l with TC exp C44 4 64 and 8 E i 59 where E and 6 are the energies in MeV amu and C4 C are fitted constants The above equations are for solid targets Figure 4 7 compares the beam width FWHM of 2 5 MeV He ions in silicon calculated by SIMNRA using Equation 4 57 with Bohr s theory For small energy losses the beam width calculated by SIMNRA is slightly smaller than predicted by Bohr s theory due to the Chu correction However this is counterbalanced by the nonstochastic broadening due to the characteristics of the stopping power curve and for larger energy losses the beam width gets larger than in Bohr s theory When the mean beam energy has decreased below the energy of the stopping power maximum the beam width becomes skewed As can be seen from Figure 4 6 the deviation of the Chu correction from Bohr s theory is largest for high Z and low energies Figure 4 8 shows the beam width FWHM of 1 MeV He penetrating through gold The deviation from Bohr s theory is large The stopping power maximum is at about 960 keV For low energy losses the beam width increases due to the statistical broadening because the nonstochastic skewing which occurs for beam energies below the stopping power maximum is small and the stochastic broadening wins F
85. ases the Fast model already gives good results especially if a pile up rejector is used and the pulse rise time is larger than about 1 us The Accurate model should be used only if necessary Accurate model The effect of pulse pile up is shown schematically in Figure 4 26 Two overlapping pulses with heights i and j may be interpreted by the analyzing system as corresponding to a fictitious event with height k and the ADC assigns to it an erroneous energy value We will treat only double pulse pile up i e the pile up of exactly two pulses while triple and other multiple pulse pile up will be not considered under realistic conditions for RBS or NRA other than double pulse pile up is not observed 81 The effect of pile up on a single peak is shown schematically in Figure 4 27 Two pulses arriving almost simultaneously result in a sum pulse with almost double height Increasing time lag between the two pulses give sum pulses with heights between the original and the double height resulting in a pile up spectrum which extends from the original peak to the doubled channel number The mathematical models for pile up calculations were already developed in the Seventies and we adopt the model by Wielopolski and Gardner 82 This model was initially developed for Gaussian shaped pulses which are used by analog amplifiers The model is also valid 127 4 Physics Amplitude Time Figure 4 26 Pile up of a pulse with height i an
86. btained by calculating the scattering angle in the centre of mass system cy from Ocm 0 arcsin M M sin 0 zt calculating the Rutherford backscattering cross section in the centre of mass system and transforming into the laboratory system 4 17 FAndersen 78 4 Physics 2000 keV 1000 keV 500 keV 250 keV c ui LL 0 30 60 90 120 150 180 0 degree Figure 4 2 Angular dependence of the correction factors for the Rutherford cross section by L Ecuyer Equation 4 16 dashed lines and Andersen Equation 4 17 solid lines for He backscattered from gold at different energies Ocy is the scattering angle in the center of mass system The increase in the kinetic energy Vj is given by B 2 3 42 3 1 2 Vi kev 0 04873 Z1Z2 Zi Z The dependence of the correction factor F Andersen from the scattering angle 0 for He scattered from gold is shown in Figure 4 2 for different He energies Dashed lines are the angular independent correction factor by L Ecuyer For large scattering angles the correction factors by LEcuyer and Andersen are near to unity and similar however for small scattering angles the correction by Andersen becomes large and the angle independent LEcuyer correction underestimates the deviations from the Rutherford cross section The Rutherford cross section for recoils is given in the laboratory system by Z Z2 M M2 S 4 18 2M5E keV cos 9 oERP mb sr 2 07
87. cally by the uninstall program so there should be rarely if ever the necessity to use this parameter unregister Deletes all registry entries used by SIMNRA This is done automatically by the uninstall program so there should be rarely if ever the necessity to use this parameter Additionally SIMNRA accepts one optional command line parameter which is the name with full path of a NRA file This file is opened upon startup Use double quotes if the file name contains blanks Example simnra c test nra 3 20 2 OLE automation SIMNRA is an OLE 2 0 automation server which allows other applications to control SIMNRA This is useful for automatic processing of large numbers of spectra and allows to implement additional functions such as the calculation of spectra from laterally inhomogeneous samples 16 The available OLE objects and methods are described in Appendix A some sample programs can be found in section A 10 70 4 Physics uring the last decade several programs for the simulation of backscattering spectra have been developed The most common program is Doolittle s RUMP 17 18 However RUMP uses several approximations to save computing time The increase in computer power during the last years has made it possible to drop several of the approximations used by RUMP SIMNRA offers more freedom in the use of non Rutherford cross sections and nuclear reactions treats several topics such as straggling and
88. cally possible For heavy projectiles backscattered from light target nuclei two different solutions may be kinematically possible see Equation 4 4 The solution with the minus sign appears as Rutherford cross section low energy solution in the Reactions menu The buttons Rutherford and No Rutherford allow a quick selection of Rutherford Non Rutherford cross sections for all isotopes of an element The button Rutherford selects Rutherford cross sections for all isotopes and deselects all Non Rutherford and nuclear reactions cross sections The button No Rutherford deselects all Rutherford cross sections SIMNRA can handle non Rutherford cross sections for backscattering and recoil production and can use nuclear reactions cross sections SIMNRA is able to read two different file formats with cross section data 1 The R33 file format Cross sections for nuclear reactions and non Rutherford scattering are stored in the R33 file format originally proposed by I C Vickridge Many files with this extension have been taken from SigmaBase but several were added by the author Many of these files especially the ones containing nuclear reactions cross sections were digitised from the original publications by G Vizkelethy from Idaho State University No guarantee is provided for agreement with the original publication The references of the original publications are found in the file headers See subsection 3 16 1 and Appendix B for more details
89. centration lay el Integer Double Description Concentration of element number el in layer number lay The sum of concentra tions of all elements in a layer must be equal to 1 This is not checked by SIMNRA If ElementConcentration is changed it is the responsibility of the programmer to assure that the sum of the concentrations is equal to 1 Parameters lay Number of the layer with 1 lt lay NumberOfLayers el Number of the element with 1 lt el lt NumberOfElements lay ElementName Get Set Property ElementName lay el Integer WideString Description Name of element number el in layer number lay Returns XX if the element is unknown Attention Do not use ElementName to add new elements to the target The element should already be present in at least one layer If you add new elements they will have undefined cross sections Parameters lay Number of the layer with 1 X lay NumberOfLayers el Number of the element with 1 lt el lt NumberOfElements lay 179 A OLE automation reference HasLayerRoughness Get Set Property HasLayerRoughness lay Integer Boolean Description Specifies if the layer number lay is rough or not The FWHM of the roughness is specified by Target LayerRoughness If HasLayerRoughness is false the layer is treated as smooth and Target LayerRoughness is ignored Parameters lay Number of the layer with 1 X lay NumberOfLayers Related Properties and Me
90. cessary commands for reading and saving files and data printing spectra and terminating the program are located New This menu item resets the program to its starting values All calculated spectra target foil and setup definitions are deleted Open This menu item reads a saved calculation from disk SIMNRA can open files in the following formats nra file format SIMNRA version 6 and all earlier versions use the nra file format IDF and xnra file formats These are xml files according to the IBA data format IDF definition 1 This file format is very versatile for storing ion beam analysis IBA data and spectra and can be used for exchanging data between different IBA simulation programs SIMNRA 7 and higher use the new xnra file format This file format is based on the IBA data format IDF definition SIMNRA 6 06 can read xnra files created by SIMNRA 7 and higher It should be noted though that information can be lost if files created by SIMNRA 7 or higher are read with SIMNRA 6 06 Save This menu item saves all current parameters target and foil definitions experi mental and simulated data to disk See Save as for details Save stores data in nra file format Use Save as if you want to store the data in a different format Save as Like Save but you will be prompted for the name of the file and you can select in which format the data are saved Data can be saved in the following formats nra f
91. cher I Stensgaard and P Vase Nucl Instr Meth B 15 1986 459 142 215 Index A ADC OffSeU ees geen ne RE RR 18 Administrator privileges see Installation privileges Adobe Acrobat mirada RR Rees 3 57 Acrobat Reader 23 57 Andersen see Screening see Stopping power Appearance NEEN oe ade RI a ek E 56 Appearance progress window 56 Appearance toolbar ssss 56 Atomic data et EA EEN does roo era 73 B Biersack see Stopping power BOHP guter eb Rotes see Straggling Bozoian formula 80 Bragg s rule see Stopping power C Calculate menti SEENEN KEEN 48 52 Calculate Spectrum 48 Calculate Spectrum Fast 48 Gross Section 2 geg d Bee 48 Density asadas 48 Exit Angle Beta 48 Fit Spectrum dee pena ae 48 49 Keng NEEN yer Ze 48 Particles sT visir incor 48 SLOPPING as e emere rentrer E 48 Subtract Pile up 48 51 E EE 8 18 20 Canberra ooooooooccooncromnoo 8 18 20 Chi2 evaluation 0 0c cece eee ee 50 GRU as see Straggling Command line parameters 70 216 CONVENTIONS ec vere err ss Sener EEN es 2 Cornell geometry see Geometry Cross section calculation 48 Cross section data susuu 78 80 adding new data 0 62 integrated i seg eee t Aere ENS 77 Mott scattering oooococcccccccco o 80 non Rutherford
92. clear stopping s with the universal potential is given by In 1 1 1383 LE 4 36 n 2 e 0 01321 6021226 0 19593 605 4 36 for e lt 30 For e gt 305 is given by In e sn 4 37 2 The reduced energy e in Equation 4 36 and Equation 4 37 is calculated using the universal screening length ay which is 1 Z Tas 29 instead of the Firsov screening length ap o 2 gu which is used in Equation 4 35 The difference between Equation 4 34 and Equation 4 36 is only some percent The nuclear stopping component for heavy ions may be large and cannot be neglected 4 6 2 Ziegler Biersack stopping Hydrogen If Ziegler Biersack stopping is selected SIMNRA uses the electronic stopping power data by Ziegler Biersack and Littmark 5 for the stopping of incident protons deuterons and tritons in all elements The electronic stopping power S in eV 10 atoms cm for an incident hydrogen ion with energy mass E in keV amu is given by _ StowSHigh 4 38 f Stow S SHigh with Stow Cy E C4E 4 39 and Ub d SHigh EC ln E Cg 4 40 C Cg are fitting coefficients and partly tabulated in 35 They are stored in the file SCOEE95A for all elements Equation 4 38 to Equation 4 40 are valid in the energy range 10 keV amu 87 4 Physics E lt 10 MeV amu For energies in the range 10 100 MeV amu the electronic stopping power S is given by C S Co Cj0x Cy x 4 41 with x In E E Cy
93. convolution more precise and adds new possibilities such as dual scattering This section describes the physics involved in the simulation of a backscattering spectrum as performed by SIMNRA The target is subdivided into shallow sublayers Each simulated spectrum is made up of the superimposed contributions from each isotope of each sublayer of the sample target The thickness of each sublayer is chosen in such a way that the energy loss in each sublayer is about the stepwidth of the incoming particles When the incident particles penetrate a sublayer they loose energy due to electronic and nuclear energy loss and the beam energy is spread due to straggling The calculation of the energy loss is described in detail in section 4 5 and the calculation of straggling in section 4 8 SIMNRA calculates the energy of backscattered particles from the front and the backside of the sublayer and the energy of these particles when reaching the detector after passing to the target surface and traversing a foil in front of the detector see Figure 4 1 The contribution of each isotope in each sublayer will be referred to as a brick To account for energy straggling and the finite energy resolution of the detector the brick shown in Figure 4 1 is convoluted with a Gaussian function f E 0 with width 2 Ei 4 1 2 2 O Straggling Out Detector is the variance of the energy distribution of the outgoing particles due to energy 2 Detector P th
94. creasing depth the two effects compensate each other more and more until in large depths the path length differences become dominant and geometrical straggling increases 105 4 Physics 100 c E SSES GE E RBS Energy loss straggling 80b 0 ge Geometrical straggling BR A Detector resolution 60 40 Straggling contribution keV FWHM Depth 10 atoms cm Figure 4 11 Contributions of electronic energy loss straggling geometrical straggling and detector resolution to the total energy straggling at the sample surface for 2 6 MeV He incident on C 99D en Beam diameter 0 5 mm aperture width 0 5 mm distance sample detector aperture 100 mm detector resolution 15 keV FWHM Top RBS geometry with 0 165 a 0 B 15 for He backscattered from C Bottom ERDA geometry with 0 30 a 75 fj 75 for the deuterium recoils 106 4 Physics Figure 4 12 Examples of ion trajectories with one two and three scattering events 4 9 Multiple and plural scattering 4 9 1 Overview SIMNRA uses straight lines as trajectories for the ingoing and outgoing particles with one single scattering event connecting the trajectories of the particles see Figure 4 12 left This is only an approximation to physical reality because the particles on the ingoing and outgoing path suffer many small angle deflections with small scattering angles this has been called multiple scattering and addi
95. ction string separated by legal separators The order is m1 m2 m3 m4 for a reaction in which ml m2 gt m3 m4 The specification of which of the two initial and final masses are m1 and m3 respectively is given by the reaction string in which we always have m2 m1 m3 m4 so that m1 corresponds to the projectile and m3 to the light product At present there is no intention to cater for the few cases in which there are three or more products for example 11B p a 2a In principle the masses could be deduced directly from the reaction string however in the interests of simplicity it seems worthwhile adding them to the R33 file to avoid having to write a reaction string parser in R33 readers In the special case where the ScompositionS keyword is used the values there override any contained in the SMassesS entry R 1 1 1 1 lt n n n n gt 208 Composition Qvalue Distribution Theta Energy Sigfactors B The R33 cross section file format Note Four integers representing the atomic number of the four nuclei specified in the reaction string in the same order as the mass entries The Zs could also be deduced directly from the reaction string but see the comment in the Masses entry O Natural string 1 string gt Note This entry caters for elastic cross sections measured from targets that contain a mixture of isotopes from which the elastically particles are not resolved It consists of a list of isotopes and
96. ctor with only one scattering event with large scattering angle However some particles may suffer more than one scattering event with large scattering angle before they reach the detector see Figure 3 7 This is called plural scattering and results for example in the low background behind the low energy edge of high Z layers on top of low Z elements The deviations at low energies between simulated and measured spectra are also mainly due to plural scattering SIMNRA can calculate all trajectories with two scattering events If Dual Scattering is unchecked then only one scattering event is calculated This is the default If Dual Scat tering is checked additionally trajectories with two scattering events will be calculated Warning The calculation of dual scattering is a time consuming process If Dual Scattering is checked this will slow down the calculation of a spectrum by a factor of about 200 Note 1 If non Rutherford cross sections are selected for some elements then the selected non Rutherford cross sections will be used for the single scattering calculation The dual scattering calculation however is always performed with Rutherford cross sections Dual scattering requires cross sections at all possible scattering angles between amp 0 and 180 which are only available in the case of Rutherford cross sections This is reasonable in many cases because dual scattering is often dominated by heavy elements in the target where
97. curate and Fast models are compared in Figure 4 31 The Fast model cannot reproduce the pile up contribution which occurs without a pile up rejector because it assumes that two pulses always arrive simultaneously which is generally not the case However the Fast model is not too bad if a pile up rejector is used and the pulse rise time is larger than the pair resolution time of the pile up rejector In this case only pulses which arrive almost simultaneously are registered and two pulses with heights i and j add up to a sum pulse of height k amp i j as is assumed in the Fast model The fudge parameter Tf then is identical to the pair resolution time t Of the pile up rejector The comparison of the Accurate and Fast models can be summarized as follows 1 The Fast model can be applied if a pile up rejector is used and the pulse rise time T is larger than the pair resolution time 7 of the pile up rejector Because 75 X 0 5 us this means that T gt 1 us 2 The Accurate model has to be used if the measurement was done without a pile up rejector or if short pulses are used i e if the pulse rise time T lt 1 us The Accurate and Fast models are compared in Figure 4 32 to an experimental RBS spectrum Both models describe the experimental pile up quite well although the Accurate model gives a slightly better approximation to the experimental spectrum 134 4 Physics nee Accurate model PUR off Accurate model PUR on
98. d Setup Reads an experimental setup from file Note You can read any NRA file with Read Setup Only the setup information will be read any other information such as target composition experimental spectra etc which may be present in the NRA file will be ignored 14 3 Using SIMNRA 3 6 2 Setup Experiment More Options Detector type The information in this menu is only necessary if a special detector is used Special detectors are 1 thin solid state detectors A solid state detector is thin if particles are not fully stopped in the detector but loose only a fraction of their energy This can be the case for thin transmission detectors with thicknesses of 10 um or below or for nuclear reactions creating high energetic protons The penetration depth of 10 MeV protons in silicon is about 700 um so that these protons are only partly stopped in typical silicon detectors with thicknesses of the order of 100 um time of flight detectors electrostatic detectors These are often used in medium ion scattering MEIS SIMNRA is not intended to calculate MEIS spectra and the agreement to experimental spectra may be poor due to the large influence of plural scattering and neutralization effects Nevertheless SIMNRA can be used for a quick overview calculation how a spectrum may look like Detector type Select the type of detector Either solid state SSD time of flight TOF or electrostatic detector Solid
99. d a subsequent pulse with height j to a sum pulse of height k t is the time interval between the two pulses for modern Digital Signal Processors DSP s with the only difference that DSP s use digital filtering corresponding to trapezoidal pulse shaping instead of analog Gaussian shaping Identifying pulse height with channel number i e assuming linearity of the electronic system and no ADC offset then the probability P of a pulse of height i in channel i is given by nj P N where m i 1 with n the number of count in channel i m the total number of channels and N the total number of counts in the spectrum P is obtained from a simulated spectrum neglecting pile up effects or can be obtained from a low counting rate experiment in which the pile up probability is negligible The time lag between any two pulses is distributed according to the interval probability distribution which is derived from the Poisson probability distribution The probability P is the probability that a pulse of height i combines with a following pulse of height j to a pulse of height k Figure 4 26 In order to obtain a sum pulse of height k the second pulse j must arrive within a certain time interval t t dt The probability Du can be obtained as the product of the probabilities that 128 4 Physics 100000 10000 2 1000 c 2 o o 100 10 Without pile up With pile up 1 300 400 500 600 700 Channe
100. d they were not documented The fits were replaced by the original data files in REPLACE LST 47 3 9 3 Using SIMNRA Calculate menu In the Calculate menu all commands for calculating spectra scattering kinematics stopping powers and data fitting are located Additionally some helpful tools density conversions particles sr can be found here Calculate Spectrum Calculates the simulated spectrum Calculate Spectrum Fast Calculates a simulated spectrum but with a less accurate and faster integration algorithm Calculate Spectrum Fast can be up to 2 times faster than Calculate Spectrum but is generally less accurate Fit Spectrum Data fitting to experimental data See subsection 3 9 1 for details Kinematics Calculation of scattering kinematics Allows the calculation of the energies of backscattered particles recoils and nuclear reaction products Stopping Calculation of stopping powers for any projectile in any target element and of energy loss in the different layers Cross Section Calculation of Rutherford cross sections for backscattering and recoils Density Density conversions for elements only Mass density to atomic density and conversion from atoms cm to ug cm and nm Particles sr Calculation of particles sr from the collected charge and detector solid angle Exit Angle Beta Calculation of the exit angle 6 for IBM and Cornell geometry In IBM geometry incident beam exit beam
101. data are entered in different forms For example clicking Setup Experiment will show a window where experimental parameters are entered These forms can always remain open You can modify a parameter and perform a calculation by clicking Calculate Calculate spectrum or the button in the toolbar without the need to close the window thus minimizing the number of necessary mouse clicks Do not change parameters while a simulation is being calculated This may result in unpredictable behavior and may crash the program 3 2 Toolbar Often used commands are accessible through a toolbar see Figure 3 1 Clicking a button is identical to navigating to the corresponding command in the menu The toolbar can be switched off see section 3 12 3 3 Basic steps This section gives a quick overview about the basic steps necessary to calculate a backscattering spectrum Three steps must be performed before a backscattering spectrum can be calculated In a first step the experimental situation incident ions geometry has to be defined then the target must be created and in a third step the cross sections used for the calculation have to be chosen 1 Click Setup Experiment Here you choose the incident ions the ions energy define the scattering geometry see Figure 3 3 and you enter the energy calibration of the experiment 2 Click Target Target Here you create the target Each target consists of layers Each layer consists of differ
102. ded only as a discussion document the ascii format referred to as the R33 DSIR Report 33 format has become a de facto standard In the decade since this first proposal there have been spectacular advances in computing power and in software usability however the simplicity and cross platform compatibility of the ascii character set has ensured that the need for an ascii format remains Nuclear reaction cross section data for Nuclear Reaction analysis has been collected and archived on the Sigmabase websites google Sigmabase for about the last 7 years This data has largely been entered in the R33 format although there is a series of elastic cross sections that are expressed as the ratio to the corresponding Rutherford cross sections that have been entered in a format referred to as RTR ratio to Rutherford During this time the R33 format has been modified and added to firstly to take into account angular distributions which were not catered for in the first proposal and more recently to cater for elastic cross sections expressed as the ratio to Rutherford which it is useful to have for some elastic scattering programs It is thus timely to formally update the R33 format There exists also the large nuclear cross section data collections of the Nuclear Data Network the OECD NEA Nuclear data section the IAEA Nuclear data section and the Brookhaven 204 B The R33 cross section file format National Laboratory National Nuclear Data
103. dent and outgoing beams Intersection Intersection of this plane with the rough surface than the thickness d of the film We assume a rough substrate to consist of inclined line seg ments with local inclination angle y see Figure 4 15b and Figure 4 21 and the film thickness d is measured parallel to the local surface normal Such a rough surface is described by a distribution of local tilt angles p y The concept of a local tilt angle was already used by K stner et al for the calculation of the sputtering yield of rough surfaces by ion bombardment in the energy range 100 eV to several keV 78 In Kiistner s work the rough surface was treated as a fully 3 dimensional object which was necessary due to the 3 dimensional nature of the collision cascades created by keV ions In MeV ion beam analysis the trajectories of the incident and emerging ions can be approximated with good accuracy by straight lines and we have to consider only the intersection of the plane which is formed by the directions of the incident and emerging ions and the target surface see Figure 4 20 This is only a 2 dimensional line profile as the one shown in Figure 4 15b The tilt angle distribution is given by p y This distribution describes the frequency of occurence of a line segment inclined by y A rough surface without preferential orientation has a mean tilt angle 90 P vprlp dp O 4 79 90 The probability distribution p y of hitting a surface tilt
104. dent on 100 nm Au on top of Si scattering angle 165 Circles experimental data points dashed line simulation with one scattering event solid line simulation with two scattering events of the gold spectrum is better described The results with dual scattering are slightly lower than the experimental results This is due to trajectories with more than two scattering events which are not calculated 110 4 Physics 4 10 Surface roughness The quantitative application of ion beam analysis methods is usually restricted to laterally homogeneous and smooth films The experimentalist is often confronted with rough surfaces The effects of rough surfaces of thick targets on RBS were investigated in some detail by Edge and Bill 64 Knudson 65 Bird et al 66 and Hobbs et al 67 W est and Bochsler 68 and Yesil et al 69 70 attacked the problem by means of a Monte Carlo computer simulation taking into account correlation effects of the surface roughness and multiple surface crossings of the incident and emerging ions It turned out that effects of rough surfaces of thick targets occur only for grazing angles of the incident or emerging ions This is especially the case in ERDA on thick rough targets as was shown by Yesil et al 69 70 and Kitamura et al 71 Hydrogen depth profiling on rough surfaces by ERDA was studied experimentally by Behrisch et al 72 Astonishingly the effects of rough thin films were studied much mor
105. detector 13 15 92 energy resolution 92 free flight path 15 92 time resolution 15 92 top electrode Lsuuue 69 transmission detector 15 TYPO amp iisleniaas e e e EES ences 15 Detector geometry essesese 16 Doolittle see Energy loss evaluation Dual scattering 21 E Edit menu anidar dera ra 11 Copy Data eg occas roads 11 COPY Page meros cien 11 Energy of incident beam 12 Energy calibration see Detector Energy loss in layer jer we pU wee i REESE PI 48 Energy loss evaluation 82 83 Doolittle veinte 82 Runge Kutta i eee eere mmm 82 Energy spread of incident beam see Incident beam Exit angle 12 14 48 Experimental data see Spectrum data F File format e 7 Index 217 Id cereos ea ecu arava dota de ed oe z ROTA di O See 7 File MENU i2 s SNCT E RENE KAN AS 7 10 EXit ira tes UR gd Pati 10 NeW sakss vsu vex ed o T eU EE VE qos 7 OPER sessio ode p IDF EE 7 A 7 KALAT CETT 7 Ina eg 9 Read Spectrum Data 8 SE ret esters odina eg EN 8 A 8 jg 8 ISI acies e d respendpreU Ve PER RR 8 MGERD dei dee RE RE d 8 US ad ee 8 RUMP Read RBS bie 9 Read Sample Description File g Write Sample Description File 9 DAVE Lr canta weia s onere gw de px PR Z IDE EE 7 nir tor gg adsl 7 EH e
106. directory where SRIM 20nn exe is located nn is the year such as 2003 2008 etc You can use the small button to navigate graphically to that directory 3 Click Setup Calculation and go to the Parameter tab Select SRIM as Stopping power data SIMNRA uses SRIM to calculate stopping power tables These tables are stored in the SIMNRA STOP directory The file naming convention is SRIM2003 Z1 MI Z2 dat where Z1 and M1 are the nuclear charge and mass of the projectile and Z2 the nuclear charge of the target material Initially there are no SRIM stopping power files available but these files will be created successively whenever you are running a simulation 3 17 1 Trouble shooting If SIMNRA is not able to use SRIM stopping powers please read the error message carefully and act according to the following list Error message Error running SRIM module 1 Is SRIM 2003 or later installed on your computer See section 3 17 on how to install SRIM 2 Check the path to the SRIM program directory in the Options Preferences Directories form See section 3 17 for details 3 SIMNRA calls the program SRIM SR Module SRModule exe where SRIM is the SRIM program directory from the Options Preferences Directories form This program must exist and it must be located in the SR Module subdirectory note the blank between SR and Module Re install SRIM if this program does not exist Error message Error creating SRIM Module input fil
107. dit Copy Data the experimental and simulated spectra are copied in ASCII format to the windows clipboard They can be pasted into any spreadsheet program See section 3 5 for details 2 Via ASCII file With File Write Spectrum Data the experimental and simulated data are exported as columns into an ASCII file You can import this file into any plot program such as Excel Origin or Mathematica See section 3 4 for details 3 14 2 RUMP SIMNRA can read and write sample description files LCM and read RBS files RBS used by the RUMP program Sample description files contain the composition of the sample and the absorber foil These files can be read and written by File RUMP Read Sample Description File and File RUMP Write Sample Description File RUMP stores experimental parameters Type of incident particles incident energy scattering geometry etc and spectral data in binary files with extension RBS These files can be read by File RUMP Read RBS File SIMNRA can not write RBS files SIMNRA and RUMP use a different naming convention for the three angles incident angle scattering angle exit angle which define the geometry of an experiment The incident angle is called a in SIMNRA and O in RUMP The scattering angle is called 0 in SIMNRA while RUMP uses the supplement of the scattering angle 180 0 Direct backscattering is 0 180 in SIMNRA but 0 in RUMP The exit angle is called f in SIMNRA a
108. e 1 then the file type is determined automatically from the file extension Return Value Returns true if the file was opened successfully Related Properties and Methods App SaveAs 163 ReadSpectrumData Function ReadSpectrumData FileName WideString Format Integer Boolean Description Imports experimental data in different formats Parameters FileName The name of the spectrum data file including path 161 A OLE automation reference Format Format of the spectrum data file Allowed values for Format are 1 Data in ASCII file format 2 Data in Canberra s CAM file format 4 Data in RUMP s RBS file format 5 Data in user defined format Requires a used supplied dll See section 3 15 for more details Return Value Returns true if the file was imported successfully Related Properties and Methods App WriteSpectrumData 164 Restore Procedure Restore Description Restores the minimized application to its normal size Parameters None Return Value None Related Properties and Methods App Active 151 App BringToFront 156 App Minimize 160 SaveAs Function SaveAs FileName WideString FileType Integer 0 Boolean 162 Description Save a NRA file Parameters FileName FileType Return Value A OLE automation reference The name of the NRA file including path If the file already exists it will be overwritten Format of the file Allowed values for FileType are
109. e Cannot write to file xyz SIMNRA must have write access to the SRIM JNSR Module subdirectory and it must have write access to the file SRIM SR Module SR IN where SRIM is the SRIM program 66 3 Using SIMNRA directory from the Options Preferences Directories form This may be a problem for users with restricted permissions on Windows XB Vista or Windows 7 systems especially if SRIM is installed in the Programs branch This is a bug of the SRIM code which is not foreseen to be used with restricted permissions complain to the SRIM author Ask your administrator to give you write permission to the SRIM 20nn SR Module subdirectory Error message Error creating SRIM stopping power data file Cannot write to file xyz SIMNRA must have write access to the SIMNRA1 Stop directory where SIMNRA Stop is the stopping power data directory in Options Preferences Directories This may be a problem for users with restricted permissions on Windows XPVista or Windows 7 systems The SIMNRA setup program gives write permission for the SIMNRAI Stop directory to all registered users but somebody may have changed that later Ask your administrator to give you write permission to the SIMNRAN Stop directory Note Unrestricted write access to the SIMNRA Stop directory will not cause a security problem because this directory contains only data files Anything else Check the files SRIM2003 Z1 MI Z2 dat in the SIMNRA Stop directory
110. e SIMNRA W WINDE 4nd pnta e be EVE eie E ate 60 X X ray spectrum cee eee cece eee eee 52 Y KK EE see Straggling Index 220 ZBL potential Ziegler Asi 88 see Stopping power
111. e energy resolution of the detector The final contribution to the energy spectrum of each isotope in each sublayer is given by 2 H Straggling Out loss straggling and c oo S E So E f E Oo E dE 4 2 0 Here Su El is the energy spectrum before convolution and S E the spectrum after the con volution Note that the width of the Gaussian changes throughout the brick due to different straggling contributions TA backscattered particle may be a recoil or a product in a nuclear reaction as well 71 4 Physics Counts energy Energy Figure 4 1 Notation used for a single brick The Number of counts N in each channel i is given by integrating S E over the channel width from the minimum to the maximum energy of each channel Emax i N S E dE 4 3 Emin i Equation 4 2 and Equation 4 3 can be put together into a 2 dimensional integral which is computed by SIMNRA by means of a 2 dimensional Gauss Legendre integration The accuracy of the integration is about 10 The area Q of the brick in Figure 4 1 is calculated by using the integrated cross section see section 4 3 which is stable against fast varying structures in the cross section such as sharp resonances 72 4 Physics 4 1 Atomic data The masses of the elements and all isotopes used by SIMNRA have been taken from the recommended values of the 1995 update to the atomic mass evaluation 19 The abundances of the iso
112. e scarcely For RBS rough films on a smooth substrate were investigated by Shorin and Sosnin 73 and Metzner et al 74 75 Shorin and Sosnin 73 used a Monte Carlo computer simulation The Monte Carlo approach suffers from long computing times of the order of hours 70 rendering these codes impractical for evaluation of experimental spectra Moreover the Shorin Sosnin code treats only RBS with Rutherford cross sections neglecting non Rutherford scattering NRA and ERDA The theoretical approach of Metzner et al 74 75 allows to extract the thickness distribution of rough films from a measured spectrum However this approach is only valid for RBS with Rutherford cross sections a scattering angle of exactly 180 and constant stopping power thus severely limiting the practical applicability of this work The computer code RUMP 17 18 allows to fuzz the interface between two layers by roughening the top layer However this is intended only for small roughness amplitudes and the roughness distribution function is not documented Moreover all work done so far treats only the case of a rough film on a smooth substrate But in practice also the case of a film deposited on a rough substrate Figure 4 15 b is sometimes encountered This section describes the algorithms used for the description of rough surfaces and compares results of code calculations with experimental data The limitations of the used approximations are discussed 4 10 1 R
113. ead oooccccccccccncccc 13 P incident ion species 12 Parameters see Command line parameters number of particles 13 Particles st ind bec re ENTE 13 Installation vente Eege Aa 3 calculation sse 48 privileges eegen EES 3 Payment et Af ere id RER UR vii registration cessere sont d NNN na 3 Don p 94 system requirements esses 3 Pile D E Ne NEIE deg 18 26 127 134 accurate model 26 127 132 K calculation from experimental data 48 51 Kinematics 74 76 fast model 26 127 132 134 calculation mico 48 pile up rejector 20 52 132 elastic scattering 74 pair resolution time 20 52 132 backscattering 74 subtraction x see ot ree eed 48 51 icol M eet Seege RENES 74 Pile up rejector o oo ooomooo see Pile up nuclear reactions ooooommmmmmo 74 PIXE aia RR EE RESP E RETE E ERES 52 Plasma effect see Detector L Plot DECUyet voveo rt Ue ons see Screening paN RR 55 Layer A oed eben obs ER manipulation ooooooococncmo mo 29 Zoom OUt as 55 Layer roughness see Surface roughness Plot MENU ege EEN EN EEN AER 55 License agreement seesess ix Autoscaling cce 55 LIVE TEE 18 52 126 Delete Experimental Data EE Live time correction 18 126 Delete Simulated Data 55 Legend oti E
114. ead layer the dead layer is the insensitive region near the electrode The dead layer thickness can be obtained only experimentally by tilting the detector For light ions protons and He this should be sufficient to achieve a linear energy calibration But the nuclear energy loss and the plasma effect which are both important for heavy ions are not taken into account by this procedure An easier way to account for detector nonlinearities is to use a non linear energy calibration with a quadratic correction term of the form E keV A B x channel C x channel See subsection 3 6 1 for details 3 19 2 Energy calibration for different ion species As already shown in subsection 3 19 1 the pulse height defect depends on the particle species This requires an individual energy calibration for each ion species if different ion species are detected as is the case in NRA and ERDA measurements with incident heavy ions SIMNRA offers the possibility to use an individual nonlinear energy calibration for each detected species see subsection 3 6 1 for details 69 3 Using SIMNRA 3 20 Programming support 3 20 1 Command line parameters regserver Registers the OL automation server in the Windows Registry This is done automatically by the setup program so there should be rarely if ever the necessity to use this parameter unregserver Unregisters the OLE automation server from the Windows Registry This is done automati
115. ectra If checked individual spectra for each isotope in the target are calculated and plotted Default is unchecked Note The number of individual spectra is limited to 20 If the target contains many isotopes not all will be displayed Logfile If checked a file named SIMNRA LOG is created This file contains additional information about each step of the calculation and can be viewed with the program VIEWNRA The log file is written to the current directory if a nra file was opened or saved Otherwise it is written to the temporary directory defined by the operating system Default is unchecked Stepwidths tab Stepwidth incident ions Stepwidth of the incident ions used in the calculation See chapter 4 for details Automatic or Fixed can be selected If Automatic is selected the program will choose the stepwidth automatically This is usually the best choice for obtaining high accuracy and small computing times Automatic is the program default The automatically determined stepwidth is kept always below the resolution of the experiment Because the resolution in larger depths degrades due to energy loss straggling the program uses a small stepwidth near the surface and a larger stepwidth in 3 Using SIMNRA larger depths Fixed stepwidth The program uses a fixed stepwidth for the calculation If Fixed is selected the default for the stepwidth is 10 keV For incident heavy ions with energies in the range of several ten MeV this s
116. ed Properties and Methods TargetID 196 Stopping EnergyLossInLayer 196 StragglingInLayer Function StragglingInLayer Z1 Integer M1 Double E Double TargetID Integer lay Integer Double Description Energy loss straggling of an ion Z1 in a target or foil layer The layer is tra versed perpendicularly incident angle a and exit angle f are ignored The electronic energy loss straggling model is selected with Calc StragglingModel See Stopping EnergylossInLayer for a list of additional switches which influence the straggling calculation Parameters Zl Nuclear charge of the ion 199 A OLE automation reference M1 Mass of the ion amu E Incident energy keV TargetID Selects target or foil lay Number of the target or foil layer Return Value Returns the full width at half maximum FWHM of the energy loss straggling in the layer keV Related Properties and Methods TargetID 196 Stopping EnergylossInLayer 196 Calc StragglingModel 177 A 9 Error handling If SIMNRA is run as stand alone application i e not as OLE server it reports errors by showing message boxes with error messages or warnings and program execution is stopped until the OK button of the message box is pressed by the user This behaviour is reasonable for an interactive application but it is not wishful for an OLE server The server is controlled by another application or script and the display of a message box to a script is usel
117. ed by by an incident ion is given by B Y p y cos a v 4 80 with the incident angle a of the ion a is measured towards the surface normal of a non inclined surface The factor cos a y is due to the projection of the line segment into the 117 4 Physics incident beam Figure 4 21 Schematic representation of the incident angle a local inclination angle y and local incident angle plane perpendicular to the incident ion trajectory It is more likely to hit a segment which is perpendicular to the incident trajectory than an inclined segment and obviously it is impossible to hit a segment which is tilted parallel to the incident beam It is important to note that a profiler or a scanning tunneling microscope STM which samples the surface at a constant step width parallel to the surface measures the distribution p y rather than p y Large tilt angles are under represented and tilt angles of 90 cannot be measured at all RBS NRA and ERDA spectra of a smooth film on a rough substrate are approximated by a superposition of M spectra with different local incident angles where and local exit angles f The choice of f is discussed below M can be adjusted by the Number of angular steps in the Setup Calculation menu see subsection 3 6 3 The weight of each sub spectrum is determined according to the distribution function p y For each sub spectrum the substrate is treated to be smooth i e a spectrum f
118. ee parameters You can fit 1 Energy calibration energy channel and offset only quadratic term is not changed 2 Particles sr 3 Composition and thickness of a layer 4 Roughness of a layer 5SIMNRA uses 9 Nexp for Noxp gt 4 0 2 for N4 X 4 due to Poisson statistics exp 49 3 Using SIMNRA independently or all at once Check which parameters should be varied Only one layer at a time can be fitted Number of fit regions Number of different regions where y is calculated Up to 10 different regions may be used At least one region must be specified The regions should not overlap From To Lower and upper channel of each fit region e Chi2 evaluation Determines how y see Equation 3 6 is determined Channels 2 ey E uo Gen where No p 1 is the number of Ge counts in channel i and N 1 the number of simulated counts in channel i Integrals 2 8 ey Bm um cm where N i is the integrated number of mend counts in region i and Nsim 1 the number of integrated simulated counts in region i If Channels is selected then the shape of the spectrum is taken into account resulting in more accurate results in most cases If Integrals is selected then only count integrals in specified regions are taken into account This option should be selected if the agreement between experimental and simulated spectra is poor due to inaccurate energy calibration complicated peak
119. een assigned R C String 207 Masses Zeds B The R33 cross section file format Note the reaction string is written in a standard format that can be parsed without too much difficulty It conforms to the usual notation of target nucleus incident ion light product product nucleus Nuclei are specified by their chemical symbol preceded by A e g 28Si or 6Li The mass number is required Some common light species may also be represented by shorthand notation with lower case being required n neutron p proton d deuterium t triton a alpha particle h 3He x x ray g gamma The light product may correspond to a particular energy level of the product nucleus This is signaled by a postfix on the light product For example 160 d p1 170 is the d p reaction which leaves the residual 17 oxygen in the 1st excited state Some cross sections may be sums of several particle groups corresponding to different excited states of the compound or product nucleus Usually such a cross section would be used when the particle groups are not resolved by the detection method employed In this case the postfix lists the states concerned separated by plus signs E g 14N d p5 6 15N Some elastic cross sections correspond to targets having several isotopes In this case it is necessary to use the composition keyword R 1 1 1 1 lt 555r gt Note Four mass values in amu corresponding to the four nuclei specified in the rea
120. ent elements with some atomic concentration which does not change throughout the layer and each layer has a thickness Earlier versions of SIMNRA version 5 0 and earlier required these windows to be closed before a calculation could be performed 3 Using SIMNRA SIMNRA dit Setup Target Reactions Calculate Tool DER Bee E bu Energy keV 500 600 Options Help 1 000 950 900 850 Figure 3 1 SIMNRA toolbar marked in red If there is a foil in front of the detector then click Target Foil for the definition of a foil The default is no foil in front of the detector Like the target the foil can consist of different layers and the layers can have different compositions Click Reactions Here you have to choose which cross section data should be used for the simulation The default are Rutherford cross sections for all elements You can select non Rutherford cross sections instead and you can add nuclear reactions Now the spectrum can be calculated Click Calculate Calculate Spectrum for a simulation of the spectrum With Setup Calculation the parameters for the calculation can be altered The default values are normally sufficient and you should change these values only if you know what you are doing With File Read Spectrum Data a measured spectrum can be imported for comparison with the simulated one and for data fitting 3 Using SIMNRA 3 4 File menu In the File menu all ne
121. ental data Subtract pile up Subtracts the pile up contribution from the experimental data Warning Subtract pile up modifies irreversibly the experimental data 52 3 Using SIMNRA 3 10 Tools menu Several tools for spectrum evaluation are located in the Tools menu These tools appear as floating windows and are updated automatically if the spectrum is recalculated or a new spectrum is loaded from disk 3 10 1 Data Reader The data reader allows to read out the contents of a specific channel The data reader is displayed as a small black crosshair with white legend The data reader control window displays the channel the energy of this channel and the number of counts in the channel The data reader is moved by entering the channel number or by using the spin up spin down buttons in the control window The data reader is updated automatically if a spectrum is recalculated or if a new spectrum is loaded from disk 3 10 2 Integrate Spectrum The Integrate Spectrum tool allows to integrate a specific spectrum The integral of a spectrum is the sum of all counts between a lower and an upper channel including the boundary channels The integration boundaries are displayed as small black vertical lines in the plot The boundaries are moved by entering the channel numbers or by using the spin up spin down buttons in the control window The integral is updated automatically if a spectrum is recalculated or if a new spectrum is loaded fro
122. ential 34 The nuclear stopping S in eV 10 atoms cm for He ions with incident energy E in keV is given by 8 4627 ZM S 59 _ 4 33 i 2 3 42 3 M M Mz 23 z s is the reduced nuclear stopping and Z M are the nuclear charge and mass of the helium ion and Z5 M are the nuclear charge and mass of the target element The reduced nuclear stopping s has the simple form o os 0 9 Se 0 10718 693754 e is the reduced energy and is given by 32 53 M E e A A 4 35 1 2 ZZ My M z 23 Nuclear stopping is only important at incident energies E 100 keV at higher energies nuclear stopping becomes negligible 86 4 Physics Heavy ions The electronic stopping power of heavy ions in all elements is derived from the stopping power of protons using Brandt Kitagawa theory 5 35 The formalism is described in detail in ref 5 a short overview is given in 35 The screening length A eq 3 29 of ref 5 is multiplied by an empirical correction factor which has been digitised from fig 3 25 of ref 5 The correction factor for all elements is stored in the file LCORRHI DAT Note that the switch High energy stopping in the Setup Calculation menu has influence on the calculation of the stopping power for heavy ions with incident energies above 1 MeV amu Nuclear stopping for incident heavy ions is calculated with the universal potential from ref 5 The reduced nu
123. erford at both high and low energies for all projectile target pairs The low energy departures are caused by partial screening of the nuclear charges by the electron shells surrounding both nuclei 21 22 23 9 This screening is taken into account by a correction factor F o Fog For 0 gt 90 the correction factor by L Ecuyer et al 21 is widely used 0 04873 Z174 FLEcuyer 1 Ecu 4 16 Ecy is the energy in the center of mass system in keV Tabulated values of FLEcuyer can be found for example in 9 But note that L Ecuyer used the factor 0 049 instead of the correct 0 04873 24 in his original article The correction for backscattering angles 0 gt 90 at typical energies used in ion beam analysis usually is small For 1 MeV He ions on gold the correction is only about 3 596 The correction factor by LEcuyer Equation 4 16 is a first order correction and does not take into account the influence of the scattering angle 0 For 0 90 Equation 4 16 will underestimate the necessary correction to the Rutherford cross section A more accurate approximation is the angular and energy dependent correction factor by Andersen et al 23 2 1 Y Ca 2 2 V V Zei Ecm T EmA For M gt M there may exist two different solutions of the kinematic equation Equation 4 4 The cross section given by Equation 4 15 applies for the solution with the plus sign The cross section for the second solution of Equation 4 4 is o
124. ess Therefore if SIMNRA is running as server it handles errors in a different way Message boxes are suppressed and program execution continues even if an error is encountered The error is reported by an error flag as return value of the routine which produced it The text of the last error message can be retrieved with App LastMessage This behaviour can be changed by setting App ShowMessages true In this case error messages will be shown as message boxes and program execution is stopped until the OK button of the box is pressed SIMNRA is able to detect if it is running as stand alone application or as server and App ShowMessages is set to false automatically if invoked as server 200 A OLE automation reference The following code in Visual Basic Script shows the use of the error handling routines Create the application object Set App CreateObject Simnra App Wait 1000 ms May be necessary for the server to start WScript Sleep 1000 Open a NRA file Success App Open c temp test nra Some error reported by App Open Display last error message and exit If Not Success Then WScript Echo App LastMessage Exit End If Calculate a spectrum Success App CalculateSpectrum A 10 Programming examples Sample program in Borland Delphi showing the use of the OLE automation objects Var App Variant Result Boolean Begin Create the application object App CreateOLEObject Simnra App
125. f the exit angle f is given by 53 39 2 2 SCC I Lpcosa where d is the diameter of the incident beam w is the width of the detector aperture and Lp is the distance between the sample and the detector aperture see Figure 3 4 g and gy take into account the shapes of the beam and the detector aperture For circular detectors or circular beams with uniform current density g 0 59 g 0 68 for rectangular shapes as in the case of narrow slits 53 SIMNRA calculates geometrical straggling by calculating the energy at the surface of particles with exit angles Af 2 and f AB 2 and corresponding scattering angles 0 A0 2 and 0 A0 2 The spread of 0 is given by _ 00 SEI This equation can be solved only if the relation between D and 0 is known In IBM geometry see Figure 3 10 and section 3 9 the incident and outgoing trajectories are in the same plane with AO AB 4 72 180 a fPB 0 4 73 The spread in 0 is then simply given by A0 AP 4 74 Note the minus sign If 6 increases then 0 decreases and vice versa In Cornell geometry see Figure 3 10 and section 3 9 the relation between the angles a f and 0 is given by cos f cos 0 cosa 4 75 and the spread of 0 can be obtained from 90 1 sinf Of sin cosa 4 76 In general geometry the relation between the angles a f and 0 is undefined and 90 28 f cannot be determined Calculation of geometrical straggling is not possible for gene
126. fChannels 195 A OLE automation reference upChannel Upper channel with 0 lt upChannel NumberOfChannels Return Value Returns the sum of counts Related Properties and Methods spID 192 A 8 Simnra Stopping The Simnra Stopping object allows to calculate stopping powers energy losses and energy loss straggling in elements target and foil layers A 8 1 Input parameter The methods of Simnra Stopping require the input parameter TargetID which specifies if a layer is in the target or foil The possible values for TargetID are TargetID 1 Target 2 Foil Other values are not allowed A 8 2 Methods EnergylossInLayer Function EnergylossInLayer Z1 Integer M1 Double E Double TargetID Integer lay Integer Double Description 196 A OLE automation reference Energy loss of an ion Z1 in a target or foil layer The layer is traversed perpen dicularly incident angle a and exit angle f are ignored The stopping power model is selected with Calc ZBStopping page 178 and Calc HighEnergyStopping page 174 and may be additionally modified by a correction factor to the stopping power see section 3 7 The accuracy of the energy loss calculation is influenced by the settings of Calc AutoStepwidthOut page 172 and Calc dEOut page 173 Parameters Zl Nuclear charge of the ion MI Mass of the ion amu E Incident energy keV TargetID Selects target or foil lay Number of the target or f
127. fference increases and the distribution function is broadened If e lt er the energy difference decreases and the distribution function gets skewed The shape of the distribution remains unchanged a Gaussian distribution remains gaussian but the width of the Gaussian is changed according to Equation 4 544 To the non statistic broadening we have to add the statistical effects When the incident beam with initial energy Eg and initial beam width o c is the variance of the energy distribution the full width at half maximum FWHM is 2 421n20 2 355 0 penetrates a layer of matter with thickness Ax then the beam width o after penetrating the layer is given by i 2 o 2 o 0 4 57 ef and e are the stopping powers of the material at the entrance and exit of the layer and a is the energy loss straggling in the layer The first term in Equation 4 57 describes the non statistical broadening of the beam according to Equation 4 54 due to the energy dependence of the stopping power the second term adds the statistical effects The electronic energy loss straggling in Bohr approximation oe is given by 45 46 OF is keV 0 26 Z2 Z Ax 1018 atoms cm 4 58 In Chu s theory the Bohr straggling is modified by a correction factor H 50 46 Sc gt H E M Asia 4 59 Bohr s theory of electronic energy loss straggling is valid in the limit of high ion velocities In this case the electronic energy loss straggling is al
128. g power calculations SRIM 2003 or later must be installed See section 3 17 for details The Appearance tab Toolbar visible If checked a toolbar with speed buttons for opening and saving files calculating spectra etc is available See section 3 2 how to use the toolbar Program default is checked Progress window visible If checked a window displaying details about the progress of a calculation is shown during calculations This slows down the calculations Program default is checked 56 3 Using SIMNRA 3 13 Help menu User s Guide Opens the User s Guide in PDF format using Adobe Acrobat or Adobe Acrobat Reader Note Adobe Acrobat or Acrobat Reader are not part of SIMNRA Adobe Acrobat Reader can be obtained freely from the Adobe web site at www adobe com Home Page Opens the SIMNRA home page using your default web browser IBANDL Cross Sections Opens the Ion Beam Analysis Nuclear Data Library IBANDL home page using your default web browser IBANDL contains a large number of cross section data files for ion beam analysis and is hosted by the International Atomic Energy Agency IAEA About Shows the version number of the program Register Registration of the program 57 3 Using SIMNRA 3 14 Data exchange with other programs 3 14 1 Graphics programs Excel Origin SIMNRA allows to exchange data with graphics programs by two different methods 1 Via the clipboard With E
129. ge Z DaVe dS dencia EELER 74 Write Spectrum Data 8 o ins 2l iw ere E Rer 50 51 Fit Specttum EN EEN beeen eee ees 48 49 ACCULACY veste a ke 50 calculate fit error suusuue 50 fit erop de e e aio RET 50 51 max iterations ooooocococcoccmmo m 50 G Gamma distribution 112 Y LAY spectrum eee rrr rer hens 52 Genie 2000 3 8 Geometrical straggling 16 103 Geometry Cornell 12 48 49 104 General 3 vcasteeet dates sees 104 IBM vecinas 12 48 49 104 118 H Help mem EELER EE Se sre RE EN 57 Index ADOUE esse terre REINO eU 57 Nuclear stopping esess 86 89 Home Page osx b e rines 57 krypton carbon potential 86 IBANDL Cross Sections 57 universal potential 87 Register i ceres e a EEN 57 ZBL potential sesese 88 User s Guide ue ere trenes 57 O I OLE automation 70 145 203 IBA data furnace see e eee eee eee 60 data types cis ec eeh AEN edens 151 BAND estate remet eg ea 62 methods caricia aaa 145 IBM geometry oooooooccom m see Geometry A e POOR ee en 145 Incident angle Lsuu 12 14 Options menu ococcccccccccnccccccncr o 56 Incident beam 13 Create Reaction List 56 charge state cece eee eee eee 13 Preferences i ssec wes SE ven deve 56 enetey ENEE 12 energy spr
130. geometries a and 0 must be defined first with Setup Alpha and Setup Theta Parameters Geometry IBM or Cornell geometry Possible values for Geometry are 0 IBM geometry 1 Cornell geometry Any other value for Geometry is ignored Return Value Returns the exit angle fp Related Properties and Methods Setup Beta 165 171 A OLE automation reference A 4 Simnra Calc The Simnra Calc object represents the parameters of the calculation A 4 1 Properties AutoStepwidthIn Get Set Property AutoStepwidthIn Boolean Description Specifies if automatic step width control for incident ions is used Related Properties and Methods Calc AutoStepwidthOut 172 AutoStepwidthOut Get Set Property AutoStepwidthOut Boolean Description Specifies if automatic step width control for outgoing ions is used Related Properties and Methods Calc AutoStepwidthIn 172 CreateSpectrum Get Set Property CreateSpectrum Boolean Description Specifies if a spectrum is calculated or not This parameter is always True and should not be changed 172 A OLE automation reference dEin Get Set Property dEin Double Description Stepwidth incident ions keV Related Properties and Methods Calc dEout 173 dEout Get Set Property dEout Double Description Stepwidth outgoing ions keV Related Properties and Methods Calc dEin 173 DualScattering Get Set Property DualScattering Boolean
131. gles Enter the full width at half maximum FWHM of the angle distribution in deg 3 7 3 Target Foil In this menu a foil in front of the detector can be created Like the target a foil can consist of multiple layers with different compositions See the previous section for details If the foil consists of multiple layers then backscattered particles first will penetrate layer n then layer n 1 etc layer 1 is directly in front of the detector see Figure 3 8 The default is no foil in front of the detector Some common materials used as stopper foils are already stored in the LAYERS directory The materials and files are listed in Table 3 3 These files can be imported in the Target menu with File Read layer 32 3 Using SIMNRA Filename Material Common name INCON600 LAY Inconel 600 INCON625 LAY Inconel 625 SS14301 LAY Stainless steel 1 4301 AISI 304 US SS14541 LAY Stainless steel 1 4541 V2A S814571 LAY Stainless steel 1 4571 V4A SS316 LAY Stainless steel 316 US MYLAR LAY Polyethylenterephthalat Mylar Hostaphan Table 3 3 Predefined materials for stopper foils stored in the LAYERS directory 33 3 Using SIMNRA 3 8 Reactions menu In the Reactions menu the cross sections used for calculation of the simulated spectrum are chosen Rutherford cross sections for backscattering of projectiles and creation of recoils are available for all ion target combinations if kinemati
132. gling 52 This justifies to neglect nuclear straggling for all ion species 4 8 4 Energy loss straggling in compounds For compounds a simple additivity rule for energy loss straggling is used 46 The straggling in a compound consisting of elements i with atomic concentration c is calculated with o cio 4 70 i 2 r with c7 being the straggling in each element 4 8 5 Geometrical straggling The finite size of the incident beam and the width of the detector aperture result in a spread Af of the exit angle f for outgoing particles This angular spread leads to different energies of the particles at the target surface due to 1 a spread A0 of the scattering angle O and therefore a spread of the transferred energy in the scattering process 5SIMNRA versions before 4 70 used a quadratic addition of the nuclear and electronic energy loss straggling contributions i e o o 92 with 0 the variance of the nuclear straggling and c the variance of the electronic straggling Due to the different shape of the two distributions this is incorrect and results in an overestimation of the total straggling This error is negligible for light ions H Het but may play a role for heavy ions 103 4 Physics 2 different path lengths of the outgoing particles in the material These two contributions to geometrical straggling are not independent of each other and have to be considered simultaneously The spread Af o
133. gy of backscattered ions at the target surface Middle Electronic energy loss straggling at the target surface Bottom Error of the straggling calculation and error estimate based on Equation 4 67 102 4 Physics 4 8 3 Nuclear energy loss straggling Fluctuations in the number of nuclear collisions lead to nuclear energy loss straggling which can be described by Bohr s theory of nuclear straggling The variance c in Bohr s approximation is given by M 2 o keV 0 26 Z z Ax 1018 atoms cm 4 69 Nuclear energy loss straggling is small compared to electronic energy loss straggling for light ions protons or helium ions and can be neglected Nuclear straggling becomes more important for heavy ions and variance of nuclear straggling may exceed electronic energy loss straggling see Equation 4 58 and Equation 4 69 However it has been shown experimentally for 60 MeV 5Ni ions in different target materials that the width of the total straggling distribution is only somewhat larger than electronic energy loss straggling alone 52 The nuclear straggling energy distribution is broad with a long tail towards low energies which cannot be described by a Gaussian distribution This tail leads to the large variance of nuclear straggling However the tail contains only a small fraction of all particles and the width of the total energy distribution electronic plus nuclear straggling is still dominated by electronic energy loss strag
134. hown in Figure 4 6 The Z oscillations are clearly visible The Chu correction is mainly necessary for high Z and low energies For high energies H approaches 1 and becomes independent of Z and energy For E M values in the range 100 1000 keV amu the data have been taken from ref 46 data for lower and higher E M values are based on an extrapolation performed in ref 39 Tabulated values for H are stored in the file CHU CORR DAT For not tabulated values SIMNRA uses linear interpolation Charge state fluctuations of the ions result in an additional straggling contribution which was taken into account empirically by Yang et al 51 In Yang s theory the total straggling is expressed by 2 2 2 by Oo Ao Yang 2 Chu 7 41 22 04 4 60 Bohr Bohr O Bohr 96 4 Physics where y Zi Z5 v is the effective charge factor for ions in matter v the ion velocity and Ao is the additional straggling due to correlation effects For hydrogen ions in matter Yang always assumes a charge state of one i e y 1 A fit to about 600 different empirical data points with a deformed resonant function gave Ao BI ien SCH H E E B T l with T B3 1 exp B E 4 62 where E is the energy in MeV amu and B B are fitted constants Helium and heavier ions are not always fully stripped but the charge state is a constantly changing parameter fluctuating along the trajectory The effective charge state y Z Z5 v w
135. hr straggling is broader than the experimental data The Chu straggling fits the measured curve relatively well except of the multiple scattering contribution The straggling of outgoing particles is calculated with Equation 4 57 as well Outgoing particles always start with an energy distribution with variance GE which is given by Con KO 4 66 with K the kinematic factor and Ga the variance of the energy distribution of the incident beam Accuracy of electronic energy loss straggling calculations SIMNRA uses Equation 4 57 for the calculation of straggling However Equation 4 57 is only correct for infinitesimal thin layers i e if Ax see Equation 4 58 is sufficiently small It gets more and more inaccurate for thicker layers because the straggling propagation for the second term in Equation 4 57 is neglected The error Ao for o see Equation 4 57 can be estimated to be 2 We ifl y Ame d 2 OS if 1 ef e gt 0 03 TT 0 03 GAx else G depends on theory For Bohr straggling it is given by Equation 4 58 and for Chu and Yang straggling by Equation 4 59 and Equation 4 60 respectively 0 03 is based on extensive tests of Equation 4 67 Using only the upper half of the equation results in unrealistically small error estimates and too large step widths around the stopping power maximum where e e on both sides of the maximum The step width Ax for electronic energy loss straggling calculations is selected in such a
136. ibution of the CFC surface Solid line Experimental data Dashed line Lorentz distribution times cosine of the tilt angle Dotted line Gaussian distribution times cosine of the tilt angle 121 4 Physics 1000 1200 1400 1600 1800 Energy keV Figure 4 23 Calculated energy spectra for 2 MeV He backscattered from a gold layer with thickness 1 x 101 Au atoms cm on a rough substrate with different roughnesses The roughness is described by a Lorentz distribution of tilt angles with FWHM w w oo is an equipartition of tilt angles Incident angle a 0 scattering angle 165 122 4 Physics e Experimental Smooth plural scattering 400 Rough plural scattering 300 200 Counts 400 600 800 Channel Figure 4 24 2 5 MeV protons backscattered from 3 5 um W on a rough carbon substrate scattering angle 165 Dots Experimental data Dotted line Calculated spectrum for a smooth W layer 3 6 um on a smooth C substrate including plural scattering Dashed line Calculated spectrum for a rough W layer 3 5 um O 0 30 um on a rough substrate FWHM 20 Solid line As dashed line but including plural scattering Figure 4 22 is best described by a FWHM of 26 6 while the best fit to the measured spectrum yields a FWHM of about 20 It is assumed that inaccuracies in the measurement of the tilt angle distribution at high inclinations due to the apex angle of the profiler tip and the constant step wid
137. ich the low energy edge has decreased to its half height is no good measure for the film thickness It depends on the roughness of the substrate The high energy edge and the plateau are only slightly affected by substrate roughness and decrease only little at large roughnesses due to shadowing The backscattered particles do not reach the detector any more because the exit angle f points inside the layer For w oo the local tilt angles are equipartitioned and the corresponding spectrum represents the case of maximum roughness A measured spectrum for 2 5 MeV protons backscattered from a tungsten layer on top of a rough carbon substrate is shown in Figure 4 24 The non Rutherford elastic scattering data from 80 were used for the C p p C cross section The substrate is the same CFC material which surface is shown in Figure 4 22 The mean W layer thickness was about 3 5 um while the standard deviation of the substrate roughness was about 8 2 um i e the substrate roughness was considerably larger than the thickness of the W layer The dotted line in Figure 4 24 is the calculated spectrum for a smooth W layer on a smooth carbon substrate Plural scattering in the W layer was included in dual scattering approximation see subsection 4 9 3 Plural scattering results for example in the small background visible between the carbon and tungsten signals in channels 500 650 This spectrum has only minor resemblance with the experimental curve and requires
138. ilable Create Reaction List will create this file You have to recreate the reaction list if you add or delete cross section data files see section 3 16 Note In some cases files are not readable by SIMNRA due to format errors These files will be ignored The program displays a list of all ignored files Preferences Allows to set global program preferences These preferences are stored permanently The Print tab White background for print If checked then the grey background of the graph is changed to white in the printout Show Print What dialog If checked then a dialog asking what to print exper imental conditions graph is displayed If unchecked this dialog is omitted and everything is printed The Spectrum Data tab Determines which menu entries are visible in the File Read Spectrum Data menu The Saving tab Create BACKURNRA when saving If checked the old NRA file is saved to a file named BACKUPNRA each time File Save or File Save As is used In the case of erraneous overwriting of a file you can recover the old data from this file In each directory only one BACKUBNRA can exist The Directories tab Determines in which directories the program looks for atomic cross section and stopping power data This is mainly useful if the data are stored on a network drive and are accessed simultaneously from different computers SRIM program directory Base directory of the SRIM program for stoppin
139. ile format SIMNRA version 6 and all earlier versions use the nra file format and it is recommended to save all files in this format xnra file format The xnra file format is used by SIMNRA 7 and higher This file format is based on the IBA data format IDF definition IBA data format These are xml files according to the IBA data format IDF definition 1 This file format is very versatile for storing ion beam analysis IBA data and spectra and can be used for exchanging data between different IBA simulation programs The default file format is nra Depending on the settings in Options Preferences Saving see section 3 12 the old NRA file can be saved to a file named BACKUBNRA In the case of erraneous overwriting of a file you can recover the old data from this file 3 Using SIMNRA Read Spectrum Data This menu item allows the import of experimental data The availability of menu items depends on the settings in Options Preferences Read Spectrum Data ASCII Allows the import of experimental data in ASCII format The data file format must be as follows The file may contain an arbitrary number of comment lines at the beginning of the file A comment line is a line that contains any non numeric character These lines will be ignored The first line that contains only numeric characters will be treated as the first line of data Each data line must consist of two columns In the first column the channel number must
140. ine containing the string QValue The Q value is the energy released in the nuclear reaction in keV Q 0 0 for elastic scattering Up to 5 different Q values are allowed for example for multiple particle groups which are not resolved SIMNRA will use the mean value of all non zero Q values A line containing the string Theta Theta should be given in degrees The value of theta is not used by SIMNRA but this line must be present and contain a value Optionally a line containing the string Units may be present Valid values are mb for differential cross sections rot for total cross sections and rr for ratio to Rutherford Differential cross sections have to be in mbarn sr and total cross sections in mbarn If the Units line is omitted SIMNRA will assume mb i e differential cross sections The value tot indicates that the cross section is integrated over all angles Thus if rot is used the value of theta has no meaning Nevertheless a valid real number has to be given for theta Aline containing either the string Nvalues or Data The value of Nvalues is ignored SIMNRA assumes that the data will start after this line The data are organised in 4 columns The first column is the energy in keV the second column is the energy error in keV ignored by SIMNRA the third column is the cross section in the laboratory frame and the fourth column is the cross section error ignored 64 3
141. ing power data for the stopping of light and heavy ions in all elements The differences between the data sets are typically lt 5 but may be larger in some cases especially for ions other than H or He See 30 31 32 for a discussion of the accuracy of stopping powers An up to date compilation of stopping power data can be found in 33 4 6 1 Andersen Ziegler stopping Hydrogen If Andersen Ziegler stopping is selected SIMNRA uses the electronic stopping power data by Andersen and Ziegler 3 for the stopping of incident protons deuterons and tritons in all elements The electronic stopping power S in eV 10 atoms cm for an incident hydrogen ion with energy mass E in keV amu is given by CE 4 26 S SLow SHigh l with Slow A E 4 27 and A3 A4 SHigh E In 1 E T ASE 4 28 A As are fitting coefficients and tabulated in 3 They are stored in the file STOPH DAT Equation 4 26 to Equation 4 28 are valid for 10 keV lt E lt 1 MeV For energies in the range 1 MeV 100 MeV the electronic stopping power S is given by Ag A B i S p2 In Le Be 2 Ans In E 4 29 Ag Ar are tabulated in 3 6 v c with v the ion velocity and c the speed of light Equation 4 29 is used only if the switch High energy stopping in the Setup Calculation menu is checked If unchecked the program will use Equation 4 26 to Equation 4 28 at all energies The program default is checked The difference betwee
142. ion species may be supplied If no 12 3 Using SIMNRA individual energy calibration is defined the major energy calibration entered in the Calibration fields of the Setup Experiment form see above is used Attention The energy scale which is plotted at the top of the plot is obtained with the major energy calibration from the Calibration fields of the Setup Experiment form The energy scale is not valid for particles with individual energy calibrations Particles sr Number of incident particles times the solid angle of the detector Solid angle in steradians The number of incident particles is obtained from the collected charge and the charge state Calculate Particles sr can be used for the calculation Detector Resolution Energy resolution of the detector in keV The energy resolution is measured as full width at half maximum FWHM This energy resolution is used for all ion species if no specific resolution for that ion is supplied see below Detector Resolution is used only for solid state detectors See section 3 6 2 if you are using a different type of detector such as a time of flight detector SIMNRA can use different detector energy resolutions for different ion species By pressing the button detector energy resolutions for each ion species may be entered If no energy resolution for an ion species is supplied the default resolution see above is used Note 1 Detector Resolution is only available if Detec
143. ipboard is as follows The data are organised in three columns The first column contains the channel number the second column contains the experimental data and the third column contains the simulated data The columns are separated with tabs Spectra of individual elements or isotopes are not copied to the clipboard Use File Write Spectrum Data to export spectra of individual elements or isotopes to a file Copy Page Copies the visible graphics to the clipboard in enhanced metafile format You can paste the graphics into any word processing program such as Microsoft Word 11 3 Using SIMNRA 3 6 Setup menu 3 6 1 Setup Experiment In the Setup Experiment menu the global parameters of the backscattering experiment are defined Less often used parameters necessary for geometrical straggling and pile up calculations etc can be found in the Setup Experiment More Options menu Incident ion Selects the incident ions For incident protons H D T He or He ions the ions are selected by clicking the appropriate radio button For incident heavy ions select Other and enter the ions name in Other ion Element for example Si Cl I Lowercase and uppercase letters in the ions name are treated similar you can enter silicon as Si si SI or sI The ions mass is selected from the drop down box Energy Energy of the incident ions in keV Geometry Geometry of the experiment Incident angle a exit angle f
144. iseTime Rise time of the amplified pulse from zero to its maximum value us SetBeta Sets the exit angle D as function of incident angle a and scattering angle 0 for IBM and Cornell geometries Theta Scattering angle deg 147 A OLE automation reference Simnra Calc AutoStepwidthIn Specifies if automatic step width control for incident ions is used AutoStepwidthOut Specifies if automatic step width control for outgoing ions is used CreateSpectrum Specifies if a spectrum is calculated dEin Stepwidth incident ions keV dEout Stepwidth outgoing ions keV DualScattering Specifies if dual scattering is calculated ElementSpectra Specifies if individual spectra for each element in the target are calculated EMin Cutoff energy keV HighEnergyStopping Selects high energy stopping Andersen Ziegler only Isotopes Specifies if isotopes are taken into account IsotopeSpectra Specifies if individual spectra for each isotope in the target are calculated LogFile Specifies if a log file SIMNRA LOG is created MultipleScattering Specifies if multiple scattering is calculated NumberOfAngleVariations Number of angle steps in the calculation of rough substrates NumberOfDVariations Number of thickness steps in the calculation of rough layers PUModel Selects the pile up model ScreeningModel Selects the electronic screening model to the Rutherford cross
145. istribution has to be used as tilt angle distribution A line profile of the surface of a carbon fibre composite CFC material manufactured by Dunlop is shown in Figure 4 22 top Due to its high thermal conductivity this material is used for high heat flux components in the tokamak experiment JET The standard deviation of the surface roughness is about o 8 2 um 119 4 Physics A histogram of the tilt angle distribution p y obtained with a profiler from several line scans in different sample directions is shown in Figure 4 22 bottom Tilt angles larger than about 60 are not observed due to the apex angle of the profiler tip The tilt angle distribution is fairly well described by a Lorentz distribution for the tilt angles p p dashed line while a Gaussian distribution underestimates strongly the wings of the distribution dotted line The full width at half maximum FWHM of the Lorentz distribution is 26 6 Calculated backscattering spectra for incident He ions backscattered from a gold layer with thickness 1 x 101 atoms cm at a scattering angle of 165 are shown in Figure 4 23 for a smooth and rough substrates The rough substrates are described by a Lorentz distribution of tilt angles with different FWHM w On a rough substrate the low energy edge gets a tail which increases with increasing roughness This tail extends to energies close to zero With increasing roughness the Au peak also gets broader and the energy E at wh
146. it parameters in the Simnra Fit see page 186 object first before the fit can be performed with FitSpectrum Parameters None Return Value Returns true if the fit succeeded Hide Procedure Hide Description Hides SIMNRA The program is still running but not visible Parameters None Return Value None Related Properties and Methods App Minimize 160 App Show 163 Maximize Procedure Maximize 159 A OLE automation reference Description Maximizes SIMNRA to fill the whole screen SIMNRA must be visible i e not minimized or hidden otherwise Maximize has no effect Parameters None Return Value None Related Properties and Methods App Minimize 160 Minimize Procedure Minimize Description Minimizes SIMNRA to the Windows task bar Parameters None Return Value None Related Properties and Methods App Maximize 160 App Restore 162 App Active 151 App BringToFront 156 Open 160 A OLE automation reference Function Open FileName WideString FileType Integer 1 Boolean Description Opens a NRA file Parameters FileName The name of the NRA file including path FileType Format of the file Allowed values for FileType are 1 Unknown file format 0 NRA file format 1 IBA data format IDF file 2 XNRA file format See section 3 4 for more details about the file formats FileType is optional and can be omitted If FileType is omitted or if FileTyp
147. ixed can be selected If automatic is selected the program will choose the stepwidth automatically This is usually the best choice for obtaining high accuracy and small computing times Automatic is the program default The automatically determined stepwidth is large at high energies where the stopping power shows only small variations to decrease computing time The step width is decreased near the stopping power maximum and at low energies where the stopping power varies strongly to increase accuracy Fixed stepwidth The program uses a fixed stepwidth for the calculation of outgoing particles The stepwidth will remain constant at all energies and for all outgoing particles If Fixed is selected the default for the stepwidth is 200 keV For incident heavy ions with energies in the range of several ten MeV this stepwidth can be increased If a small fixed stepwidth is used this may increase the accuracy of the calculation but will slow down the calculation A very small fixed stepwidth may be even more accurate than Automatic stepwidth control should not be used together with narrow resonances in the cross section with SIMNRA 5 01 and earlier SIMNRA 5 01 and earlier require a sufficiently small Fixed stepwidth if used with narrow resonances see section 4 3 25 3 Using SIMNRA automatic stepwidth control In contrast a large fixed stepwidth decreases the accuracy of the calculation but will speed up the calculation There is no eas
148. l Figure 4 27 Effect of pile up on a single peak The inset shows the individual and the sum pulses which give the pile up spectrum 129 4 Physics 1 There is no pulse between time zero when the initial pulse occured and time t Ree 2 There is one pulse between time t and time t dt P adt 3 There are zero pulses between time t dt and the end of the first pulse T p e UT 0 For details see 82 The differential P is the product of these probabilities AP jx ae w dt A pulse height analyzer is only capable to analyze pulses into discrete channels multi channel analyzer The Pjj is obtained by integrating the differential probability over the time period that will give a pulse of size k This time interval is from t4 i j k to to i j k 1 so that P Sa 4 87 ijk t J dt ae l t t 4 88 ae 9Tw Atijk 4 89 The probability P is proportional to the time increment At between the two pulses Unfortunately the time increment At can be calculated analytically only for very simple pulse shapes Wielopolski and Gardner 82 approximated the true pulse shapes by parabolic pulses see Figure 4 28 and Figure 4 29 In that approximation At is obtained from E EEN ei an i Al i 1 2 Letzte 4 90 where T is the pulse rise time i e the time to reach the maximum value see Figure 3 5 and l is whichever is largest of i and j For parabolic pulses we can use
149. lable for scientific purposes SIMNRA was developed at the Max Planck Institut f r Plasmaphysik Garching Germany viii Product license agreement The product license agreement can be found in the file LICENSE TXT The product license agreement is part of SIMNRA Version history Program changes from version 5 0 to 6 0 are described in the file Changes 6 0 txt Changes between earlier versions are described in Changes 5 0 txt and Changes 4 4 txt 1 Overview his report describes the use of the program SIMNRA and the physical concepts implemented T therein SIMNRA is a Microsoft Windows program for the simulation of back or forward scattering spectra for ion beam analysis with MeV ions SIMNRA is mainly intended for the simulation of spectra with non Rutherford backscattering cross sections nuclear reactions and elastic recoil detection analysis ERDA About 300 different non Rutherford and nuclear reaction cross sections for incident protons deuterons 3He and He ions are included SIMNRA can calculate spectra for any ion target combination including incident heavy ions and any geometry including transmission geometry Arbitrary multi layered foils in front of the detector can be used Several different stopping power data sets are available Energy loss straggling is calculated including the corrections by Chu and Yang to Bohr s theory Energy loss straggling propagation in thick layers is considered correctly Additionally the effect
150. lay Integer Boolean Description Adds an element to layer number lay The element has no name and zero concen tration After adding the elements properties have to be set with ElementName and ElementConcentration Attention Do not use AddElement to add new elements to the target See ElementName for details Parameters lay Number of the layer with 1 X lay NumberOfLayers Return Value Returns true if the element was added successfully Related Properties and Methods Target AddLayer 183 Target ElementConcentration 179 Target ElementName 179 AddLayer Function AddLayer Boolean Description Adds a new layer The layer is the last layer in the stack has zero thickness and contains no elements After adding a layer at least one element has to be added with AddElement and layer properties like thickness roughness etc have to be set 183 A OLE automation reference Parameters None Return Value Returns true if the layer was added successfully Related Properties and Methods Target AddElement 183 Target InsertLayer 185 DeleteElement Function DeleteElement lay el Integer Boolean Description Deletes element number el in layer number lay Parameters lay Number of the layer with 1 X lay NumberOfLayers el Number of the element with 1 lt el lt NumberOfElements lay Return Value Returns true if the element was deleted successfully Related Properties and Methods
151. lculation are shown in Figure 4 4 for Ziegler Biersack stopping The Ziegler Biersack stopping as used by SIMNRA see subsection 4 6 2 especially section 4 6 2 is smooth with continuous second derivative due to spline interpolation of the input data and the energy loss calculation according to Doolittle s formula Equation 4 25 results in a maximum error of about 50 eV Runge Kutta with identical step width is more accurate with a maximum error below 1 eV The same calculation but with SRIM 2003 stopping powers is shown in Figure 4 5 The SRIM 2003 stopping power has no continuous derivative and Doolittle s method results in serious deviations The Runge Kutta method still gives accurate results with a maximum error of about 20 eV 83 4 Physics 2000 T T T Precise Step width 100 keV Runge Kutta Doolittle 1500 1000 4 Energy keV 500 4 8000 E 6000 E 4000 L J 2000 4 Energy error eV E 2000 f 1 f 0 0 0 5 1 0 1 5 2 0 Depth 10 atoms cm Figure 4 5 Slowing down of 2 MeV He in Au with SRIM 2003 stopping calculated with different numerical methods Top He energy as a function of depth Bottom Error of the calculated energy The Precise result was obtained with a Runge Kutta method using a step width of 1 keV 84 4 Physics 4 6 Stopping power data SIMNRA offers the possibility to use several different sets of electronic stopp
152. low energy Au edge is due to plural scattering this means the backscattered particles have suffered more than one scattering event with large scattering angle 57 58 59 which was not simulated for this example The deviation between experiment and simulation at low energies in the Si spectrum is due to the same reason Figure 5 2 compares simulated spectra with single and dual scattering for 500 keV He ions incident on a 100 nm gold layer on top of silicon with experimental data At this low energy plural scattering is important With the inclusion of dual scattering the experimental results are much better approximated Dual scattering gives the background between the low energy edge of Au and the Si edge and the steeper increase of the gold spectrum is better described The results with dual scattering are slightly lower than the experimental results This is due to trajectories with more than two scattering events which are not calculated 137 Counts 5 Examples Energy keV 200 400 600 800 1000 e experimental 6000 simulated 4000 2000 A 0 KE 100 200 300 400 500 600 700 800 Channel Figure 5 1 1000 keV He incident on Au on top of silicon 9 165 138 5 Examples Energy keV 100 200 300 400 ide 14000 e Experimental Dual scattering 12000 Single scattering 10000 D 8000 c 9 amp 6000 4000 2000 ES 200 300 Channel Figure 5 2 500 keV He ions incident on 100 nm Au on top of
153. m disk 3 10 3 Nearest Elements The Nearest Elements tool marks the channels in which backscattered particles from specific elements or recoiled particles would appear This allows easy identification of unknown peaks in the spectrum The tool shows the three elements which are closest to the cursor The cursor is displayed as a black vertical line and is moved by entering the channel number or by using the spin up spin down buttons in the control window The Nearest Elements tool uses the surface approximation i e stopping power effects are neglected The marked channels are only valid for elements at the surface Limitations 1 Stopping in a foil in front of the detector is neglected resulting in unrealistic results if foils are present A warning message is displayed if a foil is present 2 The tool assumes that particles are fully stopped in the detector resulting in unrealistic results for thin detectors 53 3 Using SIMNRA 3 The tool displays energies of scattered particles and recoils if kinematically possible It does not display energies of nuclear reaction products 54 3 Using SIMNRA 3 11 Plot menu This section describes all plot related commands including all commands which are not accessible via menus Autoscaling If checked the plot will be scaled automatically to minimum and maximum if experimental data are imported or a new calculation is performed If unchecked the axis scales remain fixed
154. m require Adobe Acrobat or Acrobat Reader Adobe Acrobat Reader can be downloaded freely from the Adobe web site see section 3 13 for more details Reading spectrum data in Canberra s CAM file format requires the Genie 2000 software package See section 3 4 for more details The use of SRIM stopping powers requires the SRIM software package version SRIM 2003 or later SRIM can be downloaded freely from the SRIM home page see section 3 17 for details Installation The installation of SIMNRA requires administrator privileges SIMNRA is distributed with a setup program To install SIMNRA simply run the setup program and follow the instructions After running the setup program you should have obtained the files listed in Table 2 1 To register run SIMNRA click Help Register and enter your registration number in the appropriate field 2 3 Uninstalling SIMNRA SIMNRA is shipped with an automatic uninstall program Refer to your Microsoft Windows documentation on how to uninstall programs 2 Installation Directory Files SIMNRA EXE Executable program README TXT Readme file CHANGES 6 0 TXT Describes the changes since version 5 0 CHANGES 5 0 TXT Describes the changes since version 4 4 CHANGES 4 4 TXT Describes the changes since version 3 0 LICENSE TXT Product license agreement MANUAL PDF This manual DESTINATION TXT For internal use by the help system libxml2 dll iconv dll dynamic link libraries for reading
155. medium energy formula which is valid only in the range 10 keV amu 1 MeV amu also at higher energies E gt 1 MeV amu The difference between the two formulas usually is small This switch is necessary because the two stopping power formulas do not fit smoothly together at 1 MeV amu The stopping power jumps at 1 MeV amu resulting in artificial kinks and steps in the simulated spectra This problem is overcome if High energy stopping is unchecked however this will result in less accurate stopping powers for energies gt 1 MeV amu A better solution is to use the Ziegler Biersack stopping powers where this problem does not occur This switch does not have any influence on the calculation of the stopping power of helium ions and is disabled For helium ions always the medium energy formula is used which is valid for all energies below 10 MeV The default is checked Energy loss straggling model Selects the electronic energy loss straggling model Bohr s theory Chu s theory or Chu Yang s theory can be used Chu s theory takes deviations from Bohr straggling caused by the electron binding in the target atoms into account and Yang s theory additionally incorporates charge state fluctuations of the ions See subsection 4 8 2 for more details about electronic energy loss straggling Chu Yang s theory is recommended Screening to Rutherford cross section Selects the screening function to the Rutherford cross section due to partial screening of
156. ments Get Property NumberOfElements lay Integer Integer Description Number of different elements in layer number lay NumberOfElements is readonly Parameters lay Number of the layer with 1 X lay NumberOfLayers 181 A OLE automation reference NumberOfLayers Get Property NumberOfLayers Integer Description Total number of layers in the target NumberOfLayers is readonly SubstrateRoughness Get Set Property SubstrateRoughness Double Description FWHM of the substrate roughness deg Target SubstrateRoughnessDistribution must be 0 or Target HasSubstrateRoughness must be true otherwise Sub strateRoughness has no effect Related Properties and Methods Target HasSubstrateRougness 180 Target SubstrateRoughnessDistribution 182 SubstrateRoughnessDistribution Get Set Property SubstrateRoughnessDistribution Integer Description Distribution function of the substrate roughness Allowed values are 0 Smooth substrate Substrate roughness is switched off Same as Tar get HasSubstrateRoughness false 1 Lorentzian roughness distribution Same as Target HasSubstrateRoughness true 2 Gaussian roughness distribution The FWHM of the substrate roughness is set with Target SubstrateRoughness Related Properties and Methods 182 A OLE automation reference Target HasSubstrateRougness 180 Target SubstrateRoughness 182 A 5 2 Methods AddElement Function AddElement
157. most independent of the ion energy For lower SIMNRA versions before 3 30 used the equation Age AS AR 4 55 x dE instead of Equation 4 54 Equation 4 55 is obtained by a taylor expansion of e around e considering only the linear term de 6ji Er 4 56 where de dE is the derivative of the stopping power and Ax the layer thickness e Ax is the energy loss in the layer By putting the above equation into Equation 4 54 we obtain Equation 4 55 The difference between Equation 4 54 and the previously used Equation 4 55 is only 1 296 because of the relatively small stepwidths used by SIMNRA 95 4 Physics E M ke V amu 5000 3000 2000 1500 H E M Z Figure 4 6 The Chu straggling correction for several values of E M as a function of the nuclear charge of the target Z Dots are original data from Chu 46 solid lines are extrapolated data taken from 39 ion energies the Bohr straggling is multiplied by the Chu correction factor H E M Z which depends only on E M and the nuclear charge of the target atoms Z5 H takes into account the deviations from Bohr straggling caused by the electron binding in the target atoms Chu 50 46 has calculated H by using the Hartree Fock Slater charge distribution This calculation gives straggling values which are considerably lower than those given by Bohr s theory The correction factor H as used by SIMNRA if Chu straggling is selected is s
158. n Equation 4 26 and Equation 4 29 is small in most cases The main problem using Equation 4 29 is that the first and second derivatives of Equation 4 26 and Equation 4 29 do not fit smoothly together at 1 MeV amu This may result in the appearance of kinks in the spectrum Nuclear stopping for incident hydrogen deuterium and tritium ions is negligible for incident energies above about 10 keV amu 3 and is neglected by SIMNRA 85 4 Physics Helium If Andersen Ziegler stopping is selected then for incident He and He ions the electronic stopping power data by Ziegler 4 are used for all elements The electronic stopping power S in eV 10 atoms cm for incident He ions with energy E in keV is given by 1 1 4 30 S SLow SHigh with Stow 41 E 4 31 and A3 A SHigh E In 1 E T ASE 4 32 A1 As are fitting coefficients and tabulated in 4 They are stored in the file STOPHE DAT Equation 4 30 to Equation 4 32 are valid for 1 keV lt E 10 MeV He stopping at higher energies above 10 MeV is not implemented in the program The stopping power of He is identical to the stopping power of He at the same velocity 4 The stopping power of He with energy E is obtained by taking the stopping power value at the energy E He 4 3 E He The stopping power for He is valid in the energy range 10 keV lt E lt 7 5 MeV Nuclear stopping for incident helium ions is calculated with the Krypton Carbon Kr C pot
159. n by the integral equation dE E x Eg f ELL d x 4 19 B dx Here we assume that the particle starts with initial energy E at the surface x 0 and dE dx E x x is the energy and depth dependent stopping power x is the path length into the material measured in areal density 10 atoms cm By differentiating Equation 4 19 we obtain the differential equation ud e E 4 20 dx where this is the defining equation for e E the energy dependent stopping cross section All SIMNRA versions before 5 70 used the algorithm of Doolittle for the evaluation of energy loss initially developed for the RUMP program 17 Doolittle expands the particle energy into a Taylor series and the energy E after a layer of material with thickness Ax is given by dE 1 HE L 30 F E Ep Ax Eo SC qa E Ax Da Eo 4 21 where el de dE is the first and e d e dE the second derivative of e e e and e are evaluated at the incident energy Po The terms in Equation 4 21 look as follows dE Se e 4 22 dx de dEdx l d E d de de dii qee du da ze e ele 4 24 With e e and e evaluated at Eg This gives the final result ee ee ae um E Eo Axe gar ee Ar e e e 4 25 el and e were calculated by SIMNRA by numerical differentiation of the stopping power data Mayor disadvantage of Equation 4 25 is the need of the first and second derivative of the stop
160. n calcula tions 4 11 1 Live time correction An Analog Digital Converter ADC requires a certain time to digitize an incident analog pulse While the pulse is being processed the ADC is not able to accept another pulse this pulse is rejected The time during which the electronics is busy and unable to accept a pulse is called dead time Tpeaq The live time Tjj is the time during which the electronics is able to accept pulses while the real time of a measurement is called Tout These times are connected through the relation Treat Trive Tpead A pile up rejector which rejects overlapping pulses is an additional source of system dead time The probability of a pulse to be detected is given by P _ Trive Live Tua 4 85 because it is accepted only if it arrives during the system live time interval If a live time correction is applied to simulated spectra by checking Apply live time correction in the Live time and pile up form section 3 6 2 then the initial number of simulated counts a in channel k is multiplied by the probability that the counts actually are detected to give the final number of simulated counts ng ny Prive n 4 86 n is the number of counts which would be detected for an indefinitely small incident count rate or an indefinitely fast ADC Note that the live time correction is applied to simulated spectra and not to experimental data SIMNRA does not modify experimental spectra 126
161. nchecked Diameter of incident beam Diameter of the incident beam in mm Please note that the size of the beam spot on the sample surface is d cosa Shape of incident beam Circular or rectangular beams may be selected A homogeneous current distribution of the incident beam is assumed Diameter of detector aperture Diameter of the detector aperture in mm Shape of detector aperture Circular or rectangular apertures may be selected Use rectangular also for long narrow slits Distance sample detector aperture Distance between the sample surface and the detector aperture in mm Note If Straggling in the Setup Calculation menu is unchecked then geometrical straggling and electronic energy loss straggling are neglected 16 3 Using SIMNRA detector incident beam Figure 3 4 Detector geometry d is the diameter of the incident beam w the width of the detector aperture and Lp the distance between sample and the detector aperture Incident angle a and exit angle f 17 3 Using SIMNRA Live time and pile up The parameter for a live time correction and pile up simulation are entered in this menu If experimental data are read from Canberra s CAM files some parameters are taken from the information stored in the files Apply live time correction Check if a live time correction should be applied to simulated spectra After checking Apply live time correction you have to enter values for real a
162. nd live time Calculation of pile up is only possible if Apply live time correction is checked Real time Real time of the measurement in s The real time is the time it took to measure the spectrum The real time is necessary for live time corrections and pile up calculations If Canberra s CAM files are used this parameter is taken from the file Live time Live time of the measurement in s The live time is the time interval during the measurement the analog digital converter ADC was able to accept pulses This value can be obtained from your multi channel analyzer MCA The live time is almost identical to the real time for low pulse rates The live time is only necessary for live time corrections and can be set identical to the real time if a pile up calculation is desired without knowing the correct live time If Canberra s CAM files are used this parameter is taken from the file Calculate pile up Check if pulse pile up should be calculated for simulated spectra After checking Calculate pile up you have to enter a value for the pulse rise time or the fudge time parameter Calculate pile up is only available if Apply live time correction is checked Note The pile up calculation will give incorrect results for ADC offsets other than zero Pulse rise time Rise time of the amplified pulse from zero to its maximum value in us See Figure 3 5 for a schematic definition of the pulse rise time For Gaussian pulse shaping the p
163. nd y in RUMP This angle is always independent in SIMNRA i e SIMNRA always uses general geometry while RUMP determines this angle from y 0 in IBM geometry or cos sj cos cos 0 in Cornell geometry These relations are summarized in Table 3 8 See Figure 3 3 for a graphical representation of the different angles SIMNRA adjusts the angles correctly if a RUMP RBS file is opened Sample Description Files SIMNRA supports only a subset of the RUMP sample description commands The supported command are listed in Table 3 9 All other commands will be neglected Note that especially the RUMP commands Equation Species and Fuzz are not supported If your sample description file contains these commands they will be neglected and a warning will be shown 58 3 Using SIMNRA SIMNRA RUMP Relation Incident angle a e a 0 Scattering angle 0 dh 0 180 q Exit angle p Y B 0 IBM geometry cos f cos cos O Cornell geometry P y General geometry Table 3 8 Naming conventions for the geometry of an experiment as used by SIMNRA and RUMP and the relations between them RESET LAYER OPEN NEXT COMPOSITION THICKNESS ABSORBER Partly implemented Only elements are recognised but no isotopes The command Composition Si 1 O 2 will be recognised and the natural isotopic ratios for Si and O will be used The command Composition 28Si 1 160 2 will not be recognised properly RUMP allo
164. near interpolation between the data points 68 3 Using SIMNRA 3 19 Energy calibration issues 3 19 1 Detector nonlinearity A solid state detector which is used in most ion beam experiments does not measure the real particle energy but a somewhat smaller energy This has been called pulse height defect The pulse height defect is due to 1 The energy and particle dependent energy loss in the top electrode and the dead layer of the semiconductor detector 13 14 15 2 Only the electronic energy loss in the active detector region is measured while nuclear energy loss is not detected 13 The nuclear energy loss is energy and particle dependent 3 Heavy ions produce a high density of electron hole pairs The electron hole pairs may recombine before separation by the electric field in the detector This has been called plasma effect 13 The plasma effect is energy and particle dependent The energy dependence of the pulse height defect results in a nonlinearity of the energy calibration The energy loss in the top electrode and the dead layer can be accounted in the following way You can create a foil consisting of two layers in front of the detector Layer 2 is composed of the material of the top electrode usually Au and has the thickness of the electrode usually the thickness is supplied by the manufacturer of the detector Layer 1 is composed of silicon in the case of a silicon detector and has the thickness of the d
165. neglected without severe loss of accuracy But it should be kept in mind that the used approximation gets invalid for grazing incidence or exit angles as is the case in ERDA in these cases correlation effects may be dominant and can change the shape of the spectra considerably The effect of layer roughness on the shape of RBS spectra is shown in Figure 4 17 for incident He ions backscattered from a gold layer at a scattering angle of 165 The film thickness distributions are described by the Gamma distributions shown in Figure 4 16 If the thickness variation is much smaller than the mean film thickness d 0 1 only the low energy edge of the film is affected by the roughness and gets broader With increasing roughness the broadening of the low energy edge increases until at o d 0 6 the high energy edge begins to decrease The energy Ei at which the low energy edge has decreased to its half height remains fairly constant until large roughness amplitudes of the order c d 0 6 i e until the high energy edge begins to decrease For sufficiently thick films i e if the film is completely resolved this energy is therefore a rather robust measure of the mean film thickness even for large roughnesses as long as the high energy edge is not affected The energy spectrum of 1 5 MeV He backscattered from a rough Ni film deposited on polycrystalline carbon is shown in Figure 4 18 The measured spectrum is well reproduced 113 4 Physics
166. nergetic hydrogen atoms from the nuclear fusion plasma to 7 5 x 10 Al atoms cm At the same time the Al film was oxidised and some nickel which was initially eroded at an erosion dominated area of the JET vessel wall was redeposited on the AI film and incorporated The observed spectrum with the tails at the low energy sides of the O Al and Ni peaks cannot be reproduced by assuming a smooth layer But it is fairly well reproduced by a rough layer with a mean film thickness of 1 11 x 101 atoms cm roughness o 1 06 x 101 atoms cm and composition 68 Al 30 O 2 Ni solid line in Figure 4 19 The shape of the film thickness distribution is close to the curve with o 1 in Figure 4 16 This example shows clearly that non Gaussian distributions of layer thicknesses are observed in practice and can be described by a Gamma distribution 4 10 2 Smooth film on a rough substrate A film with homogeneous thickness d on a rough substrate is shown schematically in Fig ure 4 15b The substrate is considered to be rough if its roughness amplitude is much larger The JET vessel walls consist of Inconel a stainless steel with high nickel content 116 4 Physics SIR RIL Wises ES SS May DLT Ee 77 TS PT ERN LA SN ELIO Figure 4 20 Schematic representation of a rough surface In Direction of the incident beam Out Direction of the outgoing beam Light gray Plane spanned by the inci
167. ntained in the Setup Calculation form is saved The NRA data file format is used for saving Save as Default The current setup for calculation is stored as startup default for SIMNRA in the file DEFAULT CALC NRA Save Setup as Save the current setup to file Read Setup Reads a setup from file Note You can read any NRA file with Read Setup Only the calculation information will be read any other information such as target composition experimental spectra etc which may be present in the NRA file will be ignored 27 3 Using SIMNRA 3 7 Target menu 3 7 1 Target Target In this menu the target is created A target consists of layers Each layer consists of different elements and has some thickness The composition of a layer does not change throughout his thickness To simulate a concentration profile you have to use multiple layers The layer number 1 is at the surface of the target the layer number 2 is below layer 1 and so on see Figure 3 8 Thickness Thickness of the layer in 107 atoms cm The conversion factor from ug cm or um to atoms cm can be determined with Calculate Density for pure elements Number of Elements Number of different elements in this layer The maximum number of different elements in a layer is 20 Element Name of the element for example Si W Au Lowercase and uppercase letters in elements names are treated similar you can enter silicon as Si si SI or sI XX means tha
168. o App CalculateSpectrum Parameters None Return Value Returns true if the calculation succeeded Related Properties and Methods App CalculateSpectrum 156 App CalculateSpectrumToDepth 157 App DeleteSpectrumOnCalculate 152 CalculateSpectrumToDepth Function CalculateSpectrumToDepth Depth Double Boolean Description 157 A OLE automation reference Calculates a simulated spectrum until a specified depth The calculation is finished when the specified depth is reached CalculateSpectrumToDepth is identical to CalculateSpectrum but it is considerably faster for small values of Depth Calcu lateSpectrumToDepth should not be used for spectrum simulation but can be used for depth resolution calculations and the like Parameters Depth Maximum depth of calculation 10 atoms cm Return Value Returns true if the calculation succeeded Related Properties and Methods App CalculateSpectrum 156 App CalculateSpectrumFast 157 App DeleteSpectrumOnCalculate 152 CopySpectrumData Procedure CopySpectrumData Description Copies experimental and simulated spectra in ASCII format to the Windows clipboard See Edit Copy Data in section 3 5 for a description of the format Parameters None Return Value None Related Properties and Methods App WriteSpectrumData 164 158 A OLE automation reference FitSpectrum Function FitSpectrum Boolean Description Fits a spectrum You have to adjust the f
169. o find out which particles are involved in the nuclear reaction The masses of the particles are ignored The original specification can be found in DSIR Physical Sciences Report 33 by I C Vickridge 62 3 Using SIMNRA COMMENT These cross sections have been digitised from the publication cited below No error of either the energy and or the sigma is given Some errors may be among the data we are recently checking them The Los Alamos lon Beam Handbook also will contain these data as soon as it is ready If you use this data please refer to the paper below Source A Turos L Wielunski and a Batcz NIM 111 1973 605 Special comment WARNING THIS IS MAINLY FOR TEST NO GUARANTY IS PROVIDED FOR EVEN AGREEMENT WITH THE ORIGINAL PUBLICATION File created by R33 Manager version 0 1 Version R33 Source A Turos L Wielunski and a Batcz NIM 111 1973 605 Name Gyorgy Vizkelethy Addressi Department of Physics Address2 Idaho State University Address3 Campus Box 8106 Address4 Pocatello ID 83209 8106 Address5 208 236 2626 Address6 vizkel physics isu edu Serial Number 0 Reaction 160 d a0 14N Distribution Energy Composition Masses 2 000 16 000 4 000 14 000 Zeds 1 8 2 7 Qvalue 3110 00 0 00 0 00 0 00 0 00 Theta 145 00 Sigfactors 1 00 0 00 Enfactors 1 00 0 00 0 00 0 00 Units mb Data 761 0 0 0 2 92E 0000 0 0 770 0 0 0 3 65E 0000 0 0 775 0 0 0 3 99E 0000 0 0 780 0 0 0 4 41E 0000
170. oil layer Return Value Returns the energy loss in the layer keV Related Properties and Methods TargetID 196 Stopping StoppingInLayer 198 StoppingInElement Function StoppingInElement Z1 Integer M1 Double E Double Z2 Integer Double Description 197 A OLE automation reference Stopping power of an ion Z1 in element Z2 The stopping power model is selected with Calc ZBStopping page 178 and Calc HighEnergyStopping page 174 Parameters Zl Nuclear charge of the ion M1 Mass of the ion amu E Incident energy keV Z2 Nuclear charge of the target element Return Value Returns the stopping power in element Z2 keV 10 atoms cm Related Properties and Methods Calc ZBStopping 178 Calc HighEnergyStopping 174 StoppingInLayer Function StoppingInLayer Z1 Integer M1 Double E Double TargetID Integer lay Integer Double Description Stopping power of an ion Z1 in a target or foil layer The stopping power model is selected with Calc ZBStopping page 178 and Calc HighEnergyStopping page 174 and may be additionally modified by a correction factor to the stopping power see section 3 7 Parameters Zl Nuclear charge of the ion 198 A OLE automation reference M1 Mass of the ion amu E Incident energy keV TargetID Selects target or foil lay Number of the target or foil layer Return Value Returns the stopping power in the layer keV 10 atoms cm Relat
171. omation reference Default Value 20 Description Maximum number of fit iterations Fitting will be performed until the desired accuracy is obtained or the maximum number of iterations is reached Related Properties and Methods Fit Accuracy 187 NumberOfRegions Get Set Property NumberOfRegions Integer Default Value 1 Description Number of different regions where y is calculated see subsection 3 9 1 At least one region must exist and the regions should not overlap The lower and upper channels of the regions are specified by the Fit RegionMinChannel and Fit RegionMaxChannel properties Related Properties and Methods Fit RegionMaxChannel 191 Fit RegionMinChannel 191 ParticlesSr Get Set Property ParticlesSr Boolean Default Value false 190 A OLE automation reference Description Specifies if the number of incident particles times solid angle is fitted The number of incident particles times solid angle is fitted if ParticlesSr is true RegionMaxChannel Get Set Property RegionMaxChannel reg Integer Integer Default Value 8192 Description Upper channel of fit region number reg Related Properties and Methods Fit NumberOfRegions 190 Fit RegionMinChannel 191 RegionMinChannel Get Set Property RegionMinChannel reg Integer Integer Default Value 1 Description Lower channel of fit region number reg Related Properties and Methods Fit NumberOfRegions 190 Fit
172. operty RealTime Double Description Real time of a measurement s Related Properties and Methods Setup LiveTime 167 Setup LTCorrection 168 RiseTime Get Set Property RiseTime Double 169 A OLE automation reference Description Rise time of the amplified pulse from zero to its maximum value us See section 3 6 2 for details Related Properties and Methods Setup PUCalculation 168 Setup PURResolution 169 Theta Get Set Property Theta Double Description Scattering angle 0 deg Related Properties and Methods Setup Alpha 164 Setup Beta 165 TOFLength Get Set Property TOFLength Double Description Length of the flight path for a time of flight detector m This value is only used if Setup DetectorType is set to time of flight detector Related Properties and Methods Setup DetectorType 167 Setup TOFTimeResolution 171 TOFTimeResolution Get Set Property TOFTimeResolution Double 170 A OLE automation reference Description Time resolution of a time of flight detector ps The full width at half maximum FWHM has to be used This value is only used if Setup DetectorType is set to time of flight detector Related Properties and Methods Setup DetectorType 167 Setup TOFLength 170 A 3 2 Methods SetBeta Function SetBeta Geometry Integer Double Description Sets the exit angle fj as function of incident angle a and scattering angle 0 for IBM and Cornell
173. or a smooth layer but with angles and f is calculated Incident angles amp gt 90 are excluded This represents a line segment which cannot be hit by the incident beam As in the case of a rough film on a smooth substrate surface correlation effects like shadowing of one line segment by another and multiple surface crossings are neglected In IBM geometry with a f 0 180 the local exit angle for a given inclination angle p is given by B B 9 4 82 This relation was used by SIMNRA 4 70 4 90 and ref 79 But this choice of is only valid in IBM geometry and results in unrealistic spectra if a rough surface is bombarded at non normal incidence in non IBM geometry SIMNRA 5 00 5 20 used a more general approach where the 118 4 Physics correct relation between the angles in any geometry and even the 3 dimensional nature of a rough surface were taken into account by rotating the inclined line segments and calculating an averaged ff Although more accurate than Equation 4 82 it turned out that this approach suffered from numerical instabilities at non normal incident angles a gt 30 and non IBM geometry In SIMNRA 5 25 the choice of was changed again and is calculated in the following way 1 For each inclination angle the local angle of incidence amp is calculated according to Equation 4 81 The azimuth angle Y between the incident and exit beams is calculated from _ cos cos cosa 4 83 sin
174. or larger energy losses however the beam width gets skewed 97 4 Physics 2 5 MeV He in Si e 1 0 20 Straggling keV FWHM 0 1 2 3 4 Depth 10 atoms cm Figure 4 7 Beam width FWHM of 2 5 MeV He ions penetrating through silicon The solid line is the beam width calculated by SIMNRA using Equation 4 57 the dashed line is the prediction of Bohr s theory The vertical lines denote the mean depth at which the beam has lost 1096 20 and 50 of its initial energy Max denotes the depth at which the mean energy of the beam has decreased to the energy of the stopping power maximum 98 4 Physics 1 0 MeV He in Au Max 20 50 Straggling keV FWHM 0 2 4 6 8 10 Depth 10 atoms cm Figure 4 8 Beam width FWHM of 1 0 MeV He ions penetrating through gold The solid line is the beam width calculated by SIMNRA using Equation 4 57 the dashed line is the prediction of Bohr s theory The vertical lines denote the mean depth at which the beam has lost 20 50 and 90 of its initial energy Max denotes the depth at which the mean energy of the beam has decreased to the energy of the stopping power maximum 99 4 Physics Figure 4 9 shows the measured RBS spectrum for 1 0 MeV He ions incident on a gold layer with a thickness of about 100 nm and a scattering angle of 165 compared with simulations using Bohr straggling and Chu straggling As can be seen at the low energy edge of the layer the Bo
175. ory angle with respect to the incident beam so that backscattering would be 1807 Energy gives the laboratory energy of the incident beam If both entries are present an illegal condition then only the entry corresponding to the keyword in the Distribution entry will be used O 1 0 0 0 rr Note Scale conversion factor and its associated error common to all the cross section data See original R33 publication in Appendix 1 for discussion 209 Units Enfactors Nvalues Data Enddata B The R33 cross section file format O Cmb String Note Valid values are mb rr and tot R33 files are always in mb sr or units proportional to mb sr for differential cross sections and mb for total cross sections The constant of proportionality given in the enfactors entry is independent of energy Some users find it preferable to have elastic scattering cross sections relative to the Rutherford cross section Since the conversion factor is no longer energy independent the enfactors entry can no longer cater for this In this case the units entry should specify ri for ratio to Rutherford Nevertheless it is recommended that elastic cross sections be stored as cross sections just like the inelastic scattering cross sections i e in mb sr The value tot indicates that the cross section is integrated over all angles and is expressed as a function of energy Thus if rot is used as a unit then the distribu
176. ough film on a smooth substrate A rough film on a smooth substrate is shown schematically in Figure 4 15 a The substrate can be considered to be smooth if its roughness is much smaller than the mean thickness d of the film The film thickness distribution is described by a distribution function p d with the film thickness d measured perpendicular to the substrate see Figure 4 15 a and d gt O In the literature usually a Gaussian distribution centered at d with variance o and cut off at zero is used for p d 74 75 However a more natural choice of a distribution function with only 111 4 Physics a ion beam b ion beam Figure 4 15 Schematic representation of a rough film on a smooth substrate a and of a smooth film on a rough substrate b positive values d gt 0 is the Gamma distribution which is also fully described by its mean value d and standard deviation c The Gamma distribution is defined by a p d ar ef d 0 4 78 P a with a d o and B d o T a is the Gamma function The Gamma distribution is shown in Figure 4 16 for d 1 and different standard deviations c The corresponding Gaussian distributions centered at 1 and identical are shown for comparison If o lt d i e if the width of the distribution is small compared to its mean value Gaussian and Gamma distributions are nearly identical see the curves for c 0 1 in Figure 4 16 With increasing the two distributions get more
177. p a Be 90 2650 7100 10BPA1_2 R33 Jenkin 1964 V B D aj Be 156 980 1800 10BDAO R33 Purser 1963 Tipp o Be 156 980 1800 10BDA1 R33 Purser 1963 BCOHe RE 90 2000 4000 BIOHE3POT90 R33 McIntyre 1996 43 3 Using SIMNRA 0 Lab Energy keV File Reference PBHe p C 90 2000 4000 B10HE3P1T90 R33 McIntyre 1996 B He pp C 135 2000 4000 B10HE3P0T135 R33 McIntyre 1996 PB Hep C 135 2000 4000 B10HE3P1T135 R33 McIntyre 1996 PB Hep C 90 1300 5000 10BTPO R33 Schiffer 1956 10B He p C 90 1300 5000 10BTP1 R33 Schiffer 1956 B a po EC 90 1400 5300 10BAPO_1 R33 Chen 2003 PB a p C 135 4000 5000 10BAPO R33 Giorginis 1995 PB a p C 135 4000 5000 10BAP1 R33 Giorginis 1995 UB p aj Be 155 700 6000 11BPAO R33 Symons 1963 B p ay Be 165 1700 2700 11BPAO 1 R33 Mayer 1998 BCHe po C 90 2000 4000 B11HE3P0T90 R33 McIntyre 1996 B Hepj PC 135 2000 4000 B11HE3P0T135 R33 McIntyre 1996 NBCHe po PC 90 3000 5400 11BTP0 R33 Holmgren 1959 BC ep 90 3000 5400 11BTP123 R33 Holmgren 1959 BP He DJ PC 90 3000 5400 11BTD0 R33 Holmgren 1959 2C D p C 135 520 2950 12CDP_1 R33 Jarjis 1979 Eng 165 800 1950 12CDP_2 R33 Kashy 1960 PCCHe po N 90 2100 2300 12CTPO R33 Tong 1990 PCCHep N 90 2100 2400 12CTP1 R33 Tong 1990 I C 5He p N 90 2100 2400 12CTP2 R33 Tong 1990 12C He po N 159 4 1800 5400 12
178. p width control is used see subsection 3 6 3 A more accurate approximation than Equation 4 11 is obtained by integrating Equation 4 11 NAQ Q o E x dx 4 12 cosa J NAQ P dx o E dE 4 13 cosa Jy dE with xg and x4 the start and end depths of the thin layer and Ey E x0 E E x the corresponding energies By assuming a constant stopping power S dE dx E throughout the layer we get E x Ey Sx and NAQ1 Ty Q o E dE 4 14 cosa S E Equation 4 14 is used by SIMNRA 5 02 and higher providing a higher accuracy and better stability than Equation 4 11 in the case of narrow structures in the cross section While Equation 4 11 neglects all stopping power effects Equation 4 14 takes a constant stopping power into account neglecting effects due to the variation of the stopping power 77 4 Physics 4 4 Cross section data 4 4 1 Rutherford cross sections The Rutherford cross section for backscattering is given in the laboratory system by 2 1 2 2 m2 Misin 9 M cos0 ZZ Or mb sr 5 1837436 x 10 zen 4 15 E keV M sin 0 m3 M2 sin 8 s 0 is the scattering angle Z and M are the nuclear charge and the mass of the projectile respectively and Z and M are the nuclear charge and the mass of the target atom respectively Op is the differential cross section in the laboratory system Experimental measurements indicate that actual cross sections deviate from Ruth
179. parameters Simnra Spectrum Experimental and simulated spectra Plot properties Simnra Stopping Stopping powers energy loss and straggling in elements and layers Properties and methods SIMNRA exports the following OLE automation properties and methods grouped by object Simnra App Active Specifies whether SIMNRA is active and has focus BringToFront Brings SIMNRA to the front above all other applications CalculateSpectrum Calculates a simulated spectrum CalculateSpectrumToDepth Calculates a simulated spectrum until a specified depth 145 A OLE automation reference CalculatingSpectrum Indicates if a spectrum is being calculated CopySpectrumData Copies experimental and simulated spectra in ASCII format to the Windows clipboard DeleteSpectrumOnCalculate Specifies whether the current simulated spectrum is deleted if a new calculation is performed FileName Name of the nra file FitSpectrum Fits a spectrum Height Height of the form in pixels Hide Hides SIMNRA LastMessage Text of the last error message or warning Left Left side of the form relative to the screen in pixels Maximize Maximizes SIMNRA to fill the whole screen Minimize Minimizes SIMNRA to the Windows task bar Open Opens a NRA file ReadSpectrumData Imports experimental data in different data formats Restore Restores the minimized application to its normal
180. ping power Stopping powers supplied by the SRIM program don t have smooth derivatives and the use of Equation 4 25 can result in large errors see below Moreover Equation 4 25 does not provide a criterion how to select the step width Ax in order to obtain a desired accuracy and it does not provide an error estimate Therefore Equation 4 25 was replaced by a more accurate and stable Runge Kutta algorithm in SIMNRA 5 70 12 Equation 4 20 is a first order differential equation with initial values 82 4 Physics 2000 T T Precise Step width 100 keV Runge Kutta 1500 Doolittle gt o E gt 1000 4 o p o c W500 0 t 60r E 40r E 2 2 204 J L J P o o gt 20r 4 5 20 2 sol J Ww 60 L 4 0 0 0 5 1 0 1 5 2 0 Depth DO atoms cm Figure 4 4 Slowing down of 2 MeV 4He in Au with Ziegler Biersack stopping calculated with different numerical methods Top He energy as a function of depth Bottom Error of the calculated energy The Precise result was obtained with a Runge Kutta method using a step width of 1 keV E x 0 Ej and dE dx x 0 e Eg SIMNRA uses a fifth order Runge Kutta method with embedded forth order Runge Kutta with Cash Karp parameters for an error estimate and automatic step width control 12 The error is some eV for energy losses of the order of 1 MeV The energy loss of He ions in Au and the numerical error of the energy loss ca
181. position of layer number LayerNr is fitted if LayerComposition is true Only one layer can be fitted at the same time Related Properties and Methods Fit LayerNr 188 Fit LayerThickness 189 LayerNr Get Set Property LayerNr Integer Default Value 1 Description Specifies the number of the target layer which thickness or composition is fitted Only one layer can be fitted at the same time Fit LayerComposition and or Fit LayerThickness must be true otherwise layerNr has no effect Related Properties and Methods Fit LayerComposition 188 Fit LayerThickness 189 188 A OLE automation reference LayerRoughness Get Set Property LayerRoughness Boolean Default Value false Description Specifies if the roughness of a target layer is fitted The number of the layer is specified by the LayerNr property The roughness of layer number LayerNr is fitted if LayerRoughness is true Only one layer can be fitted at the same time Related Properties and Methods Fit LayerNr 188 Fit LayerComposition 188 LayerThickness Get Set Property LayerThickness Boolean Default Value false Description Identical to Fit LayerComposition see 188 Only used for backward compatibility with previous versions This method should not be used for new developments Related Properties and Methods Fit LayerNr 188 Fit LayerComposition 188 Maxlterations Get Set Property Maxlterations Integer 189 A OLE aut
182. ral geome try Geometrical straggling is only calculated for IBM and Cornell geometries SIMNRA will automatically determine if IBM or Cornell geometry is present Note that the beam spot size on the sample surface is d cos a 104 4 Physics Energy loss straggling geometrical straggling and the detector resolution are independent and are added quadratically Figure 4 11 gives as examples the different straggling contributions at the sample surface for 2 6 MeV He incident on Co 99Do 9 as a function of depth for typical RBS and ERDA geometries An energy independent detector resolution of 15 keV FWHM is used For RBS geometry the contribution of geometrical straggling is small compared to energy loss straggling and the resolution of the detector and may be neglected without penalty For the ERDA geometry however geometrical straggling cannot be neglected Note that geometrical straggling first decreases until it reaches zero and then increases again This is due to the minus sign in Equation 4 74 If the exit angle 6 decreases the outgoing path is closer to the surface normal then the scattering angle 0 increases The backscattered or recoiled particles start with a smaller energy However the path length in the material is smaller due to the exit angle which is closer to normal resulting in a smaller energy loss Near the surface the path lenght differences are small and geometrical straggling is governed by the kinematic spread With in
183. re EC TRIN TUE 55 M Rescale x Axis ooooooooomomomoo 55 Max iterations EE 50 Rescale y Axis eee 55 Multiple scattering 21 107 108 EENEG 55 N x Axis ee 55 NDF A 60 EEN ae Nuclear energy loss straggling see Straggling 218 Privileves coco ese yer eres see Installation Progress window seseseesss 56 Publications see SIMNRA Pulse height defect see Detector Pulse rise time see Rise time R R33 file format see Cross section data Reactions menu 34 Realtime ssss 18 52 126 Registration vii 3 57 Rise time i c ler ec EE e RN ke 18 52 Roughness see Surface roughness RTR file format see Cross section data RUMP escitas 58 71 82 RBS file eere is 9 58 sample description file 9 58 Runge Kutt en ei hne eh Rh res 82 Rutherford cross section see Cross section data S Scattering angle 12 14 Scattering kinematics see Kinematics Screening Andersen 23 78 LEGCUyet sais E EIER 23 78 Semiconductor detector seeDetectOr e E eee ree sss 215 Setup menu EEN her rwn 12 20 Calculation 0 ce cece eee eee 21 Exp riment osa EN SE RT XR 12 Experiment More Options Detector Geometry 16 Detector Type 15 Live Time and Pile up 18 SIMNRA publications ii feference end de eeneg ii version history
184. rgy overlap in cross sections All available cross section data are listed in Table 3 4 Table 3 5 and Table 3 6 If you want to add new cross section data files see section 3 16 Note 1 Some files contain total cross section data o E In these cases the differentiell cross section do dQ is obtained by SIMNRA for all kinematically allowed angles by assuming angular independence of the cross section in the center of mass system e po E 3 5 EAR grecs 3 5 This cross section is then transformed from the center of mass to the laboratory system The assumption of angular independence in the center of mass system is well fulfilled for the He D p a reaction for incident energies below about 1 2 MeV and for the DCHe p a reaction for incident energies below about 1 8 MeV Note 2 Use the data files that came with SIMNRA Some of the original data files at SigmaBase contain small format errors such as additional blank lines which confuse the program Note 3 Non Rutherford cross sections and nuclear reactions are only available if Isotopes in the Setup Calculation menu is checked 35 3 Using SIMNRA Table 3 4 Non Rutherford backscattering cross sections 0 Lab Energy keV File Reference D p p D 151 1800 3000 PH LA76A RTR Langley 1976 D p p D 2000 2800 HD165 LANGLEY R33 Langley 1976 TEDT 2500 3500 PH_LA76
185. roughness have been reviewed by Szil gy et al 39 40 and can be included in SIMNRA calculations The details are described in the following sections 93 4 Physics 4 8 2 Electronic energy loss straggling There are four main theories describing electronic energy loss straggling 41 42 43 each applicable in a different regime of energy loss With AE the mean energy loss of the beam and E the energy of the incident beam we can distinguish AE E lt 10 Vavilov s Theory 44 42 For thin layers and small energy losses The energy distribution is non Gaussian and asymmetrical This energy range is not described properly by SIMNRA 10 20 Bohr s Theory 45 46 As the number of collisions becomes large the distribution of particle energies becomes Gaussian 20 50 Symon s Theory 41 This theory includes non statistical broadening caused by the change in stopping power over the particle energy dis tribution If the mean energy of the beam is higher than the energy of the stopping power maximum then particles with a lower energy have a higher stopping power and particles with higher energy have a smaller stopping power This results in a nonstatistical broadening of the energy distribution The width of the particles energy distribution in Symon s theory is significantly higher than predicted by Bohr s theory The distribution of particle energies is still Gaussian 50 90 Payne s and Tschal rs Theory 47 48 49
186. rs Decimal points are represented only by full stops and not by commas as can be the case in some European countries The legal ascii character set for the purposes of R33 files is ascii O to ascii FE Apart from the Comment entry and the optional Version entry entries may be in any order Each entry ends with a carriage return line feed sequence Some entries are optional O most are required R and some are mutually exclusive Mx where all entries for which the value of x is the same are mutually exclusive See below for special conditions that apply to the keywords Comment Nvalues and Data and EndData Default values are suggested for R33 reading routines so that if an optional entry is omitted or if a required entry is unreadable or missing illegally the value of the corresponding variable in the reader is well defined All energies are expressed for the laboratory frame in keV and all angles in the laboratory frame in degrees English is the preferred language Special note on data entry order The original R33 specification called for data to be listed as x y xerrror yerror however the R33 files originally generated for the Sigmabase contained data entries in the order x xerror y yerror The original specification was intended to allow for files containing no error information to be smaller since the two final entries could simply be omitted However given that the Sigmabase data fits easily on a single floppy wi
187. s iaea org iband1 This library contains many cross section data files and is constantly updated The data files are in R33 format and can be used with SIMNRA 3 16 1 The R33 file format The R33 file format is described in full detail by I C Vickridge in the file R33Help htm which should be present in your SIMNRA installation directory and in Appendix B SIMNRA reads the updated R33 file format of April 2002 but is also able to read older R33 files which conform to the original specification from the year 19917 An example for a valid file in the R33 format is shown in Figure 3 12 Each line must end with CR LF Carriage Return and Line Feed SIMNRA uses not only the data points but also a part of the information supplied in the file header The following lines are used by SIMNRA and must be present in the file Though the lines may be arranged in any order it is recommended to arrange them in the same order as shown in Figure 3 12 Any other entries than the ones listed below are ignored by SIMNRA but may be necessary to form a valid R33 file See Appendix B or the file R33Help htm for details A line containing the string Source The rest of the line has to contain a reference or other source for the data and will appear as description in the reaction menu A line containing the string Reaction SIMNRA will interpret the nuclear reaction string written in that line In the example of Figure 3 12 160 d a0 14N t
188. s manual uuu oe sa x xor woke RA 1 1 2 Conventions in this mantal cocoa 2 2 Installation 3 2 1 System requirement a oce desse oec a ae we Ih e RR c a 3 ET EEN 3 223 Uninstalline SIMNRA oa 2 add oS host RR e oak a 3 3 Using SIMNRA 5 dolo Data AEN aa A A A ARA AAA 5 3 2 Toolbar 4 24 bx ede e Oe RE EN a ed E SUE bees 5 di REEL iusso Xe rece dec e Rh e e eec e qan 5 34 DUST Dr 7 2 5 Bit A E E EE eat E 11 A eae Burdeos 12 36 1 Setup Experiments ae use walk ee eue ew Y odere c Se wen qua e es 12 3 0 2 Setup Experiment More OptiDHS cuu a Rv th 15 3 6 3 Setup Calcula ga x e onm YoR a pO E A RS 21 3s Argel Meno M PED M EIL 28 Sela Targeto Target LC 28 3 7 2 Layer and substrate roughness o ooo ooo ooo o 30 3 20 Target Foils mo lor Rey e dE aa ard us ewe ee ER 2B Reaccions MENU aea ma as E EE 34 28 1 Replacement of cross section data files is suce ee eee AN 47 3 9 Calculate Men ee EE E EE e E EH od exu 48 Sms Pit Specuniiibu ir he qr e A E A 49 3 9 2 Subtracting pile up common ar Reed che D da 51 Contents STO OO MEMO st A E GP a Oe BE eS eG Ee RUP A dris n 53 3 10 1 Data EEN hee so A Rege 53 3 10 2 Integrate ect ius Seam Gla tows Say a do E e Gee a 53 3 10 3 Nearest Elements ec core cer gerinti reut bi RN E S Re de 53 SE Plot MENO do toas EUER PEE xe xx edu ESSE 55 3 12 0pti0ns menu uos Ge LE oe STEE E ER RUE TRE S Eum ew ade 56 o ere i dete date des 57 3 14 Data exchange
189. s of plural large angle scattering and surface roughness can be calculated approximately Data fitting layer thicknesses compositions etc is possible by means of the Simplex algorithm OLE automation allows automated analysis of large numbers of spectra In contrast to other programs for the simulation of backscattering spectra SIMNRA is easy to use due to the Microsoft Windows user interface SIMNRA makes full use of the graphics capacities of Windows 1 1 Organization of this manual This manual is organized in the following way System requirements and the installation of the program are described in chapter 2 The use of the program is described in chapter 3 A quick overview about the steps necessary to calculate a spectrum is given in section 3 3 More details are found in the rest of chapter 3 The physical concepts implemented in the program are described in detail in chapter 4 Some examples for the abilities of the program are shown in chapter 5 1 Overview 1 2 Conventions in this manual Links to sections figures pages references internet web sites and additional text files are highlighted in blue A click with the mouse will bring you to the link destination i 2 1 2 2 Installation System requirements SIMNRA requires Windows NT 2000 XP Vista or Windows 7 Super VGA resolution of 1024 x 768 pixels or higher SIMNRA requires about 20 MB free hard disk space User s Guide and help syste
190. shapes and the like In these cases the selection of Channels may result in poor results while Integrals still may work reliably Max Iterations Maximum number of Simplex iterations Fitting will be performed until the desired accuracy is obtained or the maximum number of iterations is reached Fit Accuracy Desired accuracy of the fit The fit has converged if the relative change of all fitted parameters and of y is below Fit Accuracy The relative change of a parameter A is AA A where AA is the difference between the best vertex the vertex with the lowest x and the worst vertex the vertex with the highest y Calculate Fit Error If checked an error estimate for all fitted parameters is computed See below for details This is a time consuming process and may require more computing time than the fit itself Default is unchecked 50 3 Using SIMNRA Fit error An error bar for fitted parameters can be obtained under the following assumptions 1 The physics model i e stopping powers cross sections etc is assumed to be accurate with zero error Obviously in reality this is not the case and errors introduced by inaccurately known stopping powers or cross sections may largely exceed the computed errors SIMNRA does not know whether a stopping power or cross section is accurate or not you should know that 2 All nonfitted parameters are assumed to be accurate with zero error Again usually this will be not the case
191. sina As scattering angle 0 and azimuth angle y are constant for a given geometry the local exit angle f can be calculated for a given local incident angle from COS B sin y sin 0 sin cos 0 cos 4 84 Equation 4 84 is valid for any geometry For a given local tilt angle v the calculation of the local incident and exit angles and P depends on the setting of the Dimension of substrate roughness switch see section 3 6 3 e 2 dimensional In the 2 dimensional model the local incident and exit angles amp and f are calculated according to Equation 4 81 and Equation 4 84 2 5 dimensional In the 2 5 dimensional model it is assumed that the surface consists of small planes which are tilted by a local tilt angle y and rotated by an angle w along the surface normal In a fully 3 dimensional surface model the local incident and exit angles and f depend on y and c and it would be necessary to calculate spectra for each possible combination of o and c In order to keep computing times short this is not done Instead for each tilt angle the average angles amp and f are used averaged over w Therefore the 2 5 dimensional model uses only one set amp f for each y as would be the case in the 2 dimensional case but this set is obtained by averaging a 3 dimensional surface model The accuracy of the 2 5 dimensional model is therefore somewhere in between a 2 dimensional and a fully 3 dimensional model Which d
192. size SaveAs Saves a NRA file Show Shows SIMNRA if it was hidden ShowMessages Specifies if error messages are shown SpectrumChanged Indicates if the calculated spectrum has changed i e was re calculated Top Top side of the form relative to the screen in pixels Width Width of the form in pixels WriteSpectrumData Writes all spectra experimental simulated in ASCII format to a file 146 A OLE automation reference Simnra Setup Alpha Incident angle deg Beamspread Energy spread of incident beam keV FWHM Beta Exit angle deg CalibrationLinear Linear calibration term B for energy calibration see Equation 3 1 keV channel CalibrationOffset Calibration offset A for energy calibration see Equation 3 1 keV CalibrationQuadratic Quadratic calibration term C for energy calibration see Equa tion 3 1 keV channel DetectorResolution Detector resolution keV FWHM DetectorType Type of detector solid state time of flight Energy Energy of incident ions keV LiveTime Live time of a measurement s LTCorrection Specifies if a live time correction is applied ParticlesSr Number of incident particles times solid angle sr PUCalculation Specifies if pile up is calculated PUROn Pile up rejector on or off PURResolution Pile up rejector pair resolution time us RealTime Real time of a measurement s R
193. state detector Detector thickness Thickness of the SSD detector in um Select Infinity if the particles are fully stopped in the detector Material Detector material Silicon detectors are assumed This cannot be changed Time of flight detector Free flight path Length of the flight path for which the time of flight is measured in m Time resolution Time resolution of the TOF detector in ps The full width at half maximum FWHM has to be used The time resolution is used to calculate the energy resolution of the TOF detector see subsection 4 7 1 Electrostatic detector Delta E E The energy resolution of electrostatic detectors is usually given by a constant ratio AE E with AE the energy resolution in FWHM and E the particle energy See also subsection 4 7 2 15 3 Using SIMNRA Detector Geometry In this menu the detailed geometry of the detector beam diameter detector diaphragm width distance sample detector and shapes of incident beam and detector diaphragm is entered This is only necessary if geometrical straggling due to finite widths of the incident beam and detector diaphragm should be calculated Geometrical straggling is usually small for RBS but may be considerable for ERDA See Figure 3 4 for details how distances and diameters are measured Calculate geometrical straggling Check to include geometrical straggling in the simulation Geometrical straggling is neglected if his box is u
194. stopping power calculations have been taken from the SRIM source code the input data have been taken from the SRIM distribution For incident hydrogen and helium ions SIMNRA therefore uses exactly the same electronic and nuclear stopping powers as the SRIM program For incident heavy ions however there are small differences between SIMNRA and SRIM SRIM uses linear interpolation for some input data resulting in stopping powers with a noncontinuous derivative SIMNRA uses spline interpolation instead of linear interpolation resulting in stopping powers with continuous second derivative The stopping powers calculated by SIMNRA are therefore more smooth than the original stopping powers calculated by SRIM the differences are typically below 196 3For low energetic hydrogen ions E lt 10 keV there are differences because SIMNRA neglects nuclear stopping of hydrogen 89 4 Physics 4 6 3 KKK stopping As was shown by Konac et al 7 8 the SRIM 97 stopping power values which are used by SIMNRA if Ziegler Biersack stopping is selected are somewhat inaccurate for the stopping of ions in C and Si Konac et al fitted their experimental values with the formulas SE E ln e BE P E P E ag a EY aE a4EV 5 4 49 where the constants a and s are tabulated in 8 S is the electronic stopping E is in MeV amu and S is in eV 10 atoms cm The fit is valid in the range 0 01 lt E lt 100 MeV amu SIMNRA uses the
195. t this element is unknown The special symbols D for deuterium T for tritium and A for He can be used Concentration or areal density Atomic concentration or areal density of the element in the actual layer The concentration c must be 0 0 c lt 1 0 The sum of the concentrations of all elements in one layer must be equal to 1 0 999 lt ic lt 1 001 If the sum of concentrations is not equal to 1 the word concentration is written in red colour if the sum of concentrations is equal to 1 the word concentration is written in black colour You can use the small buttons to set the concentration of the element i to 1 minus the sum of concentrations of all other elements c 1 us cj The areal density is in 10 atoms cm Whether concentration or areal density of an element is used is determined by the Concentration Areal density radio button see below Isotopes These buttons can be used to change the concentrations of isotopes of that element in the actual layer You will need this only if this element does not have the natural composition of isotopes You can create for example a layer of enriched 13C on top of 12C or the like The sum of concentrations of all isotopes of one element must be equal to 1 Note The Isotopes check box in the Setup Calculation menu must be checked to manipulate individual isotopes Concentration Areal density This radio button allows to select if amounts of individual elements are entered as
196. teger Description Selects the electronic energy loss straggling model Allowed values are 1 Bohr s theory 2 Chu s theory See subsection 4 8 2 for more details about straggling models Related Properties and Methods Calc Straggling 176 SubstrateRoughnessDimension Get Set Property SubstrateRoughnessDimension Integer Description Dimensionality of substrate roughness Allowed values are 0 Dimension 2 0 1 Dimension 2 5 177 A OLE automation reference ZBStopping Get Set Property ZBStopping Boolean Description Selects Ziegler Biersack or Andersen Ziegler stopping If ZBStopping is true Ziegler Biersack stopping is used while Andersen Ziegler is selected if ZBStopping is set to false See subsection 3 6 3 for more details about stopping power data Related Properties and Methods Calc HighEnergyStopping 174 A 5 Simnra Target The Simnra Target object represents the target with all layers and elements A 5 1 Properties ElementAmount Get Set Property ElementAmount lay el Integer Double Description Amount of element number el in layer number lay 10 atoms cm Parameters lay Number of the layer with 1 X lay NumberOfLayers el Number of the element with 1 lt el lt NumberOfElements lay Related Properties and Methods 178 A OLE automation reference Target ElementConcentration 179 Target LayerThickness 181 ElementConcentration Get Set Property ElementCon
197. ten in Borland Delphi and uses only automation compatible data types The data types used by Delphi the corresponding types in Microsoft s Interface Definition Language IDL and the corresponding types used in Variants are summarized below Delphi type IDL type Variant type Description Boolean VARIANT BOOL VT BOOL True 1 False 0 Double double VT R8 8 byte real Integer long VT I4 4 byte signed integer WideString BSTR VT_BSTR binary string A 2 Simnra App The Simnra App object represents the application itself A 2 1 Properties Active Get Property Active Boolean Description Specifies whether SIMNRA is active and has focus Active is True while SIMNRA is active and False if it is not SIMNRA is active if it has focus and becomes inactive when a window from a different application is about to become activated Active is readonly Related Properties and Methods App BringToFront 156 App Minimize 160 App Restore 162 CalculatingSpectrum Get Property CalculatingSpectrum Boolean Description 151 A OLE automation reference Indicates if a spectrum is currently being calculated CalculatingSpectrum is True while a spectrum is being calculated by clicking Calculate Spectrum or Calculate Spectrum Fast and False after the calculation has been finished CalculatingSpec trum can be used for synchronizing SIMNRA with OLE clients CalculatingSpec trum is readonly Related Properties and Methods
198. tepwidth can be increased to several 100 keV The stepwidth of incident ions affects the time T necessary to perform a calculation strongly T depends on the stepwidth of the incoming ion AE roughly as T x 1 AE Decreasing the stepwidth by a factor of two will roughly double the computing time Note 1 The stepwidth of incident ions is an important parameter for the accuracy of a simulation The accuracy may be increased if a small Fixed stepwidth is used instead of Automatic step width control at the cost of higher computing times Note 2 If the backscattering cross section contains narrow resonances a Fixed stepwidth of incident ions with a step width smaller than the width of the resonances gives best results Automatic stepwidth control can be used together with narrow resonances in SIMNRA 5 02 and higher but may result in slightly too broad structures in the spectrum Note 3 If a Fixed stepwidth of incident ions is used and the stepwidth is too high unwanted oscillations or steps in the simulated spectra may occur This is due to rounding errors in the routine which calculates the contents of each channel If these oscillations occur you have to decrease the stepwidth of incident ions These problems should never occur with automatic stepwidth control The program always uses a stepwidth which is small enough Stepwidth outgoing ions Stepwidth of outgoing particles used in the calculation See chapter 4 for details Automatic or F
199. ter accuracy 14N3Hep12 90 33 N14He3p1 2t90 r33 5 10 Better accuracy 14N3Hep34 135 0133 N14He3p3 4t135 r33 5 10 Better accuracy 14N3Hep34 90 133 N14He3p3 4t90 r33 5 10 Better accuracy CRSDA DAT various see text 5 81 Better accuracy Table 3 7 Replacement of cross section data files 3 8 1 Replacement of cross section data files Throughout the long history of SIMNRA cross section data files were renamed reformated from RTR to R33 or replaced by more accurate data To provide backward compatibility the file REPLACE LST is used It lists the original cross section data file which has been deleted or renamed and the file it has been replaced with If an NRA file is opened which references a renamed or replaced cross section data file this file is automatically replaced and the new data are used for all calculations The format of the file REPLACE LST is as follows OldFile NewFile TagNr OldFile is the name of the renamed or replaced file and NewFile the name of the file it has been replaced with TagNr is an integer number which is used only together with the file CRSDA DAT for any other file 0 should be used The replaced files the SIMNRA version of the replacement and the reasons for replacement are listed in Table 3 7 The file CRSDA DAT developed at the IPP Garching between 1985 and 1995 and containing polynomial fit coefficients to various cross section data was deleted in SIMNRA 5 81 The accuracy of the fits was poor an
200. tering geometry etc and spectral data Note 1 RUMP stores the description of the sample and the absorber foil in sample description files LCM You can read sample description files with RUMP Read Sample Description File Note 2 The RBS file may contain only one experimental spectrum Compression level 3 zero compression is not implemented See section 3 14 for more details RUMP Read Sample Description File This menu item allows to read a sample description file produced by RUMP or the IBA data furnace NDE The default file extension of sample description files is LCM Note 1 RUMP stores the description of the sample and the absorber foil in sample de scription files LCM The experimental parameters Type of incident particles incident energy scattering geometry etc and spectral data are stored in files with extension RBS You can read RBS files with RUMP Read RBS File Note 2 SIMNRA supports only a subset of the RUMP sample description commands Especially the RUMP commands Equation Species and Fuzz are not supported If your sample description file contains these commands they will be neglected and a warning will be shown See section 3 14 for more details RUMP Write Sample Description File This menu item allows to store the structure of the target and the absorber foil in a sample description file in RUMP format The default file extension is LCM These files can be read by RUMP or the IBA data f
201. th together with uncertainties in the calculation of the plural scattering background are the reason for this small discrepancy Additionally it should be kept in mind that the used model of inclined line segments see Figure 4 15 b is only an approximation to physical reality and the real surface has an additional fine structure The influence of the different roughnesses on the shape of the RBS spectrum is shown in more detail in Figure 4 25 The experimental data black dots and the solid line in the top and bottom figures are the same as in Figure 4 24 The substrate roughness is kept constant in Figure 4 25 top and the roughness of the W layer is varied from smooth to 0 6 um The roughness of the W layer influences mainly the low energy edge of the W peak best fit is obtained for o 0 3 um The bottom part shows the influence of the carbon substrate roughness for constant W layer roughness Substrate roughness influences mainly the low energy tail below the W peak while the low energy edge of the W peak is less affected by substrate roughness Best fit is obtained for about 20 FWHM Due to the different effects of the 123 4 Physics two roughnesses on the shape of RBS spectra the two roughnesses can be easily distinguished 124 4 Physics e Experimental Smooth layer 400 Rough layer c 0 3 um Rough layer c 0 6 um 300 200 Counts o e Experimental Substrate roughness 10 400 Substrate roughness 20 S
202. that all of the data values are contained in the file and have been read Data entries must be arranged in order of increasing energy or angle Duplicate energy or angle values are not allowed the cross section must be single valued 210 Bibliography 1 2 3 4 5 6 7 La 8 9 La 10 11 12 13 14 15 N P Barradas M Mayer and M Thompson Nucl Instr Meth B 268 2010 1824 7 EG amp G ORTEC Model 672 spectroscopy amplifier operating manual Tech rep EG amp G ORTEC Oak Ridge U S A 18 H H Andersen and J E Ziegler Hydrogen Stopping Powers and Ranges in All Elements vol 3 of The Stopping and Ranges of Ions in Matter Pergamon Press New York 1977 22 24 85 88 J E Ziegler Helium Stopping Powers and Ranges in All Elements vol 4 of The Stopping and Ranges of Ions in Matter Pergamon Press New York 1977 22 86 J E Ziegler J P Biersack and U Littmark The Stopping and Range of Ions in Solids vol 1 of The Stopping and Ranges of Ions in Matter Pergamon Press New York 1985 22 87 88 89 97 J E Ziegler private communication 1997 22 G Konac S Kalbitzer Ch Klatt D Niemann and R Stoll Nucl Instr Meth B 136 138 1998 159 22 90 G Konac Ch Klatt and S Kalbitzer Nucl Instr Meth B 146 1998 106 22 90 J R Tesmer and M Nastasi Eds Handbook of Modern Ion Beam Materials Analysis first ed Materials Research Society Pittsb
203. the cross sections are Rutherford up to high energies However this approximation may result in incorrect spectra if non Rutherford scattering from light elements is important SIMNRA will issue a warning message if dual scattering is used with non Rutherford cross sections 21 3 Using SIMNRA Note 2 SIMNRA calculates dual scattering only for incident ions and not for recoils or reaction products of nuclear reactions Additional scattering in a foil in front of the detector if any is neglected Note 3 If Dual Scattering is checked then Straggling must be checked too SIMNRA will check Straggling automatically if Dual Scattering is checked As long as Dual Scattering is checked Straggling cannot be unchecked Stopping power data The selection of stopping power data has a large influence on the shape of the simulated spectra SIMNRA can use different sets of electronic stopping power data for the stopping of light and heavy ions in all elements Andersen Ziegler Electronic stopping power data by Andersen and Ziegler 3 4 5 Note If the Andersen Ziegler stopping power data are used for incident hydrogen isotopes or heavy ions near 1 MeV amu artificial steps or kinks may appear in the simulated spectra This is due to a jump of the stopping power at 1 MeV amu See the description of the High energy stopping switch for a work around Ziegler Biersack Electronic stopping power data by Ziegler Biersack and Littmark 5
204. the file including path Related Properties and Methods Target ReadTarget 186 A 6 Simnra Fit The Simnra Fit object represents the fit parameters i e what to fit number of fit regions maximum number of iterations etc You have to adjust the fit parameters in the Simnra Fit object first before the fit can be performed with the App FitSpectrum 159 method 186 A OLE automation reference A 6 1 Properties Accuracy Get Set Property Accuracy Double Default Value 0 01 Description Desired accuracy of the fit see subsection 3 9 1 Fitting will be performed until the desired accuracy is obtained or the maximum number of iterations is reached Related Properties and Methods Fit Maxlterations 190 Chi2Evaluation Get Set Property Chi2Evaluation Integer Default Value 0 Description Determines how xy is determined see page 50 for details Allowed values are 0 Channels 1 Integrals EnergyCalibration Get Set Property EnergyCalibration Boolean Default Value false 187 A OLE automation reference Description Specifies if the energy calibration offset and linear term is fitted The energy calibration is fitted if EnergyCalibration is true LayerComposition Get Set Property LayerComposition Boolean Default Value false Description Specifies if the composition and thickness of a target layer is fitted The number of the layer is specified by the LayerNr property The com
205. the nuclear charges by the electron shells surrounding both nuclei see section 4 4 None Rutherford cross section without screening see Equation 4 15 This option should be used only for test purposes Ecuyer Screening function according to LEcuyer see Equation 4 16 The LEcuyer screening function is only reasonable for RBS with backscattering angles 0 gt 90 and should be used only for test purposes The Andersen screening function is generally a better choice Note If L Ecuyer is selected for recoils this selection is ignored and replaced by Andersen Andersen Screening function according to Andersen see Equation 4 17 Andersen s screening function is generally the best choice and the program default Options tab Element Spectra If checked individual spectra for each element in the target are calculated and plotted If unchecked only the total spectrum is calculated and plotted Default is unchecked 23 3 Using SIMNRA Figure 3 7 Examples of ion trajectories with one two and three scattering events Incident ion Andersen Ziegler Ziegler Biersack keV amu keV amu Hydrogen H D T 1 100000 1 100000 Helium CHe He 0 25 2500 1 100000 Heavy ions 1 100000 1 100000 Table 3 2 Energy ranges in which the different stopping power formulas are valid High energy electronic stopping formula for energies gt 2 5 MeV amu from 3 not implemented Isotope Sp
206. thods Target LayerRougness 181 HasSubstrateRoughness Get Set Property HasSubstrateRoughness Boolean Description Returns true if the substrate is rough and false if substrate roughness is switched off i e the substrate is smooth Substrate roughness can be switched off by setting HasSubstrateRoughness to false If HasSubstrateRoughness is set to true Lorentzian substrate roughness is selected The FWHM of the roughness is specified by Target SubstrateRoughness If HasSubstrateRoughness is false then Target SubstrateRoughness is ignored Note This function is obsolete and maintained only for backward compatibility to earlier versions of SIMNRA Use Target SubstrateRoughnessDistribution instead Related Properties and Methods Target SubstrateRougness 182 Target SubstrateRoughnessDistribution 182 180 A OLE automation reference LayerRoughness Get Set Property LayerRoughness lay Integer Double Description FWHM of the roughness of layer number lay 10 atoms cm Tar get HasLayerRoughness lay must be true otherwise LayerRoughness has no effect Parameters lay Number of the layer with 1 X lay NumberOfLayers Related Properties and Methods Target HasLayerRougness 180 LayerThickness Get Set Property LayerThickness lay Integer Double Description Thickness of layer number lay 10 atoms cm Parameters lay Number of the layer with 1 X lay NumberOfLayers NumberOfEle
207. thout compression the file size arguments are not compelling and insisting on following the original specification will involve disrupting several existing readers as well as introducing 205 B The R33 cross section file format confusion through the existence of two families of R33 files since copies of the erroneous files will probably lie around for years in different places So the new specification legalises the previous erroneous usage B 2 1 Syntax of an R33 Entry The syntax for the list of legal keywords and the associated data is Keyword Mx O R Default lt data type gt Note Additional notes and guidelines concerning use of the entry Data type may be string an arbitrary series of ascii characters n integer a series of ascii characters without decimal point representing a signed integer number r real a series of ascii characters that represent a signed real number Format is fairly flexible but only decimal points and NOT decimal commas are accepted Any format that can be read in a Borland Pascal readln r statement is acceptable B 2 2 List of legal entries Comment R CNone String Note An unlimited number of ascii characters including single CR LF sequences but terminating by a double CR LF sequence There is no requirement to embed CR LF sequences within the Comment however it is recommended to place CR LF sequences at convenient places at least every 80 characters so that if the file
208. ti elemental targets with stopping thus yielding the angular spread 107 4 Physics distribution for realistic cases They also proposed an approximation how to obtain the energy spread distribution from the angular spread distribution via the chord angle Angular spread and energy spread are strongly correlated 54 Section 4 This correlation is taken into account in the calculation of the energy of backscattered or recoiled particles The Szilagyi Amsel theory was initially implemented in the DEPTH code 39 62 which is primarily intended for depth resolution calculations SIMNRA contains an independent implementation of the Szilagyi Amsel theory A comparison of DEPTH SIMNRA Monte Carlo calculations in binary collision approximation and molecular dynamics calculations can be found in 63 When using multiple scattering calculations it should be kept in mind that SIMNRA uses the following approximations 1 Multiple scattering energy spread distributions are approximated by Gaussian functions In reality these distributions have stronger wings which are underestimated by SIMNRA 2 Multiple scattering distributions are assumed to be symmetric around a mean value This is never fulfilled exactly and most strongly violated at normal incidence and at grazing incidence 3 Energy transfer to target atoms i e nuclear stopping and straggling results in low energy tails These tails are neglected 4 9 3 Plural large angle
209. tion Method of y evaluation EnergyCalibration Specifies if the energy calibration is fitted LayerComposition Specifies if the composition of a layer is fitted LayerNr Specifies which layer is fitted 149 A OLE automation reference LayerRoughness Specifies if the roughness of a layer is fitted LayerThickness Specifies if the thickness of a layer is fitted Maxlterations Maximum number of fit iterations NumberOfRegions Number of different fit regions ParticlesSr Specifies if the number of incident particles times solid angle is fitted RegionMaxChannel Upper channels of fit regions RegionMinChannel Lower channels of fit regions Simnra Spectrum AutoScale Specifies if the plot is scaled automatically BottomAxisMax Bottom axis maximum BottomAxisMin Bottom axis minimum Data Data in a specific channel Integrate Integrates a spectrum LeftAxisMax Left axis maximum LeftAxisMin Left axis minimum NumberOfChannels Number of channels in a spectrum Simnra Stopping EnergylossInLayer Energy loss in a target or foil layer keV StoppingInElement Stopping power in an element keV 10 atoms cm StoppingInLayer Stopping power in a target or foil layer keV 10 atoms cm StragglingInLayer FWHM of energy loss straggling in a target or foil layer keV 150 A OLE automation reference A 1 Data types SIMNRA is writ
210. tion must be energy and the value of theta has no meaning Nevertheless it is suggested that a valid real number be given for theta so that reading routines don t have to cater for non numerical values for theta such as Theta irrelevant O 1 0 0 0 0 0 0 0 lt rrrr gt Note Scale conversion factors and associated errors common to all the energy or angle data See original R33 publication in Appendix 1 for discussion M2 R 0 n M2 R O Note two methods are allowed for representing the data The first corresponds to the original R33 specification The data immediately following the Nvalues entry consists of the cross section data one point per line and each point represented by four values X dX Y dY energy or angle energy or angle random error sigma sigma random error The data ends after Nvalues lines of data Alternatively and recommended the data may be bracketed by Data and Enddata entries An entry of Nvalues 0 is equivalent to a Data entry The data immediately follow the Data entry one point per line as for the Nvalues option and the file terminates with the end of the file or with the optional EndData entry Nvalues is maintained for backward compatibility but in practice most routines will simply read and count the number of lines read until the end of the file or an EndData entry is reached so this is the preferred option The use of the Enddata entry simply allows a check
211. tionally may perform more than one scattering event with large scattering angle see Figure 4 12 middle and right before they are scattered towards the detector This has been called plural scattering Multiple scattering has been reviewed by Szil gyi et al 39 and Amsel et al 54 Multiple scattering results in an angular spread of the particles and therefore in a spread of path lengths Due to the path length differences we get an energy spread of the particles in a given depth Plural scattering with 2 3 4 scattering events is responsible for the background behind the low energy edge of high Z elements on top of low Z elements and the steeper increase of the spectra towards low energies than calculated with single scattering 55 56 57 58 59 SIMNRA is able to calculate dual scattering i e all particle trajectories with two scattering events 4 9 2 Multiple small angle scattering Angular and lateral spread due to multiple collisions with small deflection angles was treated analytically and numerically by Sigmund et al 60 61 for realistic screened interaction potentials of the Thomas Fermi and Lenz Jensen type However their theory is only valid for 1 Single elemental targets 2 The stopping of ions is neglected Due to these two assumptions the original Sigmund theory is only of limited practical use Szilagyi et al 39 and Amsel et al 54 have proposed a method how to extend the original Sigmund theory to mul
212. topes have been taken from the recommended values of isotopic abundances in 20 Isotopic masses and abundances are stored in the file ATOMDATA DAT This file contains also the data of some isotopes which do not occur naturally but may be created in nuclear reactions and are necessary for kinematic calculations 73 4 Physics 4 2 Scattering kinematics 4 2 1 Elastic scattering Energy of backscattered projectiles The energy E of a backscattered projectile with incident energy Ey and mass M after scattering is given in the laboratory system by M2 M3 2 1 2 E E 4 cos0 sin 0 4 4 1 0 M Mai M 0 is the scattering angle and M the mass of the target nucleus initially at rest For M4 lt M3 only the plus sign in Equation 4 4 applies If M4 gt M then Equation 4 4 has two solutions and the maximum possible scattering angle Omax is given by M2 Onax arcsin 4 5 M The second solution for M gt M is obtained because different impact parameters d result in the same scattering angle 0 Consider for example the scattering angle 0 0 This angle is obtained for a head on collision with d 0 but also for very large impact parameters d 4 oo SIMNRA version 3 50 and higher uses both solutions of Equation 4 4 if kinematically possible Earlier versions of SIMNRA used Equation 4 4 only with the plus sign the solution with the minus sign was neglected Energy of recoils The energy E of
213. tor type is Solid state in the Setup Experiment More Options Detector type menu Detector Resolution is not used for other types of detectors such as time of flight detectors Note 2 SIMNRA uses a constant energy independent detector resolution for each ion species This is more or less true for light ions protons and He but for heavy ions the detector resolution depends on the particle energy Energy dependent solid state detector resolutions are not yet implemented in SIMNRA Energy spread of incident beam Usually the incident ion beam is not monoenergetic but has an energy distribution SIMNRA assumes a gaussian energy distribution of the incident beam with a full width at half maximum which can be entered in the Energy spread of incident beam field If this field is set to 0 0 SIMNRA assumes a monoenergetic incident beam The File menu allows to save experimental setups to disk and read experimental setups from disk All information contained in the Setup Experiment form the Detector geometry form all energy calibrations and all detector resolutions are saved The NRA data file format is used for saving Save as Default The current experimental setup is stored as startup default for SIMNRA in the file DEFAULT SETUPNRA Save Setup as Save the current experimental setup to file 13 3 Using SIMNRA Figure 3 3 Geometry of a scattering experiment Incident angle a exit angle 6 and scattering angle 0 Rea
214. tted parameters are accurate To obtain realistic error bars all parameters should be fitted in one step A quantitative measure for the goodness of fit of the assumed model can be obtained from the value of Y uw See 12 Chapter 14 1 or any good textbook about statistics for more information 3 9 2 Subtracting pile up Allows to subtract the pile up contribution from experimental data The pile up is calculated iteratively from experimental data and not from simulated data as is the case if you check 51 3 Using SIMNRA Figure 3 11 Ay 1 contour near the y minimum black dot for two fit parameters a and a Aa and Aa are the fit errors for a and a if fitted simultaneously Aaj the error for a if only a is fitted Calculate pile up in the Setup Experiment More Options Live Time and Pile up form see section 3 6 2 You can use this menu item to subtract pile up from any type of spectral data including RBS or ERDA spectra X ray spectra for example PIXE or y ray spectra The parameters Real time Live time Pulse rise time Fudge time parameter Pile up rejector and Pile up rejector pair resolution time are described in section 3 6 2 see there Number of iterations The pile up contribution is calculated iteratively from the data Number of iterations specifies the number of iterations In most cases 2 3 iterations are sufficient Calculate pile up Calculates the pile up contribution from the experim
215. ttp ibaserver physics isu edu sigmabase newuser html for more information about SigmaBase The stopping power data and subroutines for Ziegler Biersack stopping have been taken from Zieglers SRIM 97 program but were translated from BASIC to PASCAL The routines for reading RUMP s RBS file format were obtained from Peter Revesz Cornell University USA They were translated from C to PASCAL The graphics subsystem for SIMNRA versions prior to 4 5 was developed by Achim von Keudell Max Planck Institut f r Plasmaphysik Garching Germany Valuable input and bug reports were obtained from Joachim Roth Hans Maier Karl Krieger Thomas K ck and Karl Ertl Max Planck Institut f r Plasmaphysik Garching Germany J rg R hrich and Swen Lindner Hahn Meitner Institut Berlin Germany G nther Dollinger Technische Universit t M nchen Germany Peter Revesz Cornell University USA Andreas Gabrielsen Norway Caroline Raepsaet Centre d tudes de Saclay France and Alexander Gurbich Institute of Physics and Power Engineering Obninsk Russia Additional cross section data were obtained from Iva Bogdanovi Radovi Rudjer Bo kovi Institute Zagreb Croatia B Diaz Herrera Max Planck Institut f r Plasmaphysik Garching Germany LN Kim Max Planck Institut f r Plasmaphysik Garching Germany Beata Tyburska Max Planck Institut f r Plasmaphysik Garching Germany Herbert Kulinski Max Planck Institut f r Plasmaphysik
216. ubstrate roughness 30 300 200 400 600 800 Channel Figure 4 25 Same experimental data as in Figure 4 24 compared to simulation calculations with different roughness parameters Top Calculations for a rough carbon substrate FWHM 20 and differ ent W layer roughnesses characterized by a Gamma distribution with standard deviation o Bottom Calculations for a rough W layer o 0 3 um and different substrate roughnesses characterized by a Lorentz distribution of tilt angles with different FWHM s Mean W layer thickness 3 5 um plural scattering included 125 4 Physics 4 11 Live time and pile up Nuclear spectroscopy systems are unavoidable sources of spectral distortions due to the finite pulse widths of the generated electronic signals and the paralyzable nature of the electronic system which is not able to accept a second pulse while the previous is still being processed Due to the finite pulse width there is always a probability of pulses to overlap resulting in pulse pile up while the paralyzation of the system results in dead time losses of incident pulses These distortions of the spectra can be minimized by decreasing the incident count rate by decreasing the incident beam current or the detector solid angle but they are usually clearly visible at higher count rates These are often desirable due to the shorter measuring times This section describes how SIMNRA can take these effects into account in simulatio
217. ulse rise time T can be derived from the Gaussian shaping time Tg7 from 2 T 2 2X Tgr 3 2 The pulse rise time can be measured accurately with an oscilloscope at the amplifier output However as SIMNRA approximates the true pulse shape with a parabola see subsection 4 11 2 Figure 4 28 and Figure 4 29 it is advantageous to use a slightly smaller value for T than obtained from Equation 3 2 see Figure 3 6 and Table 3 1 If Canberra s CAM files are used the pulse rise time is computed from the values for the Gaussian shaping time DSP rise time and DSP flat top duration stored in the file according to Table 3 1 18 3 Using SIMNRA Time Figure 3 5 Schematic representation of an amplified pulse with Gaussian shaping Ee is the pulse rise time 1 5L True signal i Parabolic approximation EO WT AN Ee T 1 5xr 2 p ST o T 1 9X t B AOL ff ay a E 905 E 2 N 0 0 3 2 1 0 1 2 3 4 Time us Figure 3 6 Selection of the pulse rise time T for a Gaussian pulse True pulse from an Ortec 672 spectroscopy amplifier shaping time Tgy 1 us SIMNRA approximates the Gaussian pulse shape with a parabola The figure shows parabolas with rise times T equal to 1 5 1 9 and 2 2 times the Gaussian shaping time The parabola with T 1 9 x Tgy usually gives the best approximation to the true pulse shape 19 3 Using SIMNRA Device Pulse rise time Tp
218. umber is the deepest layer Backscattered particles first penetrate the foil layer with the highest number the foil layer 1 is in front of the detector 31 3 Using SIMNRA 1 0 m f Layer 1 Layer 2 Layer 3 Layer 4 c 08 J 2 s Depth H C S 0 6 a 0 0 0 0 0 g HI 0 0 2 0 8 O o4 100 0 2 0 8 100 0 4 0 6 200 0 4 0 6 0 2 200 0 3 0 7 de b t 0 0 0 50 100 150 200 250 300 350 400 300 0 1 0 9 400 0 1 0 9 Depth DO Atoms cm Figure 3 9 Left Example for a depth profile file The target consists of 4 layers The first line contains the names of the elements H and C The depth scale is in 101 atoms cm the other columns contain the concentrations of the individual elements in the layers The columns are separated by tabs Right Graphical representation of the depth profile Has substrate roughness Check if the layers are on top of a rough substrate A rough substrate is described by a distribution of incident and exit angles and has no other influence Only one substrate can exist for all layers i e the substrate parameters are identical for all layers Substrate roughness is not available for foils The distribution of incident and exit angles is divided into M steps The step number M can be adjusted by the Number of angular steps in the Setup Calculation menu see subsection 3 6 3 FWHM of substrate roughness SIMNRA assumes a Lorentz distribution of an
219. ure 4 16 The carbon substrate was already rough with a standard deviation o 18 2 nm The roughness of the Ni film on the substrate was Gc y 26 5 nm This roughness is made up by the roughness of the carbon substrate plus the roughness of the Ni film oyi By assuming the two roughnesses to be independent i e TEINI oe Ex the roughness of the Ni film alone is about 19 3 nm in good agreement with the result from He backscattering of 23 nm The energy spectrum of 2 0 MeV He backscattered from a rough oxidised aluminum film on polycrystalline carbon is shown in Figure 4 19 The carbon substrate was well polished and had a mean roughness 25 nm 76 The film was exposed for about 8 months as erosion monitor at the vessel wall of the nuclear fusion tokamak experiment JET 77 76 the wall temperature was about 300 C The initial Al layer thickness was 3 16 x 101 atoms cm 525 nm but 115 4 Physics 300 250 200 150 Counts 100 50 Channel Figure 4 19 2 MeV He backscattered at 165 from a rough oxidised aluminum film on carbon The film was used as long term sample in the tokamak JET and was strongly eroded by plasma impact Additionally some Ni was deposited from the plasma Dots Experimental data Solid line Simulation with a mean film thickness of 1 11 x 101 atoms cm and roughness o 1 06 x 101 atoms cm Film composition 68 Al 30 O 2 Ni decreased due to sputtering by bombardment with e
220. urgh Pennsylvania 1995 34 78 J A Nelder and R Mead Computer Journal 7 1965 308 49 M S Caceci and WP Cacheris Byte 5 1984 340 49 WH Press B P Flannery S A Teukolsky and WT Vetterling Numerical Recipes Cambridge University Press Cambridge New York 1988 49 51 82 83 L Cliche S C Gujrathi and L A Hamel Nucl Instr Meth B 45 1990 270 69 W H sler and R Darji Nucl Instr Meth B 85 1994 602 69 E Steinbauer P Bauer M Geretschl ger G Bortels J P Biersack and P Burger Nucl Instr Meth B 85 1994 642 69 211 Bibliography 16 M J E Healy M Torres and J D Painter Nucl Instr Meth B 249 2006 789 70 17 R Doolittle Nucl Instr Meth B 9 1985 344 71 82 111 18 R Doolittle Nucl Instr Meth B 15 1986 227 71 111 19 G Audi and A H Wapstra Nucl Phys A595 1995 409 73 20 P De Bievre and PD P Tylor Int J Mass Spectrom Ion Phys 123 1993 149 73 21 J LEcuyer J A Davies and N Matsunami Nucl Instr Meth 160 1979 337 78 22 M Hautala and M Luomaj rvi Rad Effects 45 1980 159 78 23 H H Andersen E Besenbacher P Loftager and W M ller Phys Rev A21 6 1980 1891 78 24 S R Lee and R R Hart Nucl Instr Meth B 79 1993 463 78 25 M Bozoian K M Hubbard and M Nastasi Nucl Instr Meth B 51 1990 311 80 26 M Bozoian Nucl Instr Meth B 58 1991 127 80 27 M Bozoian Nucl Instr Meth B 82 1993 6
221. urnace NDE Note SIMNRA allows to define a correction factor for the stopping power of each layer for each ion species The correction factors are not stored in the sample description file Print This menu item will print all parameters of the calculation and plot the experi mental and simulated curves See also the print preferences on the Options Preferences tab 3 Using SIMNRA This line may contain any comment lt CR gt lt LF gt This line may contain any comment as well lt CR gt lt LF gt Channel Counts lt CR gt lt LF gt 1 1000 lt CR gt lt LF gt 2 1000 0 lt CR gt lt LF gt 3 1 0E3 lt CR gt lt LF gt 4 1 0E3 lt CR gt lt LF gt lt EDF gt Figure 3 2 Example for a valid data file which can be imported with File Read Data ASCII The first three lines will be ignored by the program The channel number must be an integer number counts may be integer or floating point numbers Note 1 SIMNRA is not intended to produce high quality graphics If you want to obtain these you should use a graphics program such as Excel or Origin You can exchange data between SIMNRA and any graphics program by file with File Write Data and via the clipboard with Edit Copy Data Exit Terminates the program 10 3 Using SIMNRA 3 5 Edit menu Copy Data Copies experimental and simulated data in ASCII format to the clipboard They can be pasted into any spreadsheet program The format of the data in the cl
222. ves the pile up signal between the two peaks see Figure 4 27 is eliminated Fast model Major disadvantage of the Accurate model section 4 11 2 is its long computing time A much faster but also less accurate model for pile up calculations was proposed by Jeynes 84 In 132 4 Physics 100000 10000 1000 c 3 o O 100 10 PUR off PUR on 1 300 400 500 600 700 Channel Figure 4 30 Effect of a pile up rejector PUR on pile up from a single peak The pile up with a pile up rejector switched off and on is shown Pulse rise time 1 us pair resolution time 0 3 us The curve with PUR off is the same as in Figure 4 27 133 4 Physics the Jeynes model which is selected by the Fast pile up model in SIMNRA two pulses i and j always pile up to a pulse k with k i j Le in the Jeynes model two pulses always arrive simultaneously and T fi j k TES f ANE O otherwise where Ty is a fudge factor without physical meaning and the dimension of a time The losses L and gains G in each channel k then can be written as Ly 2ANn k 1 Gk SAX nini i 1 with a fudge factor A T A Lee Tneal The content of each channel of the spectrum with pile up n U is then given by a dni 4 95 k 1 n 2A4Nn A nini 4 96 i 1 with the channel content of the undistorted spectrum without pile up ng The factor A or Tei can be freely adjusted to obtain best fit to a measured spectrum The Ac
223. way that Ac EE 4 68 Hz where 6 is the desired accuracy SIMNRA uses a default of 6 196 An estimate of the accuracy of straggling calculations can be obtained with the program VIEWNRA An example for the accuracy of straggling calculations and the error estimate is shown in Figure 4 10 The error of the straggling calculation is obtained by comparison to a calculation with very small fixed step width The error estimate based on Equation 4 67 gives the correct sign and magnitude of the real error 100 4 Physics Energy keV 700 750 800 850 900 950 1000 e Experimental 6000 4000 Counts 2000 Li 500 7i 600 Channel Energy keV 740 750 760 770 780 790 800 6000 4000 2000 0 em 540 560 580 600 Channel Figure 4 9 Measured and simulated spectra using Bohr and Chu straggling of 1 0 MeV He ions incident on 100 nm Au on Si scattering angle 165 Bottom Magnification of the low energy gold edge 101 4 Physics 2000 1500 1000 500 Energy at surface keV 20r Straggling at surface keV FWHM Error i EES Error estimate E Ku T o o a Error 0 0 0 5 0 2000 4000 6000 8000 Depth DOT atoms cm Figure 4 10 Energy and energy loss straggling of backscattered He ions at the target surface in Au Incident angle a 0 exit angle 6 15 scattering angle O 165 Yang straggling Top Ener
224. ws to enter SiO as Si 1 O 2 SIMNRA will convert this to Si 0 33333 O 0 66666 As units for thickness are possible CM2 M CM2 A NM If A for or NM for nm are used SIMNRA will use the weighted atomic densities of all elements in the layer to convert or nm to 10 atoms cm It is highly recommended to use the units CM2 or M CM2 instead Table 3 9 RUMP sample description commands which are supported by SIMNRA 59 3 Using SIMNRA RBS Files SIMNRA can read RUMP s RBS file format version 1 1 from 8 94 with the following limitations 1 Data compression level 3 zero compressed is not implemented Levels 0 2 uncom pressed real uncompressed integer differential integer are fully implemented 2 Each RBS file may contain only one spectrum Record type 20h is allowed but may contain only one row 3 Only one record 120h RBS spectrum type or 121h FRES spectrum type may be present Le simultaneous RBS and FRES ERD are not allowed 4 Record types 01h printed comments 02h unprinted comments 101h identifier for the data set 102h MCA information and 103h collection date time are recognized but ignored 5 Record type 111h accelerator parameters Beam current is ignored by SIMNRA and pile up is not calculated 6 Record type 112h data collection parameters Starting channel of data is rounded from real to integer This may result in differences of 0 5 channels between RUMP and SIMNRA if a non
225. xml files zlib1 dll ATOM ATOMDATA DAT atomic data STOP STOPH DAT electronic stopping power data Andersen Ziegler STOPHE DAT LCORRHI DAT SCOEE95A electronic stopping power data Ziegler Biersack SCOEE95B CRSEC CHU_CORR DAT SRIM2003 x y z dat ZB x y z dat R33 Chu correction data to Bohr straggling Stopping power data files with SRIM stopping Stopping power data files with Ziegler Biersack stopping b cross section data SAMPLES NRA RTR REPLACE LST Replacement of cross section data files see subsec tion 3 8 1 DLL DLL dynamic link libraries used by SIMNRA examples LAYERS LAY predefined materials mylar stainless steel DEFAULT SETUBNRA default experimental setup CALC NRA default parameters for calculations USERDLL SAMPLE DPR Code examples in Pascal for user supplied dynamic link libraries see section 3 15 XML IDF_Template xml XML template file for xnra files These files are only created whenever a calculation with SRIM stopping is performed The number of these files depends on the number of already performed calculations These files are only created whenever a calculation with Ziegler Biersack stopping is performed The number of these files depends on the number of already performed calculations Table 2 1 Directory structure and files used by SIMNRA 3 Using SIMNRA 3 1 Data input forms Input
226. y 1985 10 a a O 165 9600 10500 AO CA85B RTR Caskey 1985 10 a a O 165 10320 10700 AO CA85C RTR Caskey 1985 10 a a O 165 10650 11100 AO CA85D RTR Caskey 1985 10 a a O 165 11050 11600 AO CA85E RTR Caskey 1985 10 a a O 165 11500 12500 AO CAB5ERTR Caskey 1985 10 a a O 165 12150 12750 AO CA85G RTR Caskey 1985 10 a a O 165 12500 13500 AO CA85H RTR Caskey 1985 O a a o 165 9150 12750 AO CASSLRTR Caskey 1985 10 a a O 165 7 5000 12500 AO JO69A RTR John 1969 O a a O 170 2000 9000 AO CH93A RTR Cheng 1993 10 a a O 170 1770 5000 AO LE9OA RTR Leavitt 1990 O a a 0 160 2400 3500 AO _PO64A RTR Powers 1964 F a a F 165 1500 5000 AF CH93A RTR Cheng 1993 19E a a F 170 1500 2300 AF_CS84A RTR Cseh 1984 PE a 0 2F 170 2300 3700 AF_CS84B RTR Cseh 1984 PE a 0 PF 170 1500 4000 AF CS84C RTR Cseh 1984 Ne a a Ne 167 3 2400 3200 ANEGO54A RTR Goldberg 1954 Ne a a Ne 167 3 3200 4000 ANEGOS4B RTR_ Goldberg 1954 Ne a a Ne 167 3 2400 4000 ANEGO54C RTR Goldberg 1954 Na a a Na 165 2000 6000 ANACH91A RTR Cheng 1991 Mg a a Mg 165 2000 9000 AMGCH93A RTR Cheng 1993 Mg a a Mg 162 5 3150 3900 AMGCS82A RTR Cseh 1982 Mg a a Mg 162 5 4200 4900 AMGCS82B RTR Cseh 1982 24Mg a a Mg 164 3150 3900 AMGKA52A RTR Kaufmann 1952 4Mg a 0 Mg 165 5900 6250 AMGIK79A RTR Ikossi 1979 Mg a a Mg 165 6080 6140 AMGIK79B RTR Ikossi 1979 Si a a Si 170 2000 6000 AS
227. y read Data Input parameter Pointer to an array of 32 bit signed integer values which will take the spectrum data The array starts at channel O and has a maximum of 8192 channels The return value of ReadData is a 32 bit signed integer It must be O if the file was read successfully Any other return value indicates an error condition The calling convention of ReadData must be stdcall in Borland Delphi or WINAPI in Microsoft C A small code example in Pascal can be found in UserDLL sample dpr A more detailed example is given in UserDLL sample1 dpr The code examples are in Pascal Borland Delphi 4 61 3 Using SIMNRA 3 16 Adding new cross section data To add new cross section data you have to perform the following steps 1 Create a cross section data file in the R33 file format The easiest way to do this is by using the R33Manager Alternatively you can use any text editor The file format is described below 2 Copy this file into the directory where all other cross section data files are subdirectory CRSEC of your SIMNRA installation 3 Recreate the reaction list by clicking Options Create Reaction List Note If your file is ignored SIMNRA was not able to read or understand the file Carefully read the section about the R33 file format and try again The nuclear data section of the International Atomic Energy Agency IAEA has created the Ion Beam Analysis Nuclear Data Library IBANDL at http www nd
228. y recipe for the best choice of a fixed stepwidth Usually the best compromise between speed and accuracy is automatic stepwidth control Cutoff Energy All particles are calculated until their energy has decreased below the cut off energy You may speed up the calculation if you increase the cut off energy The lowest possible value for the cut off energy is 1 keV the default value is 10 keV Pile up tab e Pile up model Selects the model for pile up calculations see subsection 4 11 2 The Fast model is less accurate but is calculated fast The Accurate model is closer to physical reality but the calculation takes much longer The computing time is about oc N with N the number of channels in the spectrum for the Accurate model but only N for the Fast model For 1000 channels the Fast model is more than 1000 times faster The Fast model can be applied if a pile up rejector is used and the pulse rise time is larger than about 1 us The Accurate model should be used if the measurement was done without a pile up rejector or if fast pulses are used i e if the pulse rise time is smaller than 1 us See subsection 4 11 2 especially Figure 4 31 for more details Default is the Fast model Note Several parameters in the Setup Experiment Live time and pile up form are only available if the Pile up model is set to Accurate see section 3 6 2 Roughness tab Number of thickness steps Used for the calculation of layer roughness
229. y resolution of TOF detectors 4 7 2 Electrostatic detector The energy resolution of electrostatic detectors is given by the constant ratio EE 53 ES 4 53 with AE the detector energy resolution full width at half maximum FWHM and E the particle energy This relation is used for all particle species 92 4 Physics 4 8 Straggling 4 8 1 Overview When a beam of charged particles penetrates matter the slowing down is accompanied by a spread in the beam energy This phenomenon is called straggling It is due to statistical fluctuations of the energy transfer in the collision processes Energy loss straggling has different contributions 1 Electronic energy loss straggling due to statistical fluctuations in the transfer of energy to electrons 2 Nuclear energy loss straggling due to statistical fluctuations in the nuclear energy loss 3 Geometrical straggling due to finite detector solid angle and finite beam spot size resulting in a distribution of scattering angles and different pathlengths for outgoing particles 4 Straggling due to multiple small angle scattering resulting in angular and energy spread on the ingoing and outgoing paths 5 Straggling due to surface and interlayer roughness and thickness inhomogeneities of absorber foils An additional contribution to the energy broadening visible in experimental spectra is the energy resolution of the detector The different straggling contributions excluding

SIMNRA User's Guide - Max-Planck

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