On the Butterfly X-Ray Reflectometer
Contents
1. slitset3 tas medium angle sel hsl 1 mcslw 3 sel vsl 1 mcslw 12 sel hsl 2 mcslw 7 sel hsl 3 mcslw 8 slitset3 slitsetlb 2 98864 iv 1 ss 115 se 225 bs 10 be 110 slitset5 tas slit combination sel hsl 1 mcslw 5 sel vsl 1 mcslw 12 sel hsl 2 mcslw 12 sel hsl 3 mcslw 14 iv 23 30606 iv 39 89384 bs 20 be 110 ss 120 se 220 ss se bs be Use the function rdbf1y to read reflectivity data of this type of scan Assuming the current data path is home tascom data cmu2009 mark the prefix fina is called mark and the scan starts with the segn 123 the data are being read with following command cur path home tascom data cmu2009 mark dat rdbfly segn 123 fin segn 1 fina mark path cur path Assuming the overlap factors have been determined somewhere else f x in gnu plot and stored in in the array mm the reflectivity data are plotted is plotted with the command mm c 3000 000 30 000 12 000 2 500 2 000 1 475 plrty dat facs calc facs mm obviously the overlap factors can be adjusted in a straight forward manner by changing values in mm The next step is to discriminate the signal channel form the background ones At low momentum transfers q or at small angles of incidence amp for that matter the signal to noise ratio is so high that we may neglegt the background Since the vertical aperture is not changed during the reflectivity measurement we can use2. 1 BUTTERFLY OVERVIEW in the electronic rack like the ECB unit the motor drivers the high voltage for the PSD the detector electronics the histogramming memory the GPIB interface and the control computer are all powered up and running and you are logged into the tascom account To start the control program TASCOM you have to type tascomin the command line of an open terminal The program starts up and if everything is right you should view activity of the LED s of the GPIB ethernet interface indicating that TASCOM is trying to connect with the ECB module and the histogramming memory unit After TASCOM v3 15 DATA FILE DIRECTORY home tascom data cmu2009 benb TAS COMMAND FILE DIRECTOTRIES home tascom command emu jemu main SYSTEM COMMAND FILE DIRECTORY home tasfiles command sys SUPPORT FOR ECB SYSTEM with 36 motors TEMPERATURE CONTROLLER Mi YSTEM PREMA VOLTMETER ODA On line Data Acquisition ASCII Symbol table name cmu_sym sor ast loaded set up files x Gearing file Display file 9 04 2009 19 00 16 WX Y Y V He X HK HORE DESO RHEE C IO E OH ORG IO C oe on en m help function by typing HELP lt return OCHO ORE Figure 1 1 TASCOM screen after start up start up it will display it s version number the current data file and the command file directories plus a list of supported sub systems It should claim support for the ECB and MCA sub syste
3. 1 search for the characteristic line fx after sealed vacuum tube exchange 2 orient the beam along the flight tube axis 3 optimize the focused beam shape Warning work for G bel mirror alignment must be done with X ray tube powered on and shutter open Follow radiation safety rules 4 Use the portable counter before any new operation You must wear your radiation batches especially the finger ring Use lead shielding against back scattered radiation The safest place is to behind the tube Stand only on side with mounting plate for the mirror and tube case Always close the shutter before you change a slit lif you don t find any good marks or scratches or whatever go and take a ruler and scale and make your own ones 2 laser can be levelled with the help of a tranparent hoase Fill a 5m hoase with water and observe the menisca of both ends 2 2 ADJUSTMENT OF THE G BEL MIRROR 13 2 2 1 Adjustment of the G bel mirror from scratch Figure 2 2 The G bel mirror and its skrews Never touch the unlabeled ones slit 1 illumination slit insert slit 2 exit aperture insert moves the of G bel mirror case against beam focal height moves illumination slit slit 1 against G bel mirror moves exit slit slit 2 against G bel mirror tilts G bel mirror against beam tilts G bel mirror against slits combination of movement d and e of the G bel mirror better not move at all gp Th
4. er ober e eae rue AM FW ii CONTENTS 5 Technical Notes 37 SJ ceu ho SS Run ee 37 5 2 Siemes Kristalloflex 760 X Ray 37 5 4 1 Safety Circuit s eos bw seno due RAS 38 2 3 Hasknis Chiller mbi eee ERES 38 5 4 Sealed X Ray Vacuum Tube 40 3 3 BrauncPSD 2 4 54e RENS S Ba Bee OAM E 40 3 0 TASCOM 4 22 uat hex aed een fd 41 5 6 1 Adaptations of TASCOM for the CMU installation 41 25 6 2 Online zu ar ein ne Bea s Gn Bon nur 41 References 4 60 4 amp ble ee tree ie 42 Chapter 1 Butterfly overview Welcome to the manual for the Butterfly X ray reflectometer in the Supramolecular Structures Lab L sche group in the physics department at the Carnegie Mellon University You will find both annotations to other existing manuals and some detailed guidelines to the operation and maintenace of the spectrometer The reflectometer was custom designed for the then L sche group at the University of Leipzig by Jens Linder holm the founder of JJ X ray a commercial offspring of RIS the national laboratory of Denmark The spectrometer is controled by the ECB module in the electronics rack which is equipped with its own microprocessing unit motor controllers timers amp counters for the detectors and an basic video interface for the control displays The user can either
5. MBraun Mbraun 50mm PSD Manual now HECUS 2 Siemens KRISTALLOFLEX 760 X ray Generator 1993 1995 3 Per Skaarup TASCOM User Manual Ris 2003 4 Markus Weygand and John Zoll Siemens Kristalloflex 760 Butterfly Reflectomter logbook CMU 2008 23 24 Chapter 3 Macros 3 1 TASCOM go_home bfly alfa sbfly abeg aend npoi pres i0 soff of fa of f b npoi pres offbfly off husk_bfly atru direct alfa xwing alfa dwing alfa bfly pri alfa direct prialfa lisa sel hsl num sel_vsl num Les slpo mcslp p mcslp w rcsk pos width sabs abn abst lpsd CHAPTER 3 MACROS set the butterfly in a safe starting position move butterfly to specular reflectivity position of angle of incidence al fa basic reflectivity scan offset angle scan for current specular reflectivity position Typically 0 85 Qeritical apply an angular offset to current butterfly alfa state remembers danish at huske the current butterfly state as the state for specular reflectivity of an angle of incidence atru This is achieved by determing offset values which are added to the theoretical positions for motor move ments elevator towers translations and rotations of the flight tubes The command freezes the current state as the reference for the angle atru set the butterfly to direct beam of angle al fa set only the X ray source arm to the butterfly angle al fa set only the detector arm to the butterfly a
6. interact with the ECB control unit by operating the manual box or with the TASCOM control software package 3 on the Linux control work station via the GPIB interface The latter option is usually the choice in standart user operation The GPIB interface of the butterfly reflectometer is the ethernet version from National Instruments and hooked up to the control computer to a dedicated network card 1 4 Starting up Before you are beeing allowed to operate the X ray reflectometer you must have been gone through the online radiation safety instructions beeing personally instructed on how to control the machine and having been approved by the radition safety officer Alignment of the butterfly X ray reflectometer must be performed only by persons aware of and how to properly protect themselves and others against radiation haz ards You are required to sign into the X ray safety safety booklet 4 for the butterfly reflectometer whenever you fire up the X ray generator for a new experimental session and also write down the operation time In the following section we assume that the cooling circuit is up and running the detector gaz for the PSD is flowing the devices eased from the University of Leipzig and transferred overseas to Pittsburgh Carnegie Mellon University like the TASCOM command language or the Siemens Kristalloflex 760 X ray generator manuals 3http www cmu edu ehs radiological training html X raySafetyTraining 2
7. command sequences or execute macros which are inside the command directory The local command directory of the tascom account holds the macros to operate the butterfly spectrometer inside the 7 folder 1 2 TASCOM Round Trip The control software of the butterfly reflectometer is the C version of the program TAS that evolved from the original Fortran version developed at the danish national laboratory RIS in its glorious days In the following a big picture view is outlined in the hope to enable the user to grasp quickly the more detailed information from the TASCOM user and extension manuals 2 3 and even from its source code if needed The TASCOM program operations are centered internally around the values or states of the so called symbol table that holds the user variable names build in com mand names timer and counter names stepper motor names their parameters settings and their current position values The source code and binary of TASCOM is located in the folder in the home directory of the tascomp account on the Linux work station Under normal user operation TASCOM updates its values in the home tascomp cmu tas symfil symfil bin in an unfortunately binary representation An ASCII representation of the sym bol table exists but it is beeing used only in the rare case of a symbol table initialization where TASCOM reads the ASCII symbol table and then creates a new binary symbol table
8. structure write table ref H20 ref row names FALSE quote FALSI type help locator for build in help 32 3 Chapter 4 The Langmuir Trough 4 1 Hardware The Langmuir Blodgett Trough consists of an aluminium enclosure with a window capton foil for the X rays and carries a teflon trough inside Figure 4 1 Film balance mounted on sample table The small insert schows the alu minium support rails and the plexi glass pieces that support the trough The trough is fixed by four screws from below The temperature in the trough can be controlled using water flowing through copper tubings beneath the trough The trough mechanics comprises an electrical motor with a gear box which drives a teflon barrier via a belt The author of this manual has precision 33 34 4 THE LANGMUIR TROUGH machined a barrier made of Delrin Sensors can be accessed from outside the casing via air tight plugs such as the barrier position read out a potentiometer a Pt100 temperature sensor oxygen sensor and the Wilhelmi sensor for surface tension measurements 4 2 Tiger The hardware is controlled by a Film Balance Controller designed by Bernd Kohlstrunk at the University of Leipzig The controller can command the film balance stand alone For data read out however some external computer must communicate with that con troller via the serial interface The film balance controll
9. table gys goniometer y axis sample table Most of the motors are addressed in normal user operation indirectly by commands through the execution of specific macros Motors names not mentioned in this list are the ones for the slits and absorbers Those macros or cammands will be mentioned later and the inspection of their source is encouraged 1 2 2 Important system variables In the original symbol table source variables intended for a specific use are defined such as segn for the segment number suffix or fina for the prefix in the data file names Some system variables are state variables e g prsc which sets the scaler mode to either counting till a certain number to be defined in another system variable pres of counts or time others are read only variables like timers and scalers e g I A list of some of the more important system variables include I holds intensity value read by coun command TI holds value of timer started by a coun command RATE set to 1 enables rate meter set to 0 disables rate meter i e con tinous counting PRSC set scaler mode If set to 0 scaler is in time mode otherwise i 1 2 3 selects number of counts from detector i The butterfly uses currently only one detector the Braun PSD which is 1 2 PRES holds the preset value for the scaler SEGN holds current segment number DFIT holds comment string for the current data file CEMA center of mass calculated by built in stati
10. L An introduction is available in the documentation at the home page of the R Project http www r project org or closer to you at http lib stat cmu edu R CRAN refer ence card is located at http cran r project org doc contrib Short refcard pdf Type R in free terminal to start The command source parratt R reads the file parratt R into R This command is used for running batch files or loading macros 3 4 1 Reflectivity Calculation The Parratt iteration is implemented in the parratt function function x d del sig 2 7 bet 0 theta lt 0 5 abs x nmax lt length nx lt length x rn lt an lt f lt 0 c nmax nx if length sig 1 sig lt rep sig nmax if length bet 1 bet lt rep bet nmax 3 4 27 for i in 1 nmax fli sqrt theta 2 2xdel i 2ixbet i an 1 nmax 1 lt f 1 nmax 1 2 nmax 1 nmax 1 f 2 nmax 4 modified reflection coefficient if length sig length d msig lt array sig 2 nmax 2 c nmax 1 nx an 1 nmax 1 lt an 1 nmax 1 exp 2 msig f 2 nmax f 1 nmax 1 for n in nmax 2 rn n 1 lt exp 2 d n 1 lixf n 1 rnin an n 1 rn n an n 1 1 Re rn 1 Conj rn 1 fr lt Re rn 1 Conj rn 1 tr As an example of its usage a Fresnel curve for neutrons is being calculated The function qc2nrho calcul
11. MU is v3 15 and is identical to the TASCOM version used at the liquid surface diffractomter with some modifications The ECB module ancillary electronics and the motor drivers hardware is described in the docu mentation from JJX ray 1 5 6 1 Adaptations of TASCOM for the CMU installation e Moved home directory from usr users tascomto home tascom sim ilarly moved the accounts home tascomp and home tasfiles Some header files of the TASCOM source have been changed e The mca c file is being patched to work with the local MCA e Gpib driver updated to stable National Instrument version hooked up to a dedi cated network card e Makefile modified for updated gpib driver The symbol table is newly defined for the butterfly at CMU 5 6 2 Online The online program is an online visualization for current scan that belongs to the TAS COM 5 distribution A particular important feature is its ability to display the current mca histogramming memory content through shared memory communication with TASCOM Start the program pgplot for monitoring the current histogramming memory MCA content from a free terminal window cd home tascom tasplot Dec03 plot 3 0 0 30 You can monitor the MCA readings continously with the TASCOM command se quence 42 CHAPTER 5 TECHNICAL NOTES gt whle 1 eq 1 cmca wait 1 rmca next This sequence is for convenience stored in the macro 1psd in the command directory References 1 Jens Li
12. On the Butterfly X Ray Reflectometer Markus Weygand July 2 2009 Contents 1 Butterfly overview EI Starting up o edu er REIR RI Ub ee e veg 12 TASCOMRoundTrip lee 12 4 Importantmotors leen 1 2 2 Important system 1 230 Scans woe cR Rus ee bE ORO Se en E sl 12 4 MacOS cette cee e Ee Ba hare S ES 1 3 Operation 2 va x Bh Qo xdi ep mei 13 Absorber mM 1 3 2 Beg Rees References zs x e RE EIE Sea tye s 2 Alignment 2 1 Coarse lisnment us Lx LE be pet 2 2 Adjustment of G bel mirror 2 2 1 Adjustment of the G bel mirror from scratch 2 22 Shift and tilt the collimated beam 2 3 Alignment ofthe Butterfly hus do BSR ASS SE ae tat dosi ale eth oe d tete 3 Macros 3 1 TASCOM uos 332 On plot ss ze 2e aaa 3 3 Perl iv uS em CEN PESE Ew ee ae S 34 TR en Rt ces habs edo erp dnte tale WT V 3 4 1 Reflectivity Calculation 3 4 2 Read Data Files intoR 3 4 3 Tweak Reflectivity Data 4 The Langmuir Trough AAV s Ward wate to eda Bee bes 2 Teeba a e oiseau b s 42 1 I1S0WISQ 4 eco x eeu eh ee a References u
13. Trough and prepare a bare water surface Place the glass block in the range of the foot print and fill the trough with water so that the are cobered by a 300m water layer above Find the angular offset of the beam regarding the water surface The optical horizontal is a straight line by construction which may or may not be perfectly horizontally oriented Figure 2 9 Offset scan Remember that horizontal state for TASCOM with the command husk_bfly 0 Then make a sample height scan the arms still horizontal and position 22 2 ALIGNMENT tzs where the sample cuts half of the beam Then set the butterfly into specular reflective position and scan the sample height again and set t zs to the mid p gt bfly 0 85 gt tzs sma tzs tzs 0 3 tzs 3 31 1 tzs midp Then scan the angular offset and place the offset to the mid p gt gt offbfly midp You must probably repeat the sample height and offset scans and get iteratively to the desired state Once you have found a proper alignment remember this state for TASCOM as the reference state gt husk_bfly 0 85 Make a reflectivity scan of the bare water surface and check for the critical angle You can start as simple as gt slitsetlb gt attenb 8 gt sbfly 1 xac 2 5 xac 22 3000 1 Adapt old scan macros if necessary especially for slit settings and channel num ber for signal and background of the PSD References 1
14. and if that failes TASCOM issues an error message In case you assign a value to a variable that is not yet defined in the symbol table TASCOM adds a new variable to the binary symbol table Particularly it created a new symbol in the symbol table if you accidently misspell a variable name In order to avoid a symbol table pollution you should delete accidently user created symbols from the symbol table using the command dels e g dels tempp 3 X ray tube 2 PSD 3 Flight tube 4 Attenuator 5 Slit 1 6 852 Slit 3 13 sample table 14 Rotation arm source side rox 15 Rotation arm detector side rod 16 Height translation source arm t zx 17 Height translation detector arm t zd 18 Figure 1 2 Butterfly scheme 1 2 1 Important motors Translation sample height t zs Counter weight Translation x y sample txs tys Goniometer sample gxs gys Detektor holder G bel mirror This is the list of the most important motor of the butterfly reflectometer All the names have been defined such in the cmu_sym sor tzs translation z direction sample table tzx translation z direction tower X ray source side tzd translation z direction tower detector side 1 2 TASCOM ROUND TRIP 5 rox rotation X ray source side arm rod rotation detector side arm txs translation x direction sample table tys translation y direction sample table gxs goniometer x axis sample
15. ates the neutron scattering length density from a given critical angle qz seq 0 001 0 25 by 0 005 qc 0 021764 qc2nrho qc gt rsub slux lt 2 817938e 05 X rays slun lt 1 Neutrons slu slun the example is for neutrons parratt qz c 0 0 2x sluxpixc 0 rsub sig 2 7 gt refl plot qz refl log y 3 4 2 Read Data Files into R The following example illustrates how tasrd macro is being used to read some re flectivity data file ndata ref intoR rdng7 lt function file pgmD20_0507 ref path home tascom data read corrected Neutron data files 28 CHAPTER 3 MACROS parameter Qz R dR cur_file paste path file sep command paste tasrd R s parameter cur file print command data read table pipe command header TRU return data mypath home tascom myneudata myfile ndata ref data rdng7 file myfile path mypath print data structure information str data Note particularly the lines with the paste command that glues several strings together to one command string The convenience function num2fnum segn adds leading zeros to numbersand formates them in the same way TASCOM does the segn suffix in the dat file names This command the perl macro tasrd is then exectuted in the read table pipe command 3 4 3 Tweak Reflectivity Data A typical reflectivity scan on the butterfly is made of several scans with different slit and
16. attenuator settings Overlaps of subsequent scan serve to determine the overlap factor which comprises slit and attenuator settings and possibly sample artefacts husk ac ac ac ac h2o slitset05 attenb 7 sbfly O l ac 1 5 ac 31 3000 1 attenb 3 Sbfly 1 3 ac 3 ac 25 3000 1 attenb 0 sbfly 2 7 4 15 3000 1 slitsetlb sbfly 3 7 ac 5 5 ac 15 3000 1 slitset3 3 4 29 sbfly 4 5 ac 15 ac 10 3000 1 slitset5c sbfly 13 5 ac 28 ac 14 3000 1 sbfly 29 0 ac 5 1 3 3000 1 date attenb 8 slitsetlb ac husk ac The whole reflectivity scan comprises seven pieces and only the last two ones have the identical slit and attenuator settings The s1itsetXX macros contain setting for the slit 1 the footprint slit slit B footprint Figure 3 1 The slit width on the left defines the width of the incoming beam under angle The wider the beam is the larger the footprint f gets f w x sina The divergence of the beam is dominated by the G bel mirror divergence 0 05 slitset05 tas small angle sel hsl 1 mcslw 0 5 sel vsl 1 mcslw 12 sel hsl 2 mcslw 7 sel hsl 3 mcslw 8 ss 115 se 225 bs 10 be 110 1 2755 slitsetlb tas small angle sel hsl 1 mcslw 1 sel vsl 1 mcslw 12 sel hsl 2 mcslw 7 sel hsl 3 mcslw 8 ss 120 se 220 bs 10 be 110 ss 115 se 225 bs 10 be 110 30 CHAPTER 3 MACROS 1 2755
17. ce arm This step is ususally necessary only after a complete dismantling of the reflectomter rather seldom Figure 2 1 Butterfly no parts mounted on the flight tubes The first step is to place the arms of the naked figure 2 1 butterfly horizontal as good as possible using the rotational degrees of freedom i e motors rox rod Make the motor adjustments from the manual box Use first the scale of the goniomters there might be still some usefull marks from previous work Then take the telescope 11 12 2 ALIGNMENT and use appropriate marks at the front and back end of the arm you want to level After leveling the arms place them on the same height using the translational degree of freedom i e tzx tzd and the telescope When this is done the to flight tubes have to be aligned uniaxially This is done by adjusting the lower arm 2t 1 in the plane of incidence so that both arms are aligned uniaxially Use a horizontally levelled laser to perform this task Obey laser saftey rules When you found an optical horizontal remember husk this setting with the com mand husk hor Later you can move the motors back to that horizontal reference position with the command gohor Help on alignment is availible in the TASCOM help system just type help refl 2 2 Adjustment of the G bel mirror The adjustment of the G bel mirror falls into three stages
18. dently ctr dinstead of ctr c TASCOM still keeps running in the background and you can get the TASCOM console back to forground by typing g into the terminal window After a succesfull scan you can assign the sample height to the calculated midpoint value tzs midp The command directory of the butterfly reflectometer holds many more sophisticated scan macros for operating the spectrometer 1 2 4 Macros The typical structure of a macro is explained in detail in the TASCOM user manual Nevertheless a particularity of the use of semicolons in TASCOM is beeing outlined here Whenever TASCOM parses a macro it parses the source till a the occurance of a semicolon and then executes This can have interesting consequences f x if you decide to seperate operations in a macro by a semicolons and say the first piece till the semicolon parses without an error message then TASCOM will execute that part and parse the next piece of code till the next semicolon If a subsequent piece of code has an error an error message will be issued and causes TASCOM to abort the execution of the macro It is thus adviced to check the macro for errors before executing it for a scan especially if that one is intended to take a long time 1 3 Operation In the following the normal operation of the butterfly reflectometer is outlined We assume the butterfly reflectomter is aligned all sub systems are up and running and a liquid interface in the Langmuir Blodgett troug
19. e adjustment of the G bel mirror is done visually with the help of flourescence screens and the X ray eye and CCD camera The observation is done after the first flight tube in the sample table areal Remove all attenuator slides out of the beam type either atten lorattb 0 Insert the 6mm slit in the slit 1 holder remove the exit slit slit 2 figure 2 2 and cover the opening of slit 2 at the side with a partially inserted slit or a piece of led Unmount slit 1 from the butterfly scheme figure 1 2 not the G bel mirror if it is not yet unmounted and pose it on the floor or on the flat area of the 2tu arm 14 2 ALIGNMENT Operate the X ray tube under lowest power 20kV 5 mA and open the shutter 2 You must check for scattered radiation in the surroundings of the tube with the portable counter and apply lead sheets and lead plastic shield as needed Never stand at the side where the slits are being inserted in the G bel mirror case when the shutter is open the front side in figure 2 2 The mirror is essentially a plate that must be lowered and slightly tilted against the incoming X ray beam The correct tilt is required to get the desired monochromatic X ray beam First level the skrews d e and f so that they align flatly with the case You must always move the skrews first in downwards direction and then upwards to the desired position in order to compensate for the mechanic backlash You should be able to see a
20. er comes with its own docu mentation 1 2 4 2 1 Isowiso XF A program written by the author of this manual Markus Weygand can issue commands to and read data from the film balance controller It is made available in the local bin directory of the tascom account The communication is done with serial protocol over an USB to serial interface converter In order to read the current status i e position lateral surface pressure and area from the film balance controller type isowiso a isowiso 1 1 for a continous output every second Examples of isowiso usage are isowiso v a read current status i e position lateral surface pressure and area isowiso v l arg read current status every arg second isowiso v b read current barrier position isowiso v l arg read current status every arg second isowiso T switch sets output prope for TASCOM command the owl isowiso b arg set barrier position soll isowiso p arg set lateral surface pressure soll isowiso s arg set speed index 0 9 isowiso v g 1 f xxx ref store curent status to file xxx ref every second 1sowiso c a comment add this option to the above command to store a comment in the created data file Read the current status from inside TASCOM with the command owl isowiso T a pos pi lat area REFERENCES 35 which stores the result of to the TASCOM user variables pos pi_lat and area Type isowiso h for the build in help informati
21. file After such a procedure most likely information like current motor positions modified gear parameters soft limits user defined variables and so on are lost render ing the spectrometer in an ill defined state needing some work to be done to get all symbol table values restored and return the spectrometer operational at least from the software side point of view The ASCII source file being used in the CMU incarna tion of the butterfly reflectometer is located at home tasfiles symfil cmu sym sor on the tasfiles account For the sake of completness the motor parameters multi plexer and display files for the CMU butterfly installation are located in home tasfiles command cmu gea tas home tasfiles command cmu mux tas home tasfiles command cmu dis tas Note the obvious adaptations of those files names to the particular installation and mind to adapt your actions accordingly in case you want to follow procedures described in STASCOM is the shortcut for Triple Axis Spectrometer Communication program 1 BUTTERFLY OVERVIEW the TASCOM user manual 3 TASCOM features its own macro language which is somewhat fortranish in its syntax but does not require a strict format nor capital letters Macros can be defined and placed in the command directory in files with an extension tas in the file name On typing a command in the command line TASCOM searches first its symbol table and if that fails the command directory
22. gt M13 gt ab3 These values should be checked The macro patten prints the current absorber state 1 3 2 Typical scan A sample is prepared in the LB trough or a waver is mounted on a flat support in the center of the sample table The reflectomter is put in save starting state with the command go_home which cares for slit settings of slit1 attenuator settings and sets the reflectomter to 0 75 x critica so that the sample surface is expected to serve as a mirror The critical angle is stored in the user variable ac and it is up to the user to update its value to e g water or silicon oxide surfaces ac_h2o or ac si Figure 1 3 The flight tubes point to the sample placed in the center of the sample table A sample height scan is performed typically in the reflected position at butterfly setting of the angle at 0 85 8 1 BUTTERFLY OVERVIEW Open the shutter 1 on the front of the Siemens X ray generator 1 The reflectomter is in a position where the sample serves or should serve as a mirror and just the right height of the sample has to be determined This is usually done in a two step process In the first step select the motor t zs with the manual box and use the joy stick to move the motor and watch the rate meter or the counts second on the monitor from the ECB module Once you have found the maximum count rate you can start a scan attb 9 gt or whatever the necessary attenuation is
23. gt bfly 0 85 gt tzs sma tzs tzs 0 3 tzs 3 31 1 If the scan is done and the result looks like a gaussian with fwhm of 0 25 you can set the sample height to the maximum tzs midp In case you want to check alignment or make a scan of a waver you need to perform an angular offset scan which will be explained in more detail in the alignment section gt Soff 3 5 3 3T 1 If a proper maximum is found set the new angular offset value gt of fbfly midp in order to set the reflectometer to the maximum position If the offset is off repeat the sample height and offset scans until you find iteratively a stable configuartion The command b 1y alpha sets the incident and exit angle to the alpha The command sbfly abeg aned npoi pres iO is the primitive scan macro for reflectiv ity scans Its usage for complete scans be looked up in macros like gold tas or mucus tas in the command file directory Slits The slits are motorized and slit settings can be modified during operation An exam ple provide the scan macros mucus which calls macros like slitset1b to set the horizontal opening of slit 1 The settings of slit2 and slit3 remain unchanged as set in the initial instrument alignment The horizontal slit width opening of slit 1 is particularly crucial during an reflectivity experiment For shallow angles of incidence the horizontal width of slit 1 must be set small to reduce footprint size of the incoming beam whe
24. h of proper height is the sample A liquid surface has the advantage that it is horizontal by gravity whereas a solid sample 1 3 OPERATION 7 might need first an alignment to be horizontally to the beam using the goniometer motors which is an obvious step preceding the following procedure 1 3 1 Absorber The detector should not get much more than 6000 counts second Thus the direct beam must be attenuated in order to protect the detector PSD which is done by the attenuator The attenuator is modified slit where the motors moves instead of jaws aluminium foils of different thickness into the direct beam The four jars carry 2 4 8 or 16 layers of an aluminium foil thus totally 16 absorber settings are possible Make sure that you select an appropriate absorber settings once you put the reflectometer into a direct beam or low angle setting attb number sets attenuator factor by selecting a state between and 15 State 15 has all absorber slides in beam and the highest attenuation state O all attenuation foils out of the beam atten val set attenuator value to an attenuation factor of at least val For info from online help type help atten The macro atten defines internally attenuation factors for each of the alumium absorbers which go into the calculation od the attenuation factor atte atten 50 2 4 I gt M21 gt abO atten_sl 4 8 lt gt M14 gt abl atten s2 27 2 I lt gt M29 gt ab2 atten_s3 777 8 I
25. il doug haskris com If you change the X ray tube you must switch off the chiller and unhook the hoases from the tube stand Remember which tube was pumping the water in and which one out The direction matters 5 4 Sealed X Ray Vacuum Tube The X ray source is a fine line copper sealed vacuum source The operation power settings are 45kV 35mA Increase first the high voltage to target value and then current 5 5 Braun PSD Figure 5 3 The detector gaz bottle The fitting is customized in order to connect to the MBraun gaz hoases The detector is described in the producers manual 2 The fitting for the detec tor gaz has been customized figure 5 3 Select the PSD as the current detecor from TASCOM with the following counter setting 5 prsc 2 You must set rate to 0 during a scan and to 1 to be able to read the current counte rate on the b w display of the ECB module The TASOM user manual 5 describes the MCA commands for reading clearing the histogramming memory and the timer functions that are availible to TASCOM through the ECB module 5 6 TASCOM 41 MBraun no more sells position sensitive detectors and this business is taken over by the austrian X ray systems GmbH HECUS Reininghausstrasse 13a A 8020 Graz AUSTRIA Tel 43 0 316 481118 Fax 43 0 316 48 1118 20 e mail officehecus at Office Hours Mon Thu 08 00 16 00h Fri 08 00 12 00h CET 5 6 TASCOM The TASCOM 4 5 version used in C
26. m The collimated beam must be oriented uniaxially to the flight tubes A small deviation however can be dealt with easily in the subsequent alignment Changes in the tilt of the collimated beam must be done by altering the initial height of the G bel mirror casing skrew a Then proceed with the same procedure as described in the last section When the colliminated beam is oriented well enough uniaxially respectively to the flight tube insert the 0 6mm slit in the exit aperture slit 2 in figure 2 2 of the G bel mirror case and adjust its height using skrew c until the beam is visible again figure 2 4 iv Figure 2 4 The detector holder can be used for holding the X ray eye with an cylidri catal adapter or the PSD right after the first flight tube during G bel mirror optimaza tion and subsequent alignment For the final optimazation of the collimated beam power the X ray generator up the operating power of 45kV 35mA and wait least 90 min to reach termal stabilty 16 2 ALIGNMENT Observe the collimated beam with the X ray eye and maximize the intensity of line by adjusting slightly the height of the illumination slit the G bel mirror height and tilt using the skrews b a and d Optimize the beam by adjusting slightly the exit slit height and the tilt of the mirror against the slits using the skrews d and c If you don t trust your eyes and want quantitative information perform the last step with the PSD and ob
27. m as those are essential for operating the spectrometer Don t worry about missing support messages for the temperature controller and PREMA voltmeter these are devices being present at a particular synchrotron beamline in the HASYLAB DESY Hamburg and reveal the history of the control software as an adapted version of the one that controls or used to control the horizontal liquid surface diffractometer at BW1 It is worth mentioning that TASCOM provides the command ow1 that allows the user to easily communicate to external programs which could virtually control anything and communicate back to TASCOM without the need of a specific internal control software add on or modification The ODA on line Data Acquisition supports an external plotting software package which comes particularly handy for monitoring the current histogramming memory read out of the PSD detector signal Then it will print the symbol table multiplexer file gearing and display file After the transfer overseas from Leipzig to Pittsburgh the author of this manual upgraded the control software TASCOM to the most recent version Some adaptions for CMU are listed in a dedicated section in this manual Soriginally implemented by the author of this manual 1 2 TASCOM ROUND TRIP 3 names and locations which are so important to the system that they deserve beeing mentioned 3 Finally it will print the TASCOM command line prompt gt You can type in TASCOM
28. nderholm Losche Leipzig S2641a JJ X Ray 1996 2 MBraun Mbraun 50mm PSD Manual now HECUS 3 Siemens KRISTALLOFLEX 760 X ray Generator 1993 1995 4 Per Skaarup TASCOM Extension Manual Ris 1997 5 Per Skaarup TASCOM User Manual Ris 2003 6 Markus Weygand and John Zoll Siemens Kristalloflex 760 Butterfly Reflectomter logbook CMU 2008
29. ngle al fa like bf1y but only prints hypothetical movements No movements made like direct but only prints hypothetical movements No movements made list current butterfly state select horizontal slit num num 1 2 3 as the current one select vertical slit num num 1 2 as the current one list curren slit positions list all slit positions move current slit position to p move current slit width to w remo current slit setting to pos and width moves absorber blade abn in if abst 1 or out if abst 0 read contiously the MCA histogramming memory This macro is useful for observing the current PSD counts 3 2 GNUPLOT 25 3 2 Gnuplot Macros can be loaded in gnuplot by the command load macro A useful macro is rsn which has Fresnel functions for the reciprocal and angular space defined set log y qc h2020 0217 qc si 0 0314 qc qc h2o ff x x x qc qc x 5 f x x lt qc 1 x ff x x ff x 2 fs x s f x x exp x x sx s a2q x 4xpi 1 542xsin 180 fa x f a2q x fsa x s fs a2q x s The macro reload repeats the last plot commando which comes handy during scans Printer output can be placed conviently into a macro such as print Adapt it to the latest printer names and or the desired Postscript or other terminal options options set ter post color set output lpr Pbutterfly set ter post color set output lpr Phpcolor set ter post mono set output l
30. nly horizontal jaws gt sel_hsl 3 gt mcsiw 15 Close the vertical jaws slit 1 slightly in order to allow to discriminate background and signal channels on the PSD The commands needed could be something like gt sel vsl 1 mcslw 12 A sample slit scan is performed like gt Scslp 25 25 31 1 Remember that you can move the here vertical position with the slit moving macro mcslp p if you need that In order to track en3 follow the direct beam with the PSD mounted at the back of the second flight tube under various angles of incidence starting by remem bering the optical horizontal reference position direct O0 gt rememeber the reference TZD position sdhe tzd to set the instrumet to O tilt Set the butterfly to various tilts of the dirct beam like 0 0 5 1 1 5 2 2 5 3 2 3 ALIGNMENT OF THE BUTTERFLY 21 Figure 2 8 The butterly set to the direct beam gt direct 0 5 Scan the height of the second flight tube note the found midp and its difference to the theoretical value sdhe which was calculated by the direct macro A convenience macro exists in the command directory that prints that difference gt diffd Write down the angles and the differences on paper and or to a file and calculate the linear regression f x with gnuplot In case you spot a systematic devia tion correct the value of en3 accordingly and check if the correction was done properly Mount Langmuir Blodget
31. nts Note its position value into the TASOM variable t z sb Track the length en1 The command bf1y alpha moves the butterfly into the expected position for specular reflectivity under the angle of incidence alpha The proper operation depends on correct values for the lengths en1 en3 in TASCOM The read the current values in TASCOM type gt lenl len3 Assign your newly measured length values to TASCOM variables en1 and len2 and make TASCOM remember the current position of the X ray side of the butterfly as its reference horizontal position for reflectometry calculations gt husk xwing 0 2 3 ALIGNMENT OF THE BUTTERFLY 19 Figure 2 7 Track length en1 with the cross and X ray eye If lenl was perfectly correct the direct beam would always hit the center of the cross and being obscured from the X ray eye check tzs with manual box if the incoming arm is being set to the calculated position for any chosen incoming angle a pha The macro which moves only the motors for the first arm into the calculated butterfly position under an angle alpha is called xwing and used like xwing 2 in order to position the first arm to the theoretical position for the angle of inci dence of 2 The tracking of the error is done by observing the deviation of the center of the cross from the beam under various angles like 0 0 5 1 1 5 2 2 5 3 3 5 4 4 5 degrees Obviously the height of the X ray eye must be adjusted for la
32. on References 1 Bernd Kohlstrunk Manual Balance Controller Version 2 0 University of Leipzig 2 Bernd Kohlstrunk Menu scheme Balance Controller University of Leipzig 36 4 THE LANGMUIR TROUGH Chapter 5 Technical Notes Finally a collection of facts and pieces of useful information on the equipment are given 5 1 JJXray This company did design and construct the spectrometer They are located in Danmark Their web page is http www jjxray dk conus html JJ X ray A S Diplomvej 377 Scion DTU DK 2800 Kgs Lyngby Danmark Telephone 4 454776 3000 Fax 45 4776 3001 VAT DK 2952 3215 5 2 Siemes Kristalloflex 760 X Ray Generator The Kristalloflex is the high voltage source for the sealed X ray vacuum tube This device is usually part of a Siemens X ray solution JJ Xray chose only the generator part for the butterfly design Siemens no longer owns the X ray department and sold it to Bruker Contact Bruker AXS for Inc for service needs It is helpful to tell that to a Bruker AXS service person 37 38 5 TECHNICAL NOTES USA and Canada BRUKER AXS Inc 5465 East Cheryl Parkway Madison WI 53711 5373 USA Tel 1 800 234 XRAY For customers calling from US or Canada 5 2 1 Safety Circuit The safety circuits 3 of the X ray generator include the door interlook which is a mgnetic switch at the door to the X ray experimental enclosure If this circuit i
33. pen it 500 um wide gt sel_hsl 1 gt mcslw 5 The next step is to perform a height scan of the slit aperture The macro scs1p performs a scan relative to the current position and returns to the position before the scan e g 18 2 ALIGNMENT gt scslp 30 30 31 1 Mind that these scans should be used with some care so that you don t exceed the mechanical limits in the planned jaw movements Reduce the scan range from 30 as in the example above to say 10 for the fine scan Move the slit position to the center of the scan mcslp midp After the slit height is found check for the slit width and scan the slit width using the current slit width scan gt scslw 70 10 81 1 Like in the position scan this macro returns to the slit state before the scan You can assign a slit state a position value p or and the slit width w The com mand macro uses internally the remo command 3 You are responsible for a meaningful result gt rcslp p w And finally you can print the current slit settings values lcsl For the sake of completness the macro s1po prints info about all slits Mount the X ray eye instead of the PSD in the detector holder using the custom machined cylindrical aluminium adapter observe the direct beam with the X ray eye Place the cross in the sample table center and move the sample height table tzs so that the cross just obscures the direct beam use the Manual box slow moveme
34. pr Posage repl set output plot ps repl set ter X11 repl Rich documentation for gnuplot is available inside the program through the built in help system and the gnuplot home page http www gnuplot info 3 3 Perl The macro extracts information from TASCOM data and array files Extract for example the data columns for Q1 REFL SREFL from a reflectivity data file xxxx007 ref with tasrd s O1 REFL SREFL xxxx007 dat Values stored in the paramter line are being extracted with the additional option switch p e g p s ss se bs be xxxx007 ref Arrays are accessed by indicating square brackets or by an index range 26 CHAPTER 3 MACROS tasrd s Ql DD xxxx007 dat tasrd s Ql DD 23 90 xxxx007 dat The sum over an array range is taken with prefix s inside the square bracket after the array name e g tasrd s Ql DD s23 90 DD s100 200 xxxx007 dat Values stored in the paramter line are extracted just with the additional option switch e g p s ss se bs be xxxx007 ref A mixed access to file parameter and header parameter is possible as well in that order with the option P e g tasrd s Ol REFL SREFL P s ss se xxxx007 ref Type tasrd h for the build in help 34 R R is a software environment for statistics with rich graphical capabilities and features a functional programming language In some ways it is similar to Matlab or ID
35. reas for larger angles of incidence the footprint of the incoming X ray beam has a reduced and it is desirable to make the horizontal width of slit 1 as wide as pos sible to get as many photons hitting the sample Slit 1 and have horizonatl and vertical openings whereas slit 3 has only a horizontal opening REFERENCES 9 Slit commands Slit commandos operate on the current slit The current slit is selected by the com mands sel_hs1 123 for a horizontal slit or sel vs1 12 for vertical apertures The slit help page provides additional information of the slit settings macros sel hsl 123 select horizontal slit to current slit sel vsl 12 select vertical slit to current slit slpo list all slit settings lest list current slit setting mcslp p move current slit to pos mcslww move current slit to width scslp pmin pmax npoi pres scan relative to current position scslw wbeg wend npoi pres scan slit width of current slit rcslp p w rename current slit state to position and width References 1 Siemens KRISTALLOFLEX 760 X ray Generator 1993 1995 2 Per Skaarup TASCOM Extension Manual Ris 1997 3 Per Skaarup TASCOM User Manual Ris 2003 4 Markus Weygand and John Zoll Siemens Kristalloflex 760 Butterfly Reflectomter logbook CMU 2008 10 1 BUTTERFLY OVERVIEW Chapter 2 Alienment 2 1 Coarse alignment The coarse alignment is the optical adjustment of the detector and sour
36. rger angles of incidence The theoretical relative height displacement of the flight tube respective to the horizontal position for an angle of incidence amp is txhe len x tan Note down the observed deviation Az tzs tzsb where tzs is the position of the sample height where the cross precisely obscures the X ray beam The macro diffs prints this difference for convenience that is the rea son you stored the sample height for the horizontal case Make a file with the values 0 for the angles of incidence and the observed deviations Az You can use gnuplot to fit the linear regression curve type help fit inside gnuplot Fix the value of lenl if a systematic deviation could be traced 20 2 ALIGNMENT Unmount detector and align the detector arm to the plane of incidence with the help of a flourescent screen and adjust the 2t1 either using the manual box or manually with unhinged motor gears Mount slit2 and slit3 open jaws wide Mount detector holder towards the end of the second flight tube Align slit2 The procedure is similar to alignment of s it1 Start with selecting the 5 2 gt sel_hsl 1 gt mcslw 10 The scanning commands are now exactly the same Mind that because of the slight divergence of the collimated beam the slit must be set wider in order to catch the direct beam Scan the position and the scan the width Align slit3 The same procedure like for slitl and slit2 except that this slit has o
37. s open the shutter at the X ray tube holder closes or does not open One way interrupt the interlock is to pull off the bana plug at the bottom of the X ray tube stand 6 Outside the enclosure an X ray warning light is switch on via a relais if the X ray generator engages high voltage to the X ray tube If the shutter is open a warning light inside the experimantal enclosure is being engaged Failure to engage this warning light will result in a breakdown of the interlock If the light bulb is dead ity must be replaced Figure 5 1 Backside of the X ray generator Customized 9 pin and 13 pin plugs bridge safety circuit settings 3 The safety cables serve for the interlock the X ray warning lamp and the shutter warning light bulb 5 3 Haskris Chiller the Haskris chiller is a refurbished model bought from JS Technical Services Their address is Marguerite Stauver JS Technical Services 5 3 HASKRIS CHILLER 39 940 382 2934 Voice 940 898 0150 Fax 6159 Moss Rose Lane Aubrey TX 76227 www jstechnicalservices com e mail jstech1 airmail net However since it is a Haskris device you better deal with Haskris for spare parts such as the brass pump Figure 5 2 Haskris chiller The brass pump is a consumable Hi Marcus PN 1370 Pump Model 102L100F11XX 131 91 ea excluding freight Pump includes new coupling Doug Wagner Haskris Co tel 847 956 6420 x243 40 CHAPTER 5 TECHNICAL NOTES fax 847 956 6595 ema
38. s serve as a guidline and don t replace totally own thinking scan ranges needed may be different and so on it is also strongly recommended to look into the macros Mount the aluminium plate with the round recess in the center on sample table You might have to unmount another aluminium plate from the sample table tower most likely the ground plate for the Langmuir Blodgett trough Center a pin on the sample table take the small goniometer with the sharp pin which fits precisely in the round recess of the square aluminium support plate You the telescope as a visual aid and observe the tip under a 90 rotation of the sample table to do this unhinge the gear box of motor TS Perform these rotations manually and be gentle with the cables around Determine en1 and len2 with steel rulers as well as you can Mount the detector holder on the second flight tube so that it can carry the PSD in the sample table area Search the direct beam moving the height of the second flight tube t zd using the manual box Mount slit 1 and align slit 1 Set the attenuator and start with the hightest at Figure 2 6 Align slit with the PSD mounted in the sample tabe area tenuation factor attb 15 or atten 200000 The unit of the slit motors movements are set to multiples of 100 um Most likely the the slit settings from the previous alignment are somewhat useful especially the widths and position Select the horizontal aperture of slit and o
39. serve MCA read out with the online graphical visualazation program under an update rate of 1 second 1 3 You must attenuate the direct beam in order to prevent damage of the detector Start with the highest attenuation factor and lower it until the count rate is in the range of 6000 counts second 2 3 Alignment of the Butterfly The butterfly geometry is an essentially symmetric setup designed for specular reflec tometry on liquid or other planar surfaces oriented in the horizontal plane len 2 Figure 2 5 The lengths len and len3 must be known for reflectivity operation mode The xy movements of the sample table must be adjusted with the help of a telescope so that a pin placed in the recess is perfectly centered The centered sample table carries later a precision machined cross being used in th alignment The sample is mounted on the sample elevator table and rests there during the measurement Both the source side and the detector side arm possess a translational 2 3 ALIGNMENT OF THE BUTTERFLY 17 and a rotational degrees of freedom and even more degrees of freedom if we consider the possible slit movements Due to the pattern of the arm movements in an experiment people called this type of reflectometer a butterfly The initial optical alignmet of the flight tubes into a horizontal plane serves as the starting point for the fine alignment of the butterfly pp 11 The fine alignment breaks up into the following steps these step
40. simple bright band on the flourescent sreen above the center of the flight tube figure 2 4 1 Make sure that this band is not confined by the illumination slit and use the skrew b for adjustment Turn skrew a and move the band until an upper confinement appears Now tilt the G bel mirror by turning skrew d up to the point where the upper confinement remains unchanged figure 2 4 ii The mirror is positioned parallel to the beam 1 a ee a u Figure 2 3 The major steps in the G bel mirror alignment i with illumination slit 6mm a broad bright band is visible on the flourescent screen or the X ray eye ii tilt G bel mirror parallel to the X ray beam iii insert the 1 mm illumination slit and select the Cug line iv insert the 0 6 mm exit slit The next step is to tilt the mirror forward by turning skrew d inwards into the casing At some point Kg line will appear and then the Kg line The tilt skrews d e must optimized so that the line gets intense 3The Kg line is made of two lines Ko that are close together 2 2 ADJUSTMENT OF THE G BEL MIRROR 15 Now insert the 1 mm illumination slit and place the 6mm in the exit aperture holder Vary the height of the illumination slit skrew b until the bright line reappears and a small remaining of the bright band is visible figure 2 4 iii If only the band is visible then the illumination slit is too low 2 2 2 Shift and tilt the collimated bea
41. stic function in the plot command MIDP holds the mid point of internal statistics evaluation Very useful for scans You can print the value of a variable a motor position or perform a calculation using the print command f x the number of counts measured during the last coun command 7 symbol table entry has scope field a number that is used by TASCOM to discriminate the type of a command sting after parsing it variable command read only variable etc 6 1 BUTTERFLY OVERVIEW 1 2 3 Scans Scanning the motor position against detector counts is a frequent task during operation the butterfly The basic scan macro sma for scanning the absolute position against detector counts is provided in the tasfiles command directory Its usage is sma motor start pos end pos steps pres The following line is frequently used for the sample height scan before a reflectivity measurement tzs sma tzs tzs 0 3 tzs 3 31 1 The first command tzs prints the current motor position the second command sma tzs scans the motor tzs in 31 steps 40 3 against its current position t zs Note that the value of the sample height is plotted before the height scan This is a good pratice in case you decide to move the motor position back to the original value scans and macros can be stopped by hitting ct r c Mind that the sequence ctr d suspends on Unix Linux a program to the background If you happen to hit acci
42. the small angle region for the signal background discrimantion The plrty command displays per default the 2D image figure 3 2 of the reflec tivity scan where on the y axis the PSD channels are being displayed up to the applied overlap factors and on the x axis the momentum transfer q R provides the function 3 4 31 1 256 150 200 250 100 50 0 1 0 2 0 3 0 4 0 5 0 6 0 7 dat QZ sndx ix Figure 3 2 The 2D image of a reflectivity scan of a water surface in the Lang muir Trough displayed using the command plrty With the build in R command locator itis easy to determine the channels numbers in the image with the mouse locator that gives you coordinates of the image back you have clicked at Click with the left mouse button the on the borders of the signal range and do use many spots in the low angle region and determine the signal range ss se signal start signal end Determine the backgr ound range bs Don t use blindly a too low channel number for bs in order to avoid the detector edges Update the s1itsetXX macros to the new ranges The reflectivity data is being recalculated based on the novel ranges with the twrt y function twrty dat facs calc_facs mm bounds list ss 126 se 216 bs 15 be 125 gt ref Finally the data structure ref can be inspected with R command str An easy way to store the corrected reflectivity data is using the R command write table str ref 4 shows data
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