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CREPT-MCNP 1.1

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1. 1 1 0 2008 7 7 CREPT MCNP 1 1 Calibration Code for the Representative Point Method with MCNP p n Ge 20 keV 2 MeV CRBPT MCNP1 1 Windows PC GUI CREPT MCNP
2. 319 119 2 4 JAEA Data Code 2008 017 Contents 1 Introduction 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 2 CREPT MCNP Code User Manual oe 2 1 System Requirements oe PCIE SL 2 3 Directory Configuration ee 2 4 Basic Operation ee 2 5 Operation Menus oe 2 5 1 File Menu no 2 52 Data Menu mmm enne enne nennen nennen nennen nennen nennen nnn 2 5 3 Calculation Menu ee 2 5 4 Calculation Results Menu ooo 3 Efficiency Calibration of Radioactivity Measuring Instrument with the Representative Point Method 000000000000000000000000000000000000000000000000000000000000000000000000000009 3 1 Present Status of Efficiency Calibration i CE ee i 0 0 I a E 3 2 Efficiency Calibration with the Representative Point Method m8 3 3 Utilisation of CREPT MCNP Code 3 3 1 Calculation time needed for efficiency calibration M 3 32 Uncertainty estimation 34 Application of the Method P0 4 Summary and Perspective for the Put Acknowledgements
3. sr d mC SI 4 SI e SL SI gt m kg s Jj y PB m kg s x kg s m m s s f XR HE mem s s kg s ske Qe MRM Ta p he did ES eju sz s EE B K c ZA p SP pos m K m kg s K B dE eode Sep AAs EP amp RF o A sp esc gw SUPE x 7 REG XR P d A x Bg sek 5 i m ekg stea le x5 m kg s A X m KR JJ HV om JV f CE jV kg s mol I JV ze J mol K m kg K mol
4. 1 Default A default style of a tray 1s selected by clicking the button on the right side of the blank line Users can browse and select the intended file Parameter values of the default tray are then modified to specify the intended tray The default style itself cannot be modified on the GUI window but it can be modified or newly added in a text file The description format of the file is in Appendix A 8 Originally the CREPT MCNP code has a plate shaped tray as a default style tray Geometry of the tray is shown schematically in Fig 2 5 along with its parameters and default parameter values in Table 2 5 JAEA Data Code 2008 017 2 nn 1 3 Fig 2 5 Half sectional view of a default tray Table 2 5 Parameters data type and parameter values of the default tray File name disk csv Parameter paatpe Defaut 3 Material of tray Character JAEA Data Code 2008 017 2 5 2 5 Data Support jig Menu Support jig is another part around a detector It might be used as an attachment to join the end cap ofa detector and a cover Parameters to specify the geometric configuration and material of the support jig can be assigned in the following window Eiig window for data oriqinationT eflondig csY 1 Default A default style of a support jig is selected by clicking the button on the right side of the blank line Users can browse and select the necess
5. References MERI Appendices Format Description of Input and Output data 888 A 1 Output File for the Efficiency Curves Group A seem A 2 Output File for the Efficiency Curves Group B seem A 3 Output File for Position of the Representative Point and Parameter t 7770000668 A 4 Output File for the Efficiency Curves Used for Self Absorption Correction neo A 5 Output File for the Final Efficiency Clin a BMB A 6 Input File for Measured Efficiency Curve at the Representative Point 77568 A 7 Input File for Angular Dependence of Efficiencies seem A 8 Description of Basic Element eesesossssesoscseesoocceesososeesoocceesoscseesoocceesososeecoocceesescseceoooceeceocceee lil JAEA Data Code 2008 017 ME 315 OANA 1 2 CREPT MCNP 2 AE pt 2 4a S A re 2 5 DEP US 2 6 DH e o 8 2 5 1 Q 2055 qoc A c au pssdemictimip De tgu Cm mm 9 E ae 35 2 5 4 45 3 wo 3 21 PSST De INN 53 TE o F cs Oe ee A 54 EGR 56 WS CC E EEE 56 252 cu uds EN nesansuuntqettussiix tete dread NEUE ES 57 A n E E 57 4 oo 58 Ene 58 seeeeeeeceeceeceeeceeeceecceeceecoeecoeccoeccceceeeoceccecocesoceccecoeecoecocecececcceoeeeeceecesoceceecocec
6. 6000 Re S000 0 31961 782 1 Comment Space provided just for user made comments 2 Number of element s Specify the number of element s or nuclide s which constitute a material This will automatically change the number of rows in the data grid at the bottom of the window 3 Density g cm Assign a density of the material in g cm 4 Specification of composition Select an input form to specify the material composition Either Atomic fraction or Weight fraction can be selected 5 Data grid Element nuclide Specify elements or nuclides which constitute a material in ZA format With the ZA format a nuclide with the atomic number of Z and the mass number of 4 is expressed as Zx1000 A A is zero for a natural element Example H hydrogen 1000 Co cobalt 27000 H tritium 1003 and Co cobalt 60 27060 JAEA Data Code 2008 017 6 Data grid Fraction In accordance with the specification of composition assign the appropriate fractions for the constituents specified in the left columns The sum of the fractions does not need to be unity as the MCNP code will renormalize the fractions if they do not sum to one 2 5 2 2 Data Detector Menu Parameters that specify the geometric configurations and materials of a detector are assigned in the following window detector window for data originationnGe3 csv NS a en bm ES EN TES Em
7. Shielding box x e St Photo 3 2 Example of an apparatus for setting a standard point source at the desired position Step 3 The absorption effects are corrected by multiplying the measured efficiency curve at the representative point P FgpZnp by the correction factors F E calculated with the MCNP code as V AE F ae 4 where Vingiix E 1s the efficiency for a volume sample with sample material and sample container and V E is that with air And consequently the intended peak efficiency curves can be obtained 3 3 Utilisation of CREPT MCNP Code 3 3 1 Calculation time needed for efficiency calibration For attaining a certain statistical level calculation time of each MCNP run ranges from several tens of seconds to 30 minutes depending on the photon energy complexity of the calculation geometry the source position and materials used Accordingly the total calculation time required for completing the efficiency curves group is approximately one week in a condition that the statistical uncertainty in each result is 2 and that twelve energy points and 150 positional points thus 1800 MCNP calculations are assumed Although this may seem time consuming users do not have to repeat this process once the efficiency curves group has been obtained with respect to each detector That is the typical time required for the efficiency calibration is within an hour much of which is spent for the Monte Carlo calc
8. X y kg s A 7 WX ES mes m m kg s m kg ER e FE p dE n m 2 e kg kg 3 cdd SI N A NY gt H 7 p X 4 7 3 A ILS BRL 8 N SE MI Yy 266 ica RED SI min 60s 1h 60 min 3600 s H 1 d 24 h 86400 s 1 2 180 rad 1 1 60 2 10800 rad 1 1 60 2 648000 rad 11 1 dm 10 m 1t 10 kg 1Np 1 1B 1 2 1n10 Np 7 ST SI 1eV 1 60217733 49 x10 J lu 1 6605402 10 x 10 kg X x H 1ua 1 49597870691 30 x 10 m 8 SI 1 1852m 1 1 1852 3600 m s 1 a 1 dam 10 m 1 ha 1 hm 10 m 1 bar 0 1MPa 100kPa 1000hPa 10 Pa 1 A 0 Inm 10 m 1 b 100fm 10 m a9 CGS
9. SI ee Jv ereg 10 J dyn 10 N ns y P 1 dyn s cm 0 IPa s A k 4 3 St lem s 10 m G 810 T TJA F E Oe 1000 4 x A m ue WA Al Bev Mx 210 Wb A F pa sb 1cd cm 10 cd m ZR ph 10 1x Gal lem s 10 m s 210 SI m dw 1 Ci 3 7X 10 Bg pre ge 4 us 1 R 2 58X10 C kg 1 rad 1cGy 10 Gy 1 rem 1 cSv 10 Sv 1X unit 1 002 X 10 nm 1 l ma10 T vu de Sees 1 Jy 10 W g 7 Hz z Jb 1 fermi 1 fm 10 m 1 metric carat 200 mg 2X10 kg 1 Torr 101 325 760 Pa E 1 atm 101 325 Pa u pe Z 1 p lym 10 m 7 1998
10. Point of origin Z cm Point of end Z cm Precision of a point source setting cm m JE Ie ia dr ir dz iz ang ia DULPIATLH 32 142 10 3410000 2 10000 20 le o E U Lattice number of a representative point R Lattice number of a representative point 2 Lattice number of a representative point 4 R coordinate of a representative point cm Z coordinate of a representative point cm Angle of a representative point degree Parameter 7 0 01 m ENERGY AVR DATA AVR ERROR POINT DATA P ERROR SPH ERROR 6 0000E 02 lLl l724E 053 9 2449E 07 1 2347E 05 7 5295E 02 0 000ET00 8 9D0D0E U02 D 2090E 02 4 7295E 02 0 0597E 059 4 1869E 02 0 0008 00 1 2200E 01 1 525I1E 02 3 0201E 02 1 49035E 02 2 0192E 02 0 000ET00 l 6000E 0Il 2 74598E 02 2 2221E 02 2 7007E 02 1 9166E 02 0 000ET00 2 1900E 01 4 8834E 02 1 6368E 02 4 8758E 02 1 4052E 02 0 000ET00 249200E 01 5 0277E 02 11 2595LE 02 0291E5 02 1 2507E 02 0 000ET00 Ss 14UU 01 2 66985 02 1 2720E 02 6 6528E 02 1 1909b 02 0 000ETUD 6 0200E UIl T 1260E 02 1 32145b 02 T7 1209E 02 1 1427E5E U2 0 000ET00 904 9900E U0l 7 5041E 02 1 2925E 02 7 5002E 02 1 1095E 02 0 000ET 00 l L7290BET 0 1 02195b 02 1 2540E U2 T9075E 072 L 0905E 027 0 000ETD00 L 3330H 00 7 9457E 02 1 2447Eb 02 7 92239E 02 1 08625 02 0 0005T00 1 903G00ETUD O19595 02 1 2241E 02 98194205202 06 802 000ET00 Energy MeV Spline interpolated efficiency of a volum
11. SI SI ST P mo ae Y v 3 mem 1 m m 1 P s m kg s E d 3 J m kg s m kg s T 3 RV m kg s E mM E s A m kg s A 7 m kg s A m kg s A et me ekg s A hi m e kge s A hi TE kge s A m kg s A7 de yp ce m cA du BE K zr m m cd cd Ha ES m m cd m cd 7 L 2 2 i ik mes aJ 2 4 b rad sr 1 n le c
12. bcm Bi Em Em TR EE ER TR lA EA TE ica 1 Default First a default style of a detector should be selected By clicking the button on the right side of the blank line users can browse and select the necessary file Parameter values of the default detector are then modified to specify the intended detector The default style itself cannot be modified in the GUI window but can be modified or newly added in a text file The format of the text file is described in Appendix A 8 Originally the CREPT MCNP code has a p type HPGe and an n type HPGe as the default detectors Geometries of these detectors are shown schematically in Figs 2 2 for p type HPGe and 2 3 for n type HPGe along with their parameters and default parameter values in Tables 2 2 for p type HPGe and 2 3 for n type HPGe JAEA Data Code 2008 017 Se SE 0 05 EH l 2 i 1 10 11 E 9 7 4 1 JL 5 Fig 2 2 Half sectional view of a default p type HPGe units in cm Table 2 2 Parameters data type and default parameter values for a p type HPGe File name ge TypeP csv Parameter Datatype Default Total length of detector cm Floating point 2 Distance from upper surface of detector case to upper surface of Floating point 0 43 Ge crystal cm Length of Ge crystal cm Floating point Thickness of dead layer cm Floating point 0 09 Thickness
13. detector and a calculation area are both essential to the calculations their file names must be assigned without exception Attention should be paid when users are creating the geometric models for the self absorption correction factor calculations In calculations of the self absorption correction factor users will need to create two types of geometric models one is with sample material and with sample container and the other 1s without either of them In the case users use a tray for a measurement of a volume sample the tray should be selected in a calculation with sample material and a sample container and should be checked off for a calculation without either of them unless the tray is included in the calculation geometry for obtaining efficiency curves group A In the calculations of the efficiency curves group A normally the tray should be considered to be part of a sample container rather than as part of a detector because it intervenes with the setting of the Marinelli shaped sample JAEA Data Code 2008 017 Once a geometric model has been saved in a file it can be re opened and re edited in the window Note however that any change given on parts through the Data Cover Menu Data Tray Menu Data Support jig Menu Data Measured sample Menu and Data Calculation area Menu These data are stored in the Work parts folder is not reflected automatically just by opening a geometric model file If any of these p
14. detectors MHR Sors daa of deuk coves TERE T Stores data of default trays jig APAE A REE Stores data of default support jigs 0 Stores data of default measured samples eaten ane Stores data of default calculation areas De RS RE RRR RO A CECE RE eR CR Stores data created by the system and calculation results LE Stores data of angulat dependency not used in this version of the code Stores data used for post processing with the Microsoft Excel Stores data of efficiency curves group A SR peee Stores data of efficiency curves group B TERI II Stores data of representative point RP and parameter P2 M Stores data of material compositions and densities M Stores measured efficiency data at RP with a standard point source Stores geometrical model data for MCNP calculations 7 1 2 Stores data of parts user established data detector Jj Stores data of detectors Cover Stores data of covers tray 990900900900990900900900900990999 Stores data of trays jig pee Stores data of support jigs EE Stores data of measured samples 0 RSS daa of acuanana ina M E Stores data of calculated self absorpti
15. hl Height cm DBL 1 f cm 1 0 ri Radius cm DBL 1 re cm 42 0 mnO Material Al ME B MAT mnl Material B MEE B MAT These are user variables A variable consists of Variable Name Comment Type Default It must be arranged on one line with comma delimiters 1 Variable name The variable names are expressed in alphanumeric characters Lower case alphabets must be used 2 Comment A meaning of the variable should be given The comment appears on the GUI screen and it can be expressed in either English or Japanese A pipe character must be placed in between the comments in two different languages Japanese comments must be located after English comments In the case that there is only an English comment or only a Japanese comment the pipe must be excluded 3 Type Data type for the input data must be selected from the following list blank none specified DBL floating point number JAEA Data Code 2008 017 DBL 0 positive includes zero floating point number DBL 1 positive excludes zero floating point number DBL 0 negative includes zero floating point number DBL 1 negative excludes zero floating point number MAT Material data 4 Default In the case the type is MAT the default should be left blank Otherwise assign an intended default value UN LM pm HR ARN eS MO 3Y E 3 SI
16. 1 File name final efficiency curve A file containing the final efficiency curve data should be selected The file is created in the Calculation Final efficiency curve Menu By clicking the button on the right side of the blank line users can browse and select the necessary file 2 Button Call EXCEL By clicking this button the efficiency data and graph can be exported to a Microsoft Excel spreadsheet JAEA Data Code 2008 017 3 Efficiency Calibration of Radioactivity Measuring Instrument with the Representative Point Method 3 Present Status of Efficiency Calibration In order to estimate the radioactivity in a volume sample nondestructively the gamma ray spectrometry method with a germanium semi conductor detector is generally used In the method the peak efficiency curve must be evaluated in advance of the measurement Procedures for obtaining the peak efficiency curve are called efficiency calibration There are many studies related to the efficiency calibration for radioactivity quantification for a volume sample Most of them are classified into three types such as comparative measurement with a standard volume source analytical calculation and the Monte Carlo calculation In the first method the comparative measurement the peak efficiency is estimated from the peak counting rate measured by a germanium detector on which a standard volume source is set And for this the standard volume sources with known radi
17. 1 00 Energu M ev 1 File name efficiency curves group A A file containing the data of efficiency curves group A should be selected The file is created in the Calculation Efficiency curves group A Menu By clicking the button on the right side of the blank line users can browse and select the necessary file 2 File name angular dependence of efficiency This option cannot be used at the moment Leave the space blank 3 R direction Z direction The lattice number in the R or Z direction should be selected The corresponding coordinate value cm for the lattice number will then be displayed to the right of the lattice number JAEA Data Code 2008 017 4 Button Call EXCEL By clicking this button the efficiency data and graph can be exported to a Microsoft Excel spreadsheet as follows El Microsoft Excel effcurve xls F me RTV BAD BAO T 2220 0 J200 0gHadlaa T xaa y 0 c amp xii je B 221 m A B Efficiency curve Energy MeV at R 10 000 2 0 022 0 060 0 088 0 122 0 166 0279 0 392 0514 0 662 0 898 1178 1 333 Effici t iciency curve a 1 836 R 10 000 2 2 000 Energy Me V fig Efficiency curve Efficiency 23 M 4 gt MNGraph1 Sheeti Sheet2 Sheet3 SEHE 2 5 4 2 Calculation Results Efficiency curves group B Menu Users can plot the calculated efficiency curve
18. Tokai Japan 1995 J Saegusa T Oishi K Kawasaki M Yoshizawa M Yoshida T Sawahata and T Honda Determination of gamma ray efficiency curves for volume samples by the combination of Monte Carlo simulations and point source calibration J Nucl Sci Technol 37 pp 1075 1081 2000 J Saegusa K Kawasaki A Mihara M Ito M Yoshida Determination of detection efficiency curves of HPGe detectors on radioactivity measurement of volume samples Applied Radiat and Isotopes 61 pp 1383 1390 2004 J Saegusa CREPT MCNP code for efficiency calibration of HPGe detectors with the representative point method Applied Radiat and Isotopes 66 pp 774 779 2008 X 5 Monte Carlo team RSICC MCNP Monte Carlo N Particle Transport Code version 5 Oak Ridge National Laboratory LANL Manual LA UR 03 1987 Los Alamos USA 2005 JAEA Data Code 2008 017 Appendices Format Description of Input and Output data Note In the following appendices texts in red characters font type the Times New Roman are merely comments for this manual A Output File for the Efficiency Curves Group A line xxi E x j j x This type of file is stored in the work effa folder Any line beginning with a 66499 means a comment Model ge Energy 12grp Mesh point NPS 10000 Precision 0 05 MaxTime 0 Lines beginning with cannot be removed They are used in the
19. angular dependence correction factor Q E R Z 0 As a result an angular dependent efficiency P E R Z 0 is obtained The format of this file is as follows 12 3 2 4 12 Number of measured energy points Number of planes Z Number of planes R Number of measured angular points Recommended number is at least 8 Number of angular partitions 00221 0 05995 0 088 QU 1221 1505 Q 1659 10 3917 0 6017 Measured energy points MeV UNS zl 4 1 Position of planes Z cm OO 2 6 Position of planes R em 0 0 900 180 0 2 1 Measured angular points degree 1 0000 220000 1 0000 1 0000 l 0000 1 2430 1 9150 1 1212 1 0000 1 0000 1 0000 1 0000 140000 1203595 0 9594 0 9615 1 0000 1 0000 1 0000 1 0000 1 0000 1 0495 1 0030 0 9667 1 0000 1 0000 1 0000 1 0000 1 0000 1 2212 12920 1 1062 10000 1 0000 1 0000 1 0000 140000 1 0499 0 9950 10 9554 1 0000 1 0000 1 0000 10000 t0000 1 0459 L 0127 0 9009 1 0000 1 0000 1 0000 1 0000 1 0000 1 1947 1 2478 1 0885 1 0000 1 0000 1 0000 1 0000 1 0000 1 0719 10 999045 1 9963 1 0000 1 0000 1 0000 1 0000 10000 L03995 1 0500 0 970695 efficiency data 171 Number of measured angular points j 1 Number of planes R k 1 Number of planes Z I 1 Number of measured energy points JAEA Data Code 2008 017 A 8 Description of Basic Element This type of file should be stored in a sub folder located in the system parts folder Any line beginning with a means a comment line
20. for the representative point method is to be examined for a Japanese patent by the Japan Patent Office and has been made with an Application Kokai Publication Number of 2002 98768 This is a blank page JAEA Data Code 2008 017 1 Introduction One of the most important tasks with the radiation control work is precisely and promptly measuring radioactivity in environmental samples And in addition with the rapid widespread use of accelerators these days the urgent need to be able to estimate the induced radioactivity in activated samples of various shapes and materials has arisen Radioactivity measurements for these purposes are generally based on gamma ray spectrometry using HPGe detectors In order to quantify the radioactivity an efficiency calibration viz determination of the peak efficiency curves versus energy must be achieved for various combinations of sample detector geometries The shape and magnitude of the peak efficiency curve depends on the detector sample shape and sample material Generally efficiency calibrations are performed by manufacturing a standard volume source spiked with a known amount of radioactivity and then measuring it with the detector Manufacturing standard volume sources however requires skilful and complicated techniques 8295 and the procedure must be repeated periodically as they contain rather short lived nuclides Furthermore differing standard volume sources must be prepared depending on the
21. in a graph on the screen Both the horizontal axis photon energy and vertical axis peak efficiency are in logarithmic scales Users cannot change ranges of these scales However if needed users can export the data to a Microsoft Excel spreadsheet 1 Microsoft Excel version 2002 or later is necessary JAEA Data Code 2008 017 HE Graph of efficiency curve Me Call EXCEL Close Select data for display File name efficiency curves group B Ri direction f 43 12 300 cm Z direction 115 0500 em Efficiency Efficiency curve at A 12 900 0 500 1 00 Energu M ev 1 File name efficiency curves group B A file containing the data of efficiency curves group B should be selected The file is created in the Calculation Calculation of efficiency curve for volume sample without self absorption representative point Menu By clicking the button on the right side of the blank line users can browse and select the necessary file 2 File name angular dependence of efficiency This option cannot be used at the moment Leave the space blank 3 R direction Z direction The lattice number in the R or Z direction should be selected The corresponding coordinate value cm for the lattice number will then be displayed to the right of the lattice number 4 Button Call EXCEL By clicking this button the efficiency data and graph can be exported to a Microsoft Excel spreads
22. in the interpolated peak efficiencies at points near the detector which are obtained by the Spline interpolation with the efficiency curves group A data For example because the peak efficiency in the vicinity of a detector tends to change drastically in the range between 0 and 2 cm from the top surface of a detector or a cover it is effective to set additional coordinate points at 0 5 cm and 1 0 cm in the Z direction Introducing this setting will reduce the difference between the interpolated and actual efficiencies The other purpose is to obtain point source efficiency data efficiency curves group B data at a region which intervenes the outermost part an end cap of a detector or cover and the innermost lattice points the shaded region in Fig 2 11 Setting the additional coordinate points just over the outermost part line B in the figure enables the Spline interpolation in a region between the added points and the original lattice points D D D Calculation area AD D D K v Original lattice Detector points me D i n NU Fig 2 11 Lattice points around a detector half sectional view 4 Configuration of a source At the time of writing only a point source without a source holder had been verified as an option Users therefore should select Sheer point at this stage In most cases this will bring about reasonable results JAEA Data Code 2008
23. individual sample s shape and material which can result in an undesirable increase in radioactive waste as one has to get rid of them Although peak efficiency curves can be determined using only computational approaches the reliability of the results cannot be ensured mainly due to difficulties in modelling the detector on particular with parameters such as the dead layer or the ineffective region of the germanium crystal Jo06 He03 To overcome this problem the representative point method a novel method which enables efficiency calibrations using a standard point source has been previously proposed S200 Sa04 and a calculation code for implementing the method newly developed Sa08 The code is named CREPT MCNP Calibration Code for the Representative Point Method with MCNP The code finds the position of the representative point the position where a point source efficiency curve better approximates that one for the volume source Self absorption correction factors are also computed to make correction on the efficiencies measured at the representative point with a standard point source It involves the general purpose Monte Carlo code MCNP Br00 XM05 for simulating radiation transport in and around the sample and detector The developed CREPT MCNP code has MCNP control functions e g creation of input files and simulation with MCNP as a GUI Graphical User Interface based application Even novice MCNP users can carry out efficienc
24. of analytical calculations and measurements of a standard source The standard source may be point like planate or with a finite volume In the calculation rigorous modeling of a detector or volume source accompanies complicated mathematical formulae in a classificatory scheme which hampers smooth efficiency calibration The third method the Monte Carlo makes it possible to describe the geometric model freely by JAEA Data Code 2008 017 employing a three dimensional treatment The method has had a weakness that it usually requires a great investment of time to finish the calculations However recent advances in computer technology made it easier to get high performance computers less costly and because of this the Monte Carlo method is becoming increasingly more practical Both the analytical calculation and the Monte Carlo methods require detailed geometrical information inside a detector which is often difficult to be determined In particular the dead layer of the crystal and the distribution of charge collection efficiency inside the detector cannot be known accurately To supplement these data preliminary experiments or the sensitivity analysis are usually performed for the determination of geometric parameters Na83 but this procedure is very complex and our experiences suggest that there still may exist considerable difference as large as some ten percent between the calculated peak efficiency and the measured one even if the pa
25. point JAEA Data Code 2008 017 2 5 4 6 Calculation Results Comparison of efficiency curves of a volume sample by means of point integration and by MCNP Menu In this menu users can compare two efficiency curves Both are efficiency curves of an air equivalent volume sample but processes used to estimate each curve differ One curve red curve in the figure is obtained by means of the point integration with the data of efficiency curves group C and the other blue curve is calculated by simulating volume source bulk sample in MCNP These two efficiency curves may well be identical if the accuracy of the Spline interpolation was sufficient Otherwise users should check over the geometric models used for the calculations Both the horizontal axis photon energy and vertical axis peak efficiency are in logarithmic scales Users cannot change ranges of these scales However if needed users can export the data to a Microsoft Excel spreadsheet HE Graph of efficiency curve B x Call EXCEL Close Select data for display File name representative point GE Sai File name efficiency curve for volume sample without material container BE3 7 Hair 4cm n Efficiency Efficiency curve by point integration of efficiency curves group Efficiency curve of by MCNP volume source 1 00 Energu M ev 1 File name representative point A file containing the calculated results of the representative point s
26. sample Relative uncertainty efficiency at a representative point Relative uncertainty Maximum difference of efficiencies between that of at a representative point and at each position within R CHK SPH absolute value t map data Z R 0 00000 D LODOO 0 20000 JAEA Data Code 2008 017 12 00000 1 0000H 28 1 0Q000E 28 1 0000E 28 LL90000 1 00005128 1 0000EtT29 L 0000ET29 11 50000 1 0000E1258 1 00005729 1 00000E 28 11 70000 L1 0000ET29 L1 0000ET298 L 0000ETZ29 snip I1 00000 L DODORT29 lL 0000ET25 10000ETZ9 LI50000 1 0000ET298 1 0000ETZ29 1 000058T298 11 40000 1 0000ET296 1 0000ET25 L1 0000Ef29 11 30000 1 0000ET298 1 0000ET28 L1 0000ET29 Map of parameter t snip 2 R 1 00000 1 10000 1 20000 14 00000 1 0000ET298 J1 0000K426 1L1 0000ET29 2 In the case a file related to the angular dependence was assigned This option is not used in this version of the code In such case distribution of parameter on the R Z plane and the R A angle plane is read out on the file 3D used as an identifier to specify that there is the angular dependence in the efficiencies x IMAX JMAX KMAX NE R START R END Z4 START Z4 END R CHR obn 161 281 120 12 0 00000 5 00000 0 20000 5 20000 0 000 Number of positional points R Number of positional points Z Number of angular points Number of energy points Region occupied by a sample Point of origin R cm Point of end R cm
27. the dead layer or the charge collection efficiency in the crystal which is one of the advantages of the representative point method 3 4 Application of the Method By using the representative point method non destructive quantification of the radioactivity of various volume samples can be readily performed The efficiency calibration with the representative point method can be applied in the area of environmental monitoring around nuclear facilities surveillance in emergency situations and measurement of the induced radioactivity in activated samples The method has also been utilised as a radioactive gas monitor with a built in germanium detector O101 The efficiency calibration for these monitors requires standard gas sources Because it is generally rather difficult to prepare a variety of unsealed radioactive materials only a limited number of energy points are available for the calibration For such case the representative point method can be applied for complementing the energy points and extending energy range JAEA Data Code 2008 017 4 Summary and Perspective for the Future A GUI based application has been developed to provide the peak efficiency curves of radioactive volume samples set around an HPGe detector The code CREPT MCNP facilitates implementation of the efficiency calibration based on the representative point method For a variety of samples the code allows users to determine the position of the representative po
28. uncertainty originates from various factors related to the calculation e g reliability in the geometric model cross section data and so on Users can assign non statistical uncertainties as their best estimates in the data grid The uncertainties should be set in their relative values If users wish to put uniform values in the data grid irrespective of the source energy it can be done by assigning the value in the Set all textbox 5 Number of particles The number of source particles per batch refer to the following 6 and 7 with regard to the batch 1s set in the textbox The default value is 100000 6 Statistical accuracy termination condition Assign the statistical accuracy at which to terminate a calculation Each calculation consists of several sub calculations which are segmented into source particle batches That is the sub calculations are automatically repeated until the statistical accuracy 1s equal or less than the assigned value The default value is 0 01 JAEA Data Code 2008 017 7 Maximum calculation time min Assign the maximum calculation time to terminate a calculation This option is useful for calculations which users expect a long calculation time to reduce the statistical accuracy such as those with predominant interactions between photons and high shielding material A calculation consists of several sub calculations which are segmented into source particles batches The sub calculations are au
29. 0 0 00000 0 27900 1 206002 0 04550 0 00000 0 39200 9 456 0023 0 04570 0 00000 0 51400 8 32e 003 0 04880 0 00000 0 66200 7 00e 003 0 04860 0 00000 0 89800 6 00e 003 0 04860 0 00000 ABU0U Saloe 008 0 049200 0 00000 1 332900 4 016002 0 04790 0 00000 1 83600 4 54e 003 0 04930 0 00000 JAEA Data Code 2008 017 A 5 Output File for the Final Efficiency Curve 66 This type of file is stored in the Work selfeff folder Any line beginning with a means a comment line Energy Count l2 Number of energy points Energy MeV Measured efficiency final efficiency variance 5 total variance variances are expressed in their absolute values Energy Measure Det baril bar2 bar3 bar4 bar5 bar total k 2 6 000e 02 0 000e 01 4 6187e 02 1 00e 02 4 4085e 03 9 3620e 03 0 00e 000 4 3987e 04 4 3719e 02 8 800e 02 0 000e 01 6 1464e 02 0 00e 02 1 3324e 02 2 3561e 02 0 00ef000 6 6847e 04 5 6525e 02 1 220e 01 0 000e 01 7 1851e 02 0 00e 02 1 9638e 02 2 6414e 02 0 00e 000 7 3652e 04 6 8736e 02 1 660e 01 0 000e 01 7 2738e 02 0 00e 02 1 8735e 02 2 4929e 02 0 00e 000 7 1395e 04 7 0340e 02 2 790e 01 0 000e 01 7 3812e 02 0 00e 02 1 2967e 02 1 8405e 02 0 00e 000 6 1114e 04 6 8128e 02 3 9208 01 0 000e 01 8 2573e 02 0 00e6e 02 1 9400e 02 1 3360e6e 02 0 00e 000 5 2648e 04 7 8058e 02 5 140e 01 0 000e 01 8 4892e 02 0 00e 02 8 8484e 03 1 8190e 02 0 00e 000 4 7419e 04 7 8204e 02 6 620e 01 0 000e 01 8 5097e 02 0 00e 02 7 4614e 03 8 8143e 03 0
30. 00 0 0000E 00 12 00000 0 40000 0 00000E 00 0 0000E 00 0 0000E 00 0 0000E 00 Z coordinate cm R coordinate cm peak efficiency relative uncertainty NE snip 12 00000 4 00000 2 4200E 03 6 4200E 02 5 6800E 03 4 1800E 02 12 00000 4 10000 2 4401E 03 6 6899E 02 5 7532E 03 4 3158E 02 12 00000 4 20000 2 4445E 03 6 9451E 02 5 7928E 03 4 4375E 02 JAEA Data Code 2008 017 A 3 Output File for Position of the Representative Point and Parameter 7 66499 This type of file is stored in the work effc folder Any line beginning with a means a comment line The format of this file may differ depending on whether users has assigned a file for the angular dependence characteristics of efficiencies in the Calculation Calculation of efficiency curve for volume sample without self absorption representative point Menu 1 In the case a file related to the angular dependence was not assigned The distribution of parameter on the R Z plane is read out on the file EffA GE3 out RDiv 20 ZDiv 20 Angle RDivS 10 ZDivS 10 Source GE3 70H csv Model GE3 70Hair 4cm airtray csv Lines beginning with a cannot be removed They are used in the system IMAX JMAX NE R START R END Z START Z END R CHK SPH rer 321 13 0 00000 SxD00D0DD EUUODD 500000 0 00000 Number of positional points R Number of positional points Z Number of energy points Region occupied by a sample Po
31. 00e 000 4 3012e 04 8 3060e 02 8 980e 01 0 000e 01 8 5346e 02 0 00e 02 6 2797e 03 7 1783e 03 0 00e 000 3 9015e 04 8 2492e 02 1 173e 00 0 000e 01 8 1369e 02 0 00e 02 4 9718e 03 5 4960e 03 0 00e 000 3 5745e 04 7 8174e 02 1 333e 00 0 000e 01 8 2829e 02 0 00e 02 4 7216e 03 5 2586e 03 0 00e 000 3 4537e 04 8 0920e 02 1 836e 00 0 000e 01 8 4825e 02 0 00e 02 3 8937e 03 4 2047e 03 0 00e 000 3 1109e 04 8 1741e 02 variance 1 variance 2 variance 3 variance 4 JAEA Data Code 2008 017 A 6 Input File for Measured Efficiency Curve at the Representative Point 66 This type of file should be stored in the work meas folder Any line beginning with a means a comment line EnergyCount 12 Number of energy points Energy MeV Efficiency Uncertainty 0 06000 0 10000 0 05540 0 06800 0 10000 0 03210 0 12200 0 10000 0 02040 0 16600 0 10000 0 01610 0 27900 0 10000 0 01280 0 39200 0 10000 0 01200 0 51400 0 10000 0 01150 0 66700 0 10000 0 01130 0 89800 0 10006 0 01110 1 17300 0 10000 0 01090 1 323300 0 10000 0 01090 1 83600 0 10000 0 01070 Energy MeV Measured efficiency Relative uncertainty 0 01 Values in each line should be delimited with space characters JAEA Data Code 2008 017 A 7 Input File for Angular Dependence of Efficiencies This option is not used in this version of the code This type of file should be stored in the Work angle folder In the code an efficiency data P E R Z is multiplied by an
32. 017 2 5 3 Calculation Menu 2 5 3 1 Calculation Efficiency curves group A Menu With this menu a series of Monte Carlo calculations is carried out in order to obtain the Efficiency curves group A E Calculation of efficiency curves group A 1 File name Calculation geometry A file defining a geometric model which includes a detector a calculation area and other optional parts possibly a cover and or support jig but usually excludes a tray because it hampers the setting of a Marinelli shaped sample should be selected by clicking the button on the right side of the blank line The file can be created in the Data Geometry Menu and users can browse and select the created file 2 File name Energy points A file defining a data group of the source energy points should be selected by clicking the button on the right side of the blank line The file can be created in the Data Source energy point Menu and users can browse and select the created file JAEA Data Code 2008 017 3 File name Calculation area A file defining the lattice point should be selected by clicking the button on the right side of the blank line The file can be created in the Data Alignment of point source Menu and users can browse and select the created file 4 Checkbox Recalculate Users can recalculate a series of calculations by checking the checkbox This option takes effect by assigning an un
33. An element is defined in an input file by considering the four arithmetic operations for the variables of each element dp amp KK KK KK KK KKK KK KK KK KKK kk KK KK ck k Ck kk kk kk ck Ck Ck CkCk kk KK KK KK KKK KKK i Parts File dp KK KK KK KK KKK kk KK KK KKK kk KK kk KK Ck kk kk kk ck Ck KKK kk kk KK KK KKK KKK BODY count2 6 lt Number of BODYs to define BODYSymbol Parameter count2 Parameter 1 Pzd pos 2 pz l 95pos 0 05 3 Bel COS VD 4 pz 1 pos hl 5 cb tee 6 Gerdy nrl Definition of BODYs The BODY has basically the same meaning with the surface used in MCNP Data of BODY must be arranged in sequence on one line per single BODY in the order of the body code number of parameters used parameters parameters repeated as many as the number of parameters These parameters are delimited by commas Positions in the Z direction must be set on the basis of pos variable which will hereinafter be described BODY code See the surface card section in the MCNP manual px cs tr etc Number of parameters Number of parameters required in defining a BODY refer to the MCNP manual Parameter Parameters are described with a combination of value s and or variable s which will hereinafter be described A variable must be identified with a symbol at the head CELL count2 2 Number of CELLs to define Material File Parameter imp p imp e kind kind 1 Region Out 0 C
34. E 00 5 4 143 24 25 B 141 8 6 15 16 impzp 1 000 impie 1 000 3 485 0 375 6 96000E 00 10 9 171 9 4 16 171 E 0 1 05 2 Impip 1 000 impie 1 000 00 1 05 2 11 3 18 H te 3 ta 5 impzp 1 000 imp e 1 000 1 74000E 00 18 19 11 3 SE nn impzp 1 000 impie 1 000 ho material cards mW 1 85000E 00 3 2 19 RRR impip 1 000 imp e 1 000 1 20490E 03 11 2 13 20 impip 1 000 impie 1 000 na materiali copper 1 19000E 00 i2 1 20 7 011 1 20 211 29000 1 0000000E 00 impzp 1 000 imp e 1 000 333 437 0 53337 0 6 a2 0 5 ae 0 6 no material germanium 2000 1 0000000E 00 supere Ln un E eE cE CE E cE cE CE E cE cE CE GE ch CE E eE cG Hh surface card for geometry HH no 3 material magnesium supp poppe pese 12000 1 0000000E 00 na 4 material beryl ium 4000 1 0000000E 00 Pz Fe 0 1 no 5b material air Pe 0 15 1000 1 0000000E 05 6000 1 2154000E 04 Pz 0 45 T000 7 54780000E 01 8000 2 3233000E 0 1 Pz 0 45003 18000 1 2834000E 02 Pz 1 05 PZ 52 005 B material PMM Pi 8 43 54182 E 02 6000 5 3384027E 01 Pz 10 04 1561782E 0 Pz 10 13 Pz 11 Oo DO cO J 32 cn a c2 r3 5 Button in toolbar Display cross section Users can view a graphic representation of geometric models they have created A cross section view will appear in a new window after clicking the Display cross section button This is done by the MCNP geometry plotter with the ip
35. JAEA Data Code CREPT MCNP 1 1 Calibration Code for the Representative Point Method with MCNP User Manual Version 1 1 0 Jun SAEGUSA Department of Radiation Protection Nuclear Science Research Institute Tokai Research and Development Center October 2008 Japan Atomic Energy Agency gt PTA a gt zi C e CD http www jaea go jp T319 1195 2 4 029 282 6387 Fax 029 282 5920 E mail ird support jaea go jp This report is issued irregularly by Japan Atomic Energy Agency Inquiries about availability and or copyright of this report should be addressed to Intellectual Resources Section Intellectual Resources Department Japan Atomic Energy Agency 2 4 Shirakata Shirane Tokai mura Naka gun Ibaraki ken 319 1195 Japan Tel 81 29 282 6387 Fa
36. a Geometry Menu By clicking the button on the right side of the blank line users can browse and select the necessary file Users are strongly recommended to check over that the position and size of a volume sample and detector in the selected file coincides with the geometries which are used in the calculation of the efficiency curves group A and in the volume sample mentioned in the following 3 Confirm that in the case users use a tray for a measurement of a volume sample the tray should be removed or filled with air for a calculation without sample material and without container unless the tray is included in the calculation geometry for obtaining the efficiency curves group A 3 File name volume sample A file containing the data of volume sample volume source should be selected The file is created in the Data Volume sample Menu By clicking the button on the right side of the blank line users can browse and select the necessary file Users are strongly recommended to check over that the position and size of a volume sample and detector coincides with the geometries which are used in the calculation of the efficiency curves group A 4 Data grid Arbitrary uncertainty Each calculated efficiency value is accompanied by its statistical uncertainty which is automatically estimated by the MCNP code There is however the non statistical uncertainty other than the statistical one The non statistical
37. alculate Region 1 Detector tally 2 Detector 3 Cover In 4 Cover it 5 Tray 6 Jig 7 Object 8 Vessel 1 smm0y2 2 5 1 0 1 0 2 2 JAEA Data Code 2008 017 Smn1 1 4 6 1 0 1 0 2 Definition of CELLs CELL has basically the same meaning with the cell used in MCNP Data of CELL must be arranged in sequence on one line per single CELL in the order of the material file name parameter imp p imp e kind the meanings of the imp p imp e kind are described hereinafter These parameters are delimited by commas Material file name Assign a variable which 1s defined in the last part of this file If this part is left blank the material is unconditionally regarded as being VOID Parameter Parameters are described by the combination of the BODY numbers defined above Also refer to the cell card section in the MCNP manual Variable s must not be used here imp p Assign the importance refer to the MCNP manual if needed of photons Normally this value should be 1 0 but can be 0 0 if photons are not transported in the CELL imp e Assign the importance refer to the MCNP manual if needed of electrons Normally this value should be 1 0 but can be 0 0 if electrons are not transported in the CELL kind Assign a type of the CELL The type should be selected from the following list Out of the calculation area See the Data Calculation area Menu This selection can be made only for the bas
38. alculation Results Detailed contour map of parameter 7 around a representative point Menu In this menu a detailed contour map of parameter 7 which is calculated in the Calculation Efficiency curve for volume sample without self absorption representative point Menu is displayed in an R Z graph In the graph a region which is occupied by a detector or a cover if present is blacked out Displayed range in the R and Z directions 1s limited to within 2 cm from a representative point HE Contour map of parameter t x File output Close Select data for display File name representative point GE 3air Representative point and parameter t A 3 620 em 6 300 cem T 22 75e 003 1 0E 00 B 3E 00 5 9E 01 3 5E 01 2 0E 01 1 2E 01 UE 02 4 1E 02 2 AE U2 1 4E 02 8 4F 3 4 3E 03 256 03 1 7E D3 m 1 0E 03 43E 00 1 7E 00 5 6E 00 1 File name representative point A file containing calculated results of the representative point should be selected By clicking the button on the right of the blank line users can browse and select the necessary file 2 Representative point and parameter t The values of a calculated representative point and parameter t at the point are displayed 3 Button File output Users can refer the 7 values by pressing this button The output file includes a data group of R Z f in a tabular format R and Z are limited to 2 cm from a representative
39. among the efficiency values typical interval 1 mm An efficiency curves group containing tens of thousands of n E r z values is obtained through the interpolation The efficiency curves group data is then averaged on the space which should be occupied by the volume sample to be measured as eap Meath ry dz 1 where ME corresponds to the efficiency of a cylindrical sample with height h and radius R The resulting efficiency curve is compared with each curve included in the efficiency curves group To find out the representative point the degree of agreement between the two curves is estimated by the following parameter i r Z where n is the total number of the energy points and u is the uncertainty of D E The position P r z where f r z gives the minimum value is defined as the representative point P rrp zrp Typical values of the smallest 7 r Z are found elsewhere S200 Step 2 The single point calibration at the representative point gives a comparable efficiency curve with that of the volume sample measured although the measured efficiency curve at the representative point does not take into account the radiation absorption in the sample container and the self absorption in sample material For the setting of a standard point source at a representative point the use of a special apparatus as shown in Photo 3 2 may be helpful JAEA Data Code 2008 017 dh je Hx f Standard point d E source
40. arts were changed users must click the buttons and reselect the file to reflect the changes in the geometric model 2 Tab Offset value The positional relationships among the selected parts are set with the Offset value tab There are a total of eleven parameters but only those related to the selected parts are listed in the data grid The eleven parameters are as follows 1 Z position of top surface of cover Default value 0 0001 2 Gap between cover and detector Default value 0 3 Gap between cover and support jig Default value 0 4 Gap between cover and measured sample Default value 0 5 Gap between tray and cover Default value 0 6 Z position of top surface of detector Default value 0 0001 7 Gap between detector and measured sample Default value 0 8 Gap between tray and detector Default value 0 9 Gap between support jig and detector Default value 0 10 Gap between tray and measured sample Default value 0 11 Z position of top surface of tray Default value 0 0001 Ensure that the Z position of a selected part has been correctly set so that the detector locates the same position between when the efficiency curves group is to be calculated and when the self absorption correction factors are to be calculated 3 Tabs Measured sample Support jig Tray Cover Detector Calculation area The parameters and their values are listed for reference Users can change these parameter va
41. ary file The parameter values of the default support jig are then modified to specify the intended support jig The default style itself cannot be modified in the GUI window but it can be modified or newly added in a text file The description format of the text file is given in Appendix A 8 Originally the CREPT MCNP code has an annular support jig as a default style The geometry of the support jig is shown schematically in Fig 2 6 along with its parameters and default parameter values in Table 2 6 JAEA Data Code 2008 017 e 5 e 4 e 3 1 6 Fig 2 6 Half sectional view of a default support jig Table 2 6 Parameters data type and parameter values of the default support jig File name annular csv Parameter Datatype Default 3 int F int Mid radius of support jig cm Floating poin Outer radius of support jig cm Material of support jig JAEA Data Code 2008 017 2 5 2 6 Data Measured sample Menu A measured sample consists of sample material sample matrix and a sample container It is modelled in order to calculate the self absorption correction factors Usually users create two types of measured sample in obtaining an efficiency curve One is with sample material and with sample container and the other is without either of them With this version of the code the shape of sample is limited to rotationally symmetrical ones 8 object
42. aterial of volume sample Chater JAEA Data Code 2008 017 H 2 1 10 9 b 3 E J 5 8 7 Fig 2 8 Half sectional view of a default Marinelli shaped sample Table 2 8 Parameters data types and parameter values of the default Marinelli shaped sample File name Marinelli csv Parameter Dattype Default I Height of volume sample em Floating point 89 Q Height of sample container em Floating point 89 9 Material of sample container Character 10 Material of volume sample Chater JAEA Data Code 2008 017 2 5 2 7 Data Calculation area Menu Users need to specify calculation area which denotes the region in which a detector and all of other parts i e the cover tray support jig and measured sample are encompassed In that region photons are transported with MCNP Parameters to specify the area and its filling material are assigned on the following window E space window for data originationz3 rl 7 csv 1 Default A default calculation area is selected by clicking the button on the right side of the blank line Users can browse and select the intended file The parameter values are then modified to specify the intended region The default style itself cannot be modified in the GUI window but it can be modified
43. cecocececeseceocesceocescecoeeo 59 DHA TIT 7 1 JWODTEK ore ee ee ee en ee en oe en oen eene eene 60 AL A 60 AO SENSE BUSH Ag yh ei iae 61 A3 FSSA ES LOO a Fe aipee 62 A4 mmm 65 BS NR EMT 66 AG duh DE Cee A ieee 67 A7 SR IES SF FIT Wu aa 68 v4 n M 69 JAEA Data Code 2008 017 Disclaimer amp Intellectual Property Statement CREPT MCNP is a calculation code for use in carrying out efficiency calibrations with the representative point method The code can be found in the PRODAS database administered by the Center for Computational Science amp e Systems Japan Atomic Energy Agency Users must obtain the code through the center and use it in compliance with the administrative computer program rules set by the center The CREPT MCNP code is provided free of charge to the academic research community or public organisations for non commercial non profit internal research use Prior to use of the code users will need to individually obtain and install the MCNP code as it is not included with the CREPT MCNP code Note that neither the author or any Japan Atomic Energy Agency member can be held responsible for results obtained using the code and or that the representative point method will meet the users requirements nor any damage or loss resulting from its use A request
44. completed output file located in the work effA directory and allows users to resume any calculations which has been accidentally or purposely suspended 5 Number of particles The number of source particles per batch refer to the following 6 and 7 for more details on the batch is set in the textbox The default value is 100000 6 Statistical accuracy termination condition Assign the statistical accuracy to terminate a calculation An MCNP calculation is carried out for obtaining a peak efficiency at each lattice point or at the additional coordinate point and for each energy point but the calculation actually consists of several sub calculations which are segmented into source particles batches That is the sub calculations are automatically repeated until the statistical accuracy 1s equal or less than the assigned value The default value is 0 01 7 Maximum calculation time min Assign the maximum calculation time to terminate a calculation This option is useful for calculations that users expect long calculation time to reduce the statistical accuracy such as those with predominant interactions between photons and high shielding material A calculation consists of several sub calculations which are segmented into source particle batches Sub calculations are automatically repeated until the calculation time reaches the assigned value In other words it automatically stops once the time has been reached irrespective
45. e collection in Monte Carlo simulations of the efficiency of well type Ge detectors Nucl Instrum Meth A498 pp 300 351 2003 Institute of Electrical and Electronics Engineers IEEE IEEE Standard Techniques for Determination of Germanium Semiconductor Detector Gamma Ray Efficiency Using a Standard Marinelli Re entrant Beaker Geometry ANSI IEEE Std 680 USA 1978 P N Johnston M Hult and J Gasparro Cascade summing effects in close geometry gamma ray spectrometry Appl Radiat Isotopes 64 pp 1323 1328 2006 K Kawasaki K Mochizuki T Suzuki and N Kinouchi Renewal of centralized radioactivity measurement system for radiation control JAERI Tech 2004 070 Japan Atomic Energy Research Institute Tokai Japan 2004 in Japanese T Nakamura and T Suzuki Monte Carlo calculation of peak efficiencies of Ge Li and pure Ge detectors to voluminal sources and comparison with environmental radioactivity measurement Nucl Instrum Meth 205 pp 211 218 1983 T Oishi M Yoshida J Saegusa T Honda K Takahashi and H Kuwabara Determination of detection efficiency curve for a gas monitor with a built in germanium detector J Nucl Sci Technol 38 pp 203 208 2001 S B Samat Y Oi M Taki I Manabe M Yoshida and K Minami Characteristics of prepared gamma ray calibration sources for radioactivity measurement of environmental and radiation control samples JAERI Tech 95 010 Japan Atomic Energy Research Institute
46. e sample GE3 70H csv E Definition of a volume sample GE3 70H csv JAEA Data Code 2008 017 1 Tab General Configuration of a source In this version of the code only a cylindrical volume sample with its axis coinciding with the detector axis and of homogeneous material can be treated Users therefore should select Cylinder on z axis uniform distribution 2 Tab Configuration Number of volume source s Users will not be able to change this number if Cylinder on z axis uniform distribution was selected at the Configuration of a source item in the General tab 3 Tab Configuration Data grid Users should provide a radius and positions in Z direction of a cylindrical volume sample from which photons will be emitted refer also to 4 4 Tab General Checkbox Particles emitted from overlapped area Should be checked when users intend to make photons be emitted from an overlapping region by a cylindrical region set with the Configuration tab and by a measured sample which is set with the Data Measured sample Menu Examples of this concept are schematically shown in Fig 2 10 In the case the cylindrical region is larger than the measured sample as in pattern A of the figure the source region will be identical to the measured sample If the cylindrical region does not encompass the measured sample as in pattern B then the source region 1s the region that overlaps the two reg
47. e sample Relative uncertainty efficiency at a representative point Relative uncertainty Maximum difference of efficiencies between that of at a representative point and at each position within R CHK SPH absolute value RE E map data Z R O DODOD 0 10000 12 00000 1 0000R426 4 0000Ef29 1 11 90000 1 0000E5ET28 1 0000EBT29 1 11 90000 1 0000ET29 1 0000BT29 1 Map of parameter on the R Z plane snip map data R A 000000 Os 10000 12 00000 1 0000ET28 1 0000E8BT29 1 211 90000 1 0000H 26 21 0000EL206 1 11 90000 1 0000ETZ29 l1 0000ER429 1 11 70000 1 00000E 28 1 0000E5428 1 JAEA Data Code Map of parameter 7 on the R A plane snip 2008 017 0 20000 0000E 728 0000E 28 0000E 28 0 20000 UOOD0ETZO 0000E428 0000E 28 0000E 728 JAEA Data Code 2008 017 A 4 Output File for the Efficiency Curves Used for Self Absorption Correction 66499 This type of file is stored in the work selfsheild folder Any line beginning with a means a comment line Model getbox Source getbox exp NPS 10000 Precision 0 05 MaxTime 0 Lines beginning with a cannot be removed They are used in the system EnergyCount 12 Number of energy points Energy MeV Efficiency Uncertainty Arbitrary uncertainty 0 06000 3 89e 003 0 04820 0 00000 0 08800 1 16e 002 0 04620 0 00000 0 12200 1 528 002 404650 0 00000 0 16600 1 48e 002 0 0471
48. ecause they will give the same result By clicking the button on the right side of the blank line users can browse and select the necessary file Users are strongly recommended to check over that the position and size of a volume sample and detector in the selected file coincides with the geometries which are used in the calculation of the efficiency curves group A and with the volume sample mentioned in 9 In the case the Particles emitted from overlapped area checkbox see Data Volume sample Menu was checked when the volume sample file was created this option 9 calculation geometry is not activated 10 Output file name data of representative point An output file name must be assigned by clicking the button on the right side of the blank line The extension for this type of file is out 11 Checkbox Specification of a cut plane for distribution of t This option is not currently available Leave unchecked 12 Button Run A calculation starts by pressing the run button It will typically take a few minutes to finish if both files 8 volume sample and 9 calculation geometry are involved but less if only 8 volume sample file is used for discrimination of a source region from the efficiency curves group C JAEA Data Code 2008 017 2 5 3 3 Calculation Efficiency curve for a volume sample with and without self absorption Menu With this menu a series of Monte Carlo calculations is ca
49. ement of the sample container JAEA Data Code 2008 017 Parameter count2 5 Number of variables to define Variable Name Comment Type Default pos Distance from surface Z O cm to basal surface of sample FES 0Lcm cm DBL 0 0 The variable pos must be given except in the case that this file is for defining the calculation area It is a variable to set a reference position of a basic element The reference position differs depending on the basic element which must be selected from the following list Type and Default must invariably be DBL and 0 0 respectively 1 Detector Top surface of a detector 2 Cover Top surface of a cover 3 Tray Top surface of a tray 4 Support jig Top surface of a support jig 5 Measured sample A surface which comes in contact with a detector cover or tray normally a basal surface of a sample container thick Thickness of tray cm tL 1 Oop om DBL 1 0 0 The variable thick must be given in the case that this file is for defining the cover tray or support jig It is used as a variable to set an offset value between basic elements of different types Type and Default must invariably be DBL 1 and 0 0 respectively 1 Cover Thickness top end of a cover 2 Tray Thickness of a tray 3 Support jig Gap in Z direction between top surface of a detector and inner surface of a cover
50. es group C Position of a representative point selected from the data of efficiency curves group B 8 Calculation of an efficiency curve for volume sample without self absorption parameter t and determination of Pi E33 1 File name efficiency curves group A A file containing the data of efficiency curves group A should be selected The file can be created in the Calculation Efficiency curves group A Menu By clicking the button on the right side of the blank line users can browse and select the intended file JAEA Data Code 2008 017 2 Number of partitions for R A division number should be provided to calculate the data of the efficiency curves group B from that of the efficiency curves group A For example in the case the number of the partitions which is set in the Data Alignment of point source Menu is 9 and this value is 20 the lattice points for the efficiency curves group becomes 161 9 1 x20 1 The default value is 20 3 Number of partitions for Z Same as above 4 Checkbox Save data of efficiency curves group Users should check the checkbox if they want to keep the data of efficiency curves group B in a file In the case an output file name must be assigned by clicking the button on the right side of the blank line 5 Hidden menu File name angular dependence of efficiency This option cannot currently be used Select nothing 6 Number of sub partition
51. essful go to the step 3 otherwise step 2 This setup requires the WET Framework version 1 1 4322 Please install the NET Framework and run this setup again The NET Framework can be obtained from the web Would you like ta do this now 2 Double click the dotnetfix exe icon on the installation CD to install NET Framework 1 1 Note that the dotnetfix exe file on the CD is not the latest version JAEA Data Code 2008 017 3 When the following window appears click the Next button Welcome to the crept Setup Wizard 4 Select a folder directory in which to install the code Select whether a user or users can run the code and then click the Next button Select Installation Folder JAEA Data Code 2008 017 5 When the following window appears click Next to commence installation Confirm Installation Installation Complete JAEA Data Code 2008 017 2 3 Directory Configuration Execution of the code will automatically create the subdirectory structure shown in Fig 2 1 within the directory designated in step 4 of the previous section RR cae HEP teanaseeaenecessssabassesansnesesesslecesscssesmaseerinessuvasnosssecsers Stores main program dll files and help files Stores data required for system execution lib PEEL TT Stores dummy libraries used in chkregion exe 1 Stores data of default parts stylised detectors samples ete RON Stores data of default
52. fficiency curve RI Efficiency curves group A R2 Efficiency curves group B R3 Comparison of efficiency curve at a representative point and that of volume sample without self absorption R4 Contour map of parameter t R5 Detailed contour map of parameter 7 around a representative point R6 Comparison of efficiency curves of a volume sample by means of point integration and by MCNP R7 Final efficiency curve W1 W4 Align in tiles in piles horizontally vertically H1 Help H2 System version Example of function Remarks MCNP path setting Material registration Geometric definition for each part Positional relationship between the parts Coordinates and intervals for point source alignment Efficiency curves of a volume sample by means of point integration Efficiency curve at a specified position is depicted graphically For cross checking JAEA Data Code 2008 017 2 5 Operation Menus 2 5 1 File Menu 2 5 1 1 File Setting Menu Environmental settings required for operation are given in this menu System setting 1 Language Select either English United States or Japanese Japan environment from the drop down list Note that users can change the language whenever they need 2 MCNP file path A directory that includes the MCNP execution file need to be designated By clicking the button on the right side of the line users can browse and select the necessary directo
53. heet JAEA Data Code 2008 017 2 5 4 3 Calculation Results Comparison of efficiency curve at a representative point and that of volume sample Menu With this menu users can compare two types of efficiency curves one being a calculated efficiency curve at the representative point red curve in the figure while the other is that of a volume sample without any self absorption effect blue curve Both curves are determined through the data of efficiency curves group C The two curves should have similarity in their shapes and magnitudes Degree of agreement between two curves means the minimum f 96 If these curves do not show similarity the user should check over the source conditions Both the horizontal axis photon energy and vertical axis peak efficiency are in logarithmic scales Users cannot change ranges of these scales However if needed users can export the data to a Microsoft Excel spreadsheet HE Graph of efficiency curve Op Call EXCEL Close Select data far display File name representative point GE 3air a Efficiency Efficiency curve at R 3 620 lt 6 300 Efficiency curve by point integration of efficiency curees group 1 00 Energu M ev 1 File name representative point A file containing calculated results of the representative point should be selected By clicking the button on the right side of the blank line users can browse and select the intended file 2 Butto
54. hould be selected By clicking the button on the right side of the blank line users can browse and select the necessary file 2 File name efficiency curve for volume sample without material container A file containing the efficiency curve data of a volume sample without material and without container should be selected By clicking the button on the right side of the blank line users can browse and select the necessary file JAEA Data Code 2008 017 3 Button Call EXCEL By clicking this button the efficiency data and graph can be exported to a Microsoft Excel spreadsheet 2 5 4 7 Calculation Results Final efficiency curve Menu Users can plot on a graph the efficiency curve which was determined by the representative point method final efficiency curve shown in blue line In the graph a measured efficiency curve red curve at a representative point is also shown for comparison Both the horizontal axis photon energy and vertical axis peak efficiency are in logarithmic scales Users cannot change the ranges of these scales However if needed users can export the data to a Microsoft Excel spreadsheet HE Graph of efficiency curve Me Call EXCEL Close Select data for display File name efficiency curve for volume sample with material container 8E3 finals Efficiency Efficiency curve of standard paint source at representative paint Final efficiency curve Energu M ev
55. ic element of the calculation area 0 The calculation area See the Data Calculation area Menu This selection can be made only for the basic element of the calculation area 1 Detection part See the Data Detector Menu This selection can be made only for the basic element of the detector This part is regarded as the tally cell in MCNP 2 Detector part See the Data Detector Menu This selection can be made only for the basic element of the detector The detector part other than the detection part should be set as 2 3 Inside cover See the Data Cover Menu This selection can be made only for the basic element of the cover The detector part detection part and the support jig part are automatically removed from this region when each part is assembled geometrically 4 Cover See the Data Cover Menu This selection can be made only for the basic element of the cover The cover part other than the inside cover should be set as 4 5 Tray See the Data Tray Menu This selection can be made only for the basic element of the tray 6 Support jig See the Data Support jig Menu This selection can be made only for the basic element of the support jig 7 Measured sample See the Data Measured sample Menu This selection can be made only for the basic element of the measured sample 8 Sample container See the Data Measured sample Menu This selection can be made only for the basic el
56. ight side of the blank line and users can then browse and select the necessary file The parameter values of the default cover are then modified to specify the intended cover And while the default style itself cannot be modified in the GUI window it can be modified or newly added using a text file of which the format is given in Appendix A 8 Originally the CREPT MCNP code has a cylindrical closed end cover as a default cover The geometry of the cover is shown schematically in Fig 2 4 along with its parameters and default parameter values in Table 2 4 4 3 1 6 5 2 Fig 2 4 Half sectional view of a default cover Table 2 4 Parameters data type and parameter values of the default cover File name cover csv Parameter Datatype Defaut Thickness of cover top cm Floating point 02 Length of cover cm Floating point 12 Inner radius of cover cm Floating point Outer radius of cover cm Floating point 5 Materialofcover Character 6 Filling material of space laying inside cover 0 2 12 2 3 8 JAEA Data Code 2008 017 2 5 2 4 Data Tray Menu Tray is another part around a detector and may be used as a stage to set a sample to be measured above the detector Parameters to specify the geometric configuration and material of the tray can be assigned in the following window E tray window for data origination3mm csv
57. int in a short amount of time once the efficiency curves group the data group characterizing a spatial distribution of the detection efficiencies around a detector has been calculated and stored The code can deal with a cylindrical or Marinelli shaped sample in which radioactivity is homogeneously distributed The efficiency calibration with this code makes quantification of radioactivity smoother It also contributes to reducing radioactive waste because the method does not need any standard volume sources It can be utilized in measuring radioactivity promptly and nondestructively for a broad range of volume samples Acknowledgements The author would like to thank Mr A Takamura and Mr T Sugita of the Science and System Laboratory Ltd for the elaborate programming of the code JAEA Data Code 2008 017 References Br00 CY08 FU89 He03 IE78 Jo06 Ka04 Na83 Oi01 Sa93 Sa00 Sa04 Sa08 XM05 J F Briesmeister ed MCNP A General Monte Carlo N Particle Transport Code version AC Radiation Safety Information Computational Center RSICC Oak Ridge National Laboratory LANL Manual LA 12625 M Version 4C Los Alamos USA 2000 Cygwin homepage http www cygwin com accessed Feb 2008 Fujitsu Limited SSL II User s Guide Scientific Subroutine Library First edition 99SP 4020E 1 online available 1989 F Hernandez and F El Daoushy Accounting for incomplete charg
58. int of origin R cm Point of end R cm Point of origin Z cm Point of end Z cm Precision of a point source setting cm Lf iz ECLE daiz Cl iZ 39 224 3262000 6 30000 2 7539E 03 Lattice number of a representative point R Lattice number of a representative point Z R coordinate of a representative point cm Z coordinate of a representative point cm Parameter 7 0 01 ENERGY AVR DATA AVR ERROR POINT DATA P ERROR SPH ERROR Z2 2000H 02 2 5914E 02 2 1556E 02 2 5079 amp 5 02 L 9031E 02 0 0000E8T00 6 0000E 02 2 775 H 02 2 0879E 02 12 78705 02 1 8384E 02 0 0000H 00 9 9000E 02 2 7190E 02 2 1097E 02 2 73135 02 1 9442E 02 0 0000E700 l 2200E S01I 2 5577B DZ2 ZXL LIES02 24 5054E U02 1 91235 072 Q DOODET O 1 06600E 01 2 2543E 07 2 1355E 02 2 27L0E 02 2 0151E 02 0 0000ET00 2 1900E 01 1 5996Eb 07 12 2907Bb 02 1 6L195 02 2 4509E 02 0 0000ET00 2992008 01 L 2097E 07 2 22415 02 1 19014E5 02 Z 24l115E 02 0 000025T00 9 14005 01 9 7761E 05 2 2039E 02 9 0563145 05 2 2593E 02 0 0000ET 00 6 60200E 0l 8 03596b 05 2 3424015E 02 T7 9396E 05 2 43378 02 0 00008T00 8 9800E 01 6 5115E 03 212 4094E 02 6 5036H 03 12 4656E 02 0 0000E 00 1 1730ET00 5 23705E 053 2 4398E 02 5 4267E 053 2 4018E 02 0 0000ET00 1 33590EbT00 4 9501E 05 2 3579E O02 4 9166E 09 2 2559E 02 0 0000ET00 1 8360E 00 4 2566E 03 2 4589E 02 14 3054E 03 2 3493E 02 0 0000E 00 Energy MeV Spline interpolated efficiency of a volume
59. ions In most cases users will set the source region as in pattern A and note that they have provided the parameters for the cylindrical region that are the same or somewhat larger but not that larger than the measured sample Such settings will help improve the computational efficiency of sampling a source position with the Monte Carlo calculation 5 Tab General File name energy points A file defining a data group of source energy points should be selected by clicking the button on the right side of the blank line The file can be created with the Data Source energy point Menu and users can browse and select the created file 6 Tab Configuration Number of volume source s In this version of the code users cannot change this setting if Cylinder on z axis uniform distribution was selected in the Configuration of a source item of the General tab JAEA Data Code 2008 017 Measured volume sample Measured volume sample Cylindrical region Cylindrical region Source region Source region shaded shaded Pattern A Pattern B Fig 2 10 Half sectional view of the positional relationship of the cylindrical region and measured sample JAEA Data Code 2008 017 2 5 2 11 Data Alignment of point source Menu In this menu a group of grid points lattice points is set for obtaining efficiency curves group A The lattice points distributes aro
60. lues temporarily using these tabs but the change or changes are not reflected in the original data which has been stored in the Work parts folder JAEA Data Code 2008 017 2 5 2 9 Data Source energy point Menu In the Data Source energy point Menu a data group is set in terms of energy points for a virtual multi energy photon source and of the region of interest ROI for detections of photons at a detector E Data of energy points 22to1l836_cs Lows sar doe 1 Number of energy points Assign the number of energy points to be used in the MCNP calculations The number of rows in the data grid will change in relation to that number 2 Energy region of interest The energy region of interest ROT is a region related to the pulse height spectrum tally the F8 tally in MCNP Default value for the energy ROI is 8 For example in the case the value is set at 8 9o a photon with initial energy 1 MeV will be tallied if it has deposited energy between 0 92 and 1 08 MeV on a detector The value will be used with each individual energy point 3 Energy MeV Photon energy points in MeV units must be assigned in ascending order The energy points must be between 0 01 MeV and 10 MeV JAEA Data Code 2008 017 2 5 2 10 Data Volume sample Menu The conditions of a volume sample source conditions are set in order to estimate the self absorption correction factors W Definition of a volum
61. n Call EXCEL By clicking this button the efficiency data and graph can be exported to a Microsoft Excel spreadsheet JAEA Data Code 2008 017 2 5 4 4 Calculation Results Contour map of parameter t Menu In this menu a contour map of the parameter t which is calculated in the Calculation Efficiency curve for volume sample without self absorption representative point Menu is displayed in an R Z graph In the graph a region which is occupied by a detector or a cover is blacked out HE Contour map of parameter t B x File output Close Select data for display File name representative point GE 3air Representative point and parameter t A 3 620 em 6 300 cm T 22 75 003 1 0E 01 1 6E 01 e 2 4E 00 1 2E 00 5 9E 01 2 SEIT 1 4E 01 PDFE D2 3 BE D2 1 7E 02 amp 4E 03 A1E 03 20E 03 m 1 0E 03 1 2E 01 D DE 00 1 6E 01 1 File name representative point A file containing calculated results of the representative point should be selected By clicking the button on the right side of the blank line users can browse and select the intended file 2 Representative point and parameter t The values of a calculated representative point and parameter t at the point are displayed 3 Button File output Users can refer the 7 values by pressing this button The output file includes a data group of R Z f in a tabular format JAEA Data Code 2008 017 2 5 4 5 C
62. oactivity are prepared Reliable peak efficiency curves can be obtained by providing the standard volume source which has identical characteristics with the volume sample to be measured However in its implementation phase there arise some problems 1 It is not always easy to prepare a lot of standard volume sources each of which has the same shape composition and density with that of a measured sample In the Nuclear Science Research Institute NSRI of the Japan Atomic Energy Agency JAEA only limited types of standard sources as shown in Photo 3 1 have been prepared Manufacture of these sources requires skillful techniques Sa95 Ka04 2 The efficiency calibration with a standard volume source that does not fit the measured sample causes undesirable results Especially the impact is not negligible for lower energy photons below 100 keV due to difference of the self absorption effect between the standard source and a measured sample 3 In general the standard sources includes short lived radionuclides such as Cr half life 27 7 days and Sr half life 64 8 days The working lifetime of the sources therefore is two years at the longest The preparation of the sources must be repeated and this leads to the increase of radioactive waste when the sources are useless The second method the analytical calculation is sometimes referred as the extended source method It is usually based on a combination of some form
63. of end cap cm Floating point 8 MaterialofGecrystal o haacter 9 Material ofcontactpin Character 10 Materialofmount cup Character 11 Matrialofendcap Character JAEA Data Code 2008 017 4 3 5 20 19 17 12 1 7 T 8 9 Fig 2 3 Half sectional view of a default n type HPGe units in cm Table 2 3 Parameters data type and default parameter values for an n type HPGe File name ge TypeN csv Parameter paatype Default Length of end cap cm Floating point 11 Distance from upper surface of detector case to upper surface of Ge crystal cm Length of Ge crystal cm 7 6 Distance from upper surface of Ge crystal to tip of contact pin cm Length of mount cup cm Floating point Thickness of dead layer cm 0 00003 Thickness of end cap cm 0 1 0 03 0 2 10 0 05 11 0 1 12 0 1 Outer radius of Ge crystal em Outer radius of protector em Floating point 0 45 Floating point 2 47 13 Outer radius of Ge crystal cm 2 92 14 Outer radius of protector cm 3 73 15 16 17 Material of end cap 18 Material of window 19 20 Material ofprotector Character JAEA Data Code 2008 017 2 Data grid Parameter Parameters which constitutes a detector are listed Users cannot change add o
64. of the statistical accuracy value set in 6 The default time value is 0 and in this case a calculation stops based only on the statistical accuracy Note that the maximum calculation time must be set for one MCNP calculation through which an efficiency value for a point source with photon energy E located at P r z is obtained 8 Output file name efficiency curves group A An output file name must be assigned by clicking the button on the right side of the blank line Users can browse and select an existing file in the case the Recalculate checkbox is checked otherwise a new file name must be given The extension for this type of file is out JAEA Data Code 2008 017 9 Button Run or Stop By pressing the run button users can start or resume a series of calculations Progress of calculations is displayed in the window Users can suspend a series of calculations by pressing the stop button 2 5 3 2 Calculation Efficiency curve for volume sample without self absorption representative point Menu The main purpose of this menu is to calculate the following data based on the data of the efficiency curves group A Efficiency curves group B Spline interpolated data of the efficiency curves group A Efficiency curves group C finely Spline interpolated data of the efficiency curves group A Efficiency curve of an air equivalent measured volume sample volume weighted average of the efficiency curv
65. on SA correction factors Stores results final efficiency data M MED E Stores efficiency data of volume sample with without SA effect Stores data of source energy es Stores data of spatial alignment conditions of a point source EErEE EE Stores data of source conditions for a standard volume source Fig 2 1 CREPT MCNP Directory structure JAEA Data Code 2008 017 2 4 Basic Operation Run crept exe by clicking its icon or the equivalent shortcut icon on the desktop and the main window will appear All CREPT MCNP code functions can be accessed through the main menus on the menu bar at the top of the main window Et CREPT MCNP1 1 E The code has six main menus Each of them has several sub menus as summarized in Table 2 1 More details on them are given in section 2 5 Main menu File F Data D Calculation C Calculation Results R Window W Help H JAEA Data Code 2008 017 Table 2 1 List of CREPT MCNP code menus Sub menu F1 Setting F2 Exit DI Material D2 Detector D3 Cover D4 Tray D5 Support jig D6 Measured sample D7 Calculation area D8 Geometry D9 Source energy point D10 Volume sample D11 Alignment of point source C1 Efficiency curves group A C2 Efficiency curve for volume sample without self absorption representative point C3 Efficiency curve for volume sample with and without self absorption C4 Final e
66. option and while X Windows is being used the plot window supports a variety of interactive features refer to the MCNP Manual XM05 When version 5 of MCNP and Cygwin CY 0 are being used X Window needs to be launched before the Display cross section button is clicked To activate the window in brief 1 run Cygwin by double clicking its icon 2 type the startx command in the Cygwin console window and 3 click the tab blinking at the bottom of the PC screen When version 4 of MCNP is being used there is no need to start the X Window system This rule also holds true for the Data Cover Menu Data Tray Menu Data Support jig Menu Data Measured sample Menu and Data Calculation area Menu all of which will be described hereinafter JAEA Data Code 2008 017 ies PLOT WINDOW 02 12 08 15 06 39 probid 02 12 08 15 04 29 basis Hi 0 000000 1 000000 0 000000 0 000000 0 000000 1 000000 5 37 Value for cei in cell 2 5 2 3 Data Cover Menu Cover refers to one of the parts around a detector It might be used to protect a detector from radioactive contamination or physical damage Parameters to specify the geometric configuration and material of the cover can be assigned in the following window cover window for data originationPVCCover csv JAEA Data Code 2008 017 1 Default A default cover can be selected by clicking the button on the r
67. or newly added in a text file The description format of the text file is given in Appendix A 8 Originally the CREPT MCNP code has a cylindrical calculation area as a default style Geometry of the region is shown schematically in Fig 2 9 along with its parameters and default parameter values in Table 2 9 JAEA Data Code 2008 017 3 75400 on 4 V qn Fig 2 9 Half sectional view of a default style calculation area Table 2 9 Parameters data types and parameter values of the default calculation area File name cylinder csv Parameter Datatype Defaut Lower limit of region in Z direction cm Floating point Upper limit of region in Z direction cm Floating point Radius of calculation area cm Floating point Material of calculation area Character JAEA Data Code 2008 017 2 5 2 8 Data Geometry Menu In the Data Geometry Menu users can complete a geometric model used in the MCNP calculations This is done by selecting the parts used i e a detector cover and or measured sample etc and by providing positional relationships among the selected parts in the following window S Definition of calculation geometry NEW 1 Select parts Of the six different types of parts users must select those necessary to create a geometric model by checking the checkboxes and assigning necessary file names by clicking the buttons Note that because a
68. ption correction factor E Calculation of final efficiency curve 1 File name Efficiency curve of a volume sample with material container A file containing the efficiency curve data of a volume sample with both material and container should be selected By clicking the button on the right side of the blank line users can browse and select the necessary file 2 File name representative point A file containing calculated results of the representative point should be selected By clicking the button on the right side of the blank line users can browse and select the necessary file 3 File name measured efficiency A file containing measured efficiency curve data with a point standard source should be selected Users must prepare the file in the format shown in Appendix A 7 The file should be stored in the work meas folder and will appear through clicking the button on the right side of the blank line If the energy points in this file differ from those used in 1 or 2 the energy point group used in this measured data are adopted to the output file 4 This 1s done based on the Spline interpolation or extrapolation JAEA Data Code 2008 017 4 Output file name final efficiency curve An output file name must be assigned by clicking the button on the right side of the blank line The extension for this type of file is out 5 Efficiency curve of a volume sample
69. r remove these parameters items through the GUI window This rule is also applicable for the Data Cover Menu Data Tray Menu Data Support jig Menu Data Measured sample Menu and Data Calculation area Menu all of which will be described hereinafter 3 Data grid Value Users can modify the parameter values if necessary If the data type of a value is matter select it from the drop down list If no material is selected from the list 1 e blank the material is considered void in the MCNP calculations This rule also holds true for the Data Cover Menu Data Tray Menu Data Support jig Menu Data Measured sample Menu and Data Calculation area Menu all of which will be described hereinafter 4 Button in toolbar Show text file Clicking the Show text file button pops up the MCNP input file created by the code automatically It is helpful as reference although users cannot change the file in this window This rule also holds true for the Data Cover Menu Data Tray Menu Data Support jig Menu Data Measured sample Menu and Data Calculation area Menu all of which will be described hereinafter JAEA Data Code 2008 017 TEE pp ppp e tE cell card for geometry tf HEH pp ppp 8 85000ET00 2 3 12 Impip 1 000 imp e 1 000 ofa JaUB 7 13 EN 8 16 1 Impip 1 000 imp e 1 000 5 36000E 00 B 5 142 6 24 6 143 08 6 15 H 2 impzp 1 000 impie 1 000 5 36000
70. rameterization of a detector has been carried out carefully In short as each method has both merits and demerits the representative point method has been developed in consideration of these situations e er ei 2 E E r 5 N k b Es t _ E ES d m E ixl uo 4 a de v u Photo 3 1 Examples of the standard volume sources These sources are used in efficiency calibrations at the NSRI of JAEA The filling material is the foamed Portland cement 3 2 Efficiency Calibration with the Representative Point Method The representative point method is comprised of the following three steps 1 calculations to find the position of the representative point 2 single calibration at the representative point using a real standard point source and 3 correction of the self absorption effect to the efficiencies obtained in step 2 JAEA Data Code 2008 017 Step 1 The peak efficiency values nx E r z at multiple points P r z around a detector are calculated by means of the MCNP code E denotes the photon energy P r z locates on the plane r z coordinate that includes the central axis of a cylindrical detector The distances between two adjacent points are typically 20 mm The detection efficiencies are presumed to have symmetry about the detector central axis The Spline interpolation algorithm FU89 is introduced to provide the detailed spatial relation 7 7 z
71. rried out in order to obtain the self absorption correction factors This includes calculations of the The efficiency curve of a volume source with sample material and sample container The efficiency curve of a volume source without sample material and without sample container air equivalent sample Calculation of an efficiency curve of a volume sample GES 70Hepow Cem pexnMa ml Em joo se cotes poo Set Cea 002 oo 008 0022 OMD 0 010 0 010 0 010 0 010 0 010 0 010 0 010 LET pem 50000 1 File name calculation geometry with material container A file containing the data of calculation geometry for the calculation of the self absorption correction factor should be selected The file is created in the Data Geometry Menu By clicking the button on the right side of the blank line users can browse and select the necessary file Users are strongly recommended to check over that the position and size of a volume sample and detector in the selected file coincides with the geometries which are used in the calculation of the efficiency curves group and with the volume sample mentioned in the following 3 JAEA Data Code 2008 017 2 File name calculation geometry without material container A file containing the data of calculation geometry for the calculation of the self absorption correction factor should be selected The file is created in the Dat
72. ry 3 MCNP file name A name for the MCNP execution file need to be entered By clicking the button on the right side of the blank line users can browse and select the necessary file 4 Xsdir file path When version 5 MCNP is used leave this space blank Otherwise 1 e when version 4 MCNP is used the directory containing the xsdur file needs to be designated Clicking the button on the right side of the blank line allows users to browse and select the necessary directory JAEA Data Code 2008 017 5 Parameters for geometric visualization The CREPT MCNP code uses the X Windows system in illustrating a cross sectional view of the calculation geometries Check the box if you wish to be notified before geometric depictions are drawn on the display Leave it blank if using version 4 MCNP 2 5 1 2 File Exit Menu Selecting the Exit menu prompts the user a dialog box for a confirmation Select Yes on that box to exit Information LI E xit system OK e 2 5 2 Data Menu There are eleven sub menus in the Data Menu 2 5 2 1 Data Material Menu Materials used in each detector sample and sample container etc are defined with this menu Compositions and a density of each material are required for the definition These data are stored as a material database JAEA Data Code 2008 017 E Material and composition PHMA csv PMMA polymethylmethacrplate 1000 0 08054192
73. s for R An additional division number should be provided to calculate the data of the efficiency curves group C from that of the efficiency curves group A not B The number should be given to the lattice interval used in the efficiency curves group B For example in the case the number of the partitions of the efficiency curves group B is 161 and the value given is 10 the number of lattice points in the efficiency curves group C will be 1601 161 1 x10 1 The default value is 10 7 Number of sub partitions for Z Same as above 8 File name volume sample A file containing the data of volume sample volume source should be selected The file is created in the Data Volume sample Menu By clicking the button on the right side of the blank line users can browse and select the necessary file Users are strongly recommended to check over that the position and size of a volume sample and detector coincides with the geometries which are used in the calculation of the efficiency curves group A JAEA Data Code 2008 017 9 File name calculation geometry A file containing a data of calculation geometry for the calculation of the self absorption correction factor should be selected The file is created in the Data Geometry Menu Users will possibly find two types of files to select One is a file with sample material and the other is that without sample material air equivalent sample Users can select either b
74. system 1 Name R cm Z cm Energy MeV Efficiency Uncertainty detect 4 00000 12 00000 0 06000 0 03092 0 01770 detect 6 00000 12 000000 0 06000 0 01793 0023250 detect 8 00000 12 00000 0 06000 0 01144 0 02940 detect I0 00000 17 00000 0200000 0 008753 0 025370 detect 12 00000 12 00000 0 06000 0 00693 0 03790 detect 14 00000 12 00000 0 06000 0 00547 0 04260 detect 16 00000 12 00000 0 06000 0 00424 0 04850 detect 4 00000 10 00000 0 06000 0 05087 0 01370 detect 000000 L0 00000 006000 0 02075 002170 detect 8 00000 10 00000 0 06000 0 01249 0 02810 fThe 1 detect textis always printed The uncertainty is expressed in its relative value Data corresponding to a region occupied by a detector or a cover is not listed in this file JAEA Data Code 2008 017 A 2 Output File for the Efficiency Curves Group B 66499 This type of file is stored in the work effb folder Any line beginning with a means a comment line IMAX JMAX NE Lok 281 3 The number of coordinate points in the R direction the Z direction energy points ENERGY 6 0000E 02 8 8000E 02 1 2200E 01 Energy MeV lists as many as the number of energy points NE Z DATA R DATA DATA ERROR BAR 12 00000 0 00000 0 00000E 00 0 0000E 00 0 0000E 00 0 0000E 00 12 00000 0 10000 0 0000E 00 0 0000E 00 0 0000E 00 0 0000E 00 12 00000 0 20000 0 0000E 00 0 0000E 00 0 0000E 00 0 0000E 00 12 00000 0 30000 0 00000E 00 0 0000E 00 0 0000E
75. tomatically repeated until the calculation time reaches the assigned value In other words it automatically stops once the time has been reached irrespective of the statistical accuracy value set in 6 The default value for the time is 0 and in this case a calculation stops based only on the statistical accuracy Note that the maximum calculation time must be set for one MCNP calculation through which an efficiency value for a point source with photon energy located at P r z is obtained 8 Output file of an efficiency curve with material container An output file name must be assigned by clicking the button on the right side of the blank line The extension for this type of file is out 9 Output file of an efficiency curve without material container An output file name must be assigned by clicking the button on the right side of the textbox The extension for this type of file is out 10 Button Run A series of calculations starts by pressing the run button Progress of calculations is displayed on the window Users can stop the calculations by pressing the stop button but do note there is no recalculate option JAEA Data Code 2008 017 2 5 3 4 Calculation Final efficiency curve Menu In this menu the efficiency curve of a volume sample the final efficiency curve is calculated by multiplying the measured efficiency curve at the representative point by the calculated self absor
76. ulations that evaluate JAEA Data Code 2008 017 the self absorption correction factors and for the actual measurement at the representative point with a mixed radionuclide standard source 3 3 2 Uncertainty Estimation The overall uncertainty in the efficiency evaluated by the method can be broken down into four components The first 1s the uncertainty in the measured results of a standard point source The uncertainty originating from the sum coincident effect 1s included in this component The second lays in the self absorption correction factors With the code besides the statistical uncertainties in the Monte Carlo results users can set values to cover the uncertainties to take account of discrepancies between the used chemical compositions and the true ones The third one is in the positioning accuracy when a standard point source is set at the representative point for the calibration This factor has relatively small contribution compared with the other two For example the value of r z for any point 2 mm from the representative point is typically 2 3 or less whereas that at the representative point is 0 5 2 The last uncertainty is in the modeling of the detector in particular the treatment of ambiguous information inside the detector However both the position of the representative point and the self absorption correction factor are not significantly influenced by such indistinct and unclear information as the condition of
77. und a detector in a two dimensional R Z space which includes a detector axis E Definition of a lattice points and a point source nhE3 csv 0 500 7 000 o Diameter ar a saure Diameter or a Holder Thickness of a noder Lomposition of a holder Diameter of a hollow of noder Depth of a hollow of holder 1 R coordinate Z coordinate cm Users should set R and Z ranges in which the virtual point source is placed Note that the value in the left textbox 1s smaller than that in the right 2 Number of partitions for R Number of partitions for Z Assign the number of partitions division numbers for each range set in either the R coordinate or Z coordinate columns When the number of partitions is assigned as n the number of lattice points becomes n 1 Example In the case a range of 0 0 to 4 0 is divided by the number of partitions 2 then three lattice points are set at 0 0 2 0 and 4 0 3 Additional coordinate point s for R Additional coordinate point s for Z Users can set coordinate point s in addition to the lattice points set in 1 and 2 More than one extra point can be set by entering a comma in between two values Example 3 4 4 5 5 6 The additional JAEA Data Code 2008 017 coordinate point is designed to supplement the lattice points which have fixed intervals This should specifically be used for the following purposes One purpose is to improve reliability
78. window for data origination 1Dsoil csv 1 Default First a default style of a sample should be selected By clicking the button on the right side of the blank line users can browse and select the necessary file Parameter values of the default sample are then modified to specify the intended sample The default style itself cannot be modified in the GUI window but it can be modified or newly added in a text file The description format of the text file is given in Appendix A 8 Originally the CREPT MCNP code has a cylindrical sample and the Marinelli shaped IE78 sample as default style samples The geometries of these samples are shown schematically in Figs 2 7 for the cylindrical sample and 2 8 for the Marinelli shaped sample along with their parameters and default parameter values in Tables 2 7 for the cylindrical sample and 2 8 for the Marinelli shaped sample JAEA Data Code 2008 017 5 4 3 2 7 6 1 Fig 2 7 Half sectional view of a default style cylindrical sample Table 2 7 Parameters data types and parameter values of the default cylindrical sample File name cylinder csv Parameter EN Distance from basal surface of sample container to top surface of 4 5 6 7 sample cm Floating point 5 5 Outer radius of sample container em Floating point 42 6 Material of sample container Character 7 M
79. without material container A file containing the efficiency curve data of a volume sample without material and without container should be selected By clicking the button on the right side of the blank line users can browse and select the necessary file 6 Uncertainty in point source setting mm This option is used to take in to account any uncertainty in the setting position of a standard point source at the representative point The uncertainty r should be given in millimetres The resultant uncertainty in the efficiency will be the maximum difference between the calculated efficiency at the original point and that at a point which has a distance r from the original point 7 Button Run Calculation starts by pressing the run button and it will finish instantly JAEA Data Code 2008 017 2 5 4 Calculation Results Menu 2 5 4 1 Calculation Results Efficiency curves group A Menu Users can plot the calculated efficiency curve in a graph on the screen Both the horizontal axis photon energy and vertical axis peak efficiency are in logarithmic scales Users cannot change ranges of these scales However if needed users can export the data to a Microsoft Excel spreadsheet HE Graph of efficiency curve B x Call EXCEL Close Select data for display File name efficiency curves group Al Ri directian E nlcm z direction F 2 000 crm Efficiency Efficiency curve at A 8 000 Z 2 000
80. x 81 29 282 5920 E mail ird support jaea go jp Japan Atomic Energy Agency 2008 JAEA Data Code 2008 017 CREPT MCNP 1 1 Calibration Code for the Representative Point Method with MCNP User Manual Version 1 1 0 Jun SAEGUSA Department of Radiation Protection Nuclear Science Research Institute Tokai Research and Development Center Japan Atomic Energy Agency Tokai mura Naka gun Ibaraki ken Received July 7 2008 The representative point method is a novel method which enables efficiency calibrations using a standard point source A calculation code for use in implementation of the method has been developed The code is named CREPT MCNP Calibration Code for the Representative Point Method with MCNP The code estimates the position of a representative point which is intrinsic to each volume sample shape and also provides self absorption factors that correct the efficiencies measured at the representative point with a standard point source It can deal with photons between 20 keV and 2 MeV with p or n type germanium semiconductor detectors CREPT MCNP runs in the Windows PC environment as a GUI based application This manual describes the features of the CREPT MCNP code Keywords CREPT MCNP Efficiency Calibration Representative Point Method Standard Source Traceability Radioactivity Measurement Gamma ray Self absorption Efficiency Curve JAEA Data Code 2008 017 CREPT MCNP 1 1
81. y calibrations through use of this code JAEA Data Code 2008 017 2 CREPT MCNP Code User Manual 2 System Requirements The CREPT MCNP code is packaged software for readily implementing efficiency calibrations It was developed using Microsoft Visual Basic NET Lahey Fortran 95 and SPREAD for NET Windows Forms Edition version 1 0 9 0 The code works under Microsoft Windows operating systems version 2000 or XP and allows users easy and interactive operation with a GUI The recommended amount of PC RAM memory is at least 256 megabytes Either MCNP code version 4 Br00 or 5 XM05 and their associated cross section library data are necessary and should be located in a selected directory within the system When version 5 MCNP is used the X windows system need to be run in order to make the geometric models draw on the display The X windows system can be freely established on Windows PCs using the Cygwin tool CY 08 which is available via the internet The geometry plotting itself is done with a built in function originally included in MCNP as the ip protocol 2 2 Installation CREPT MCNP can be installed according to the following steps 1 to 5 1 Double click the Setup msi icon on the installation CD If NET Framework has not been installed on the PC the following message appears In the case users should install it by clicking Yes which then directs users to the Microsoft NET Framework website If installation was succ

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