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TOSCA User Manual

1. 1 Gauges 2 4 To cryostat He in 3 Pump Figure 2 10 The pump manifold and sketch showing the numbering of the valves TOSCA User Guide 22 66 11 Close valve 2 when the vacuum gauge shows 1000 mbar Note Because the vacuum gauge on the cryostat pump will automatically release excess pressure VALVE 4 MUST BE CLOSED 12 Remove the thermometer connection by unscrewing the upper silver knurled nut Figure 2 11 DO NOT UNSCREW THE LOWER BRASS NUT 13 Unscrew the retaining bolts at the top of the sample centrestick and withdraw the centrestick smoothly but RAPIDLY Figure 2 12 Figure 2 11 The thermometer connection on the CCR TOSCA User Guide 23 66 Figure 2 12 Illustrating centrestick withdrawal TOSCA User Guide 24 66 Figure 2 13 Photo graph of the cryostat with the centrestick withdrawn and blanking flange in place The blue valve on the side of the CCR and the pressure gauge are labelled 14 Cover the cryostat top with the blanking plate and bolt it down Figure 2 13 If it will be more than a few minutes before the next sample is inserted the helium should be pumped out see 19 and 20 This keeps the cryostat cold and reduces cool down time for the next sample 15 Take the centrestick to the work bench and replace the old sample with new sample see Section 2 2 and 2 6 If a different centrestick is to be used ensure that the sample is inside the lead castle on the work bench 16 U
2. www isis rl ac uk GenieReferenceManual The advantage for TOSCA is that it enables a QREHACK to be carried out in less thana minute rather than the five minutes or so required by GENIE To start OPENGENIE create a DECTERM in window 3 and then type at the TOSCA prompt TOSCA gt OPENGENIE lt A series of initialisation messages are printed followed by a caveat emptor notice OPENGENIE is different from GENIE in that the number of workspaces is essentially unlimited and they can be called almost anything However for continuity with GENIE workspaces will be called w1 to w16 To look at the current run type qrehack_fb lt The S Q w data is placed in w5 forward scattering detectors and w7 backscattering detectors To display the file type d w5 50 100 0 1 0 3 lt A PGPLOT window is created and the data displayed in it as shown in Figure 4 1 Thus the display command is the same as in GENIE The p overlay command is also the same The default x axis of the display is meV to convert to cm type TOSCA User Guide 53 66 w con w5 lt where is any integer To change the binning type a b note difference from GENIE which is a b DECterm 57 fRepieted mins EOT oF A Displayed using bin grouping of 1 Displayed using bin grouping of 1 Displayed using bin grouping of 1 Displayed using bin grouping of 1 Displayed using bin grouping of 1 Displayed using bin grouping of 1 DIS
3. A procedure that will always work but is somewhat more long winded is to type k h This carries out a screen dump of the GENIE display window and creates a postscript file called DEC_POSTSCRIPT DAT in the directory you are currently in To print this file from GENIE j plaserx dec_postscript dat Where x is the number of the laser printer see table 4 1 Remember to change the disk directory name if your file is elsewhere These files are purged frequently so it is inadvisable to do too many at any one time 4 1 6 Using the cursor Should you wish to find the exact co ordinates of a peak for example you can type C A cross hair will appear in the GENIE graphics window This can be positioned using the mouse When in the correct place click the left button and a menu will appear select the desired option To exit from the cursor it is necessary to choose the EXIT option from the menu By default values and text are printed vertically at the cursor position For annotation of a plot this is inconvenient if c h is used then the output is horizontal 4 1 7 Useful functions in GENIE As well as the built in functions of GENIE there are some routines that are specific to TOSCA that are useful to know about For most of the TOSCA User Guide 44 66 programmes when prompted for a workspace type w 1 lt lt 16 Exceptions will be noted QR4 This is to have a look at the spectrum as
4. Figure 2 14 Testing the sample with B top and y bottom radiation monitors 4 MONITOR the sample with both B and y monitors B monitor cap off see Figure 2 14 If the radiation level is less than 75 uSv consign the sample to the TOSCA active sample cupboard If the levels are greater than 75 uSv inform the Duty Officer for instructions ext 6789 Samples consigned to the active cupboard MUST be in sealed plastic bags and labelled with the owner s and sample names and date The sample environment form should also be included Spare bags are in the tool cupboard and the prep labs Note f you really must transfer active loose powders between sample holders or if a sachet bursts accidentally phone the Duty Officer for instructions and help NO SAMPLES MAY BE REMOVED FROM ISIS WITHOUT THE CONSENT OF HEALTH PHYSICS 2 7 Removal of a Stuck Centrestick Occasionally during removal from the CCR a centrestick is found to be stuck in the cryostat There are a number of possible causes of this of which the most common are failure to ensure that the centrestick is dry when it goes TOSCA User Guide 27 66 into the cryostat a leak around the top flange of the centrestick caused by the flange being incorrectly seated on the O ring or if the sample was pre cooled in liquid nitrogen solid nitrogen gluing the lowest baffle to the cryostat wall By whatever means the usual result is a small amount of air or nitrogen condensing between th
5. gt 2 gt 4 Type user input in bold gt gt smo lt The screen returns gt gt TOSCASDISKO TOSCA COMMAND SMOOGEN gt gt gt gt Data smoother using Savitzky Golay method gt gt gt gt ENTER WORKSPACE 1 For the workspace type the workspace number not w The screen returns gt gt Workspace to be smoothed 1 gt gt SMOOTHING 10 This controls the degree of smoothing any integer 1 100 is usuable but 10 is a reasonable compromise between noise reduction and loss of resolution The screen returns gt gt Percentage of smoothing 10 gt gt ENTER ORDER 0 2 4 4 This also affects the quality of the ouput 4 works well for smoothing a background The screen returns gt gt Smoothing polynomial order 4 gt gt TR W1 TOSCASDISKO TOSCA COMMAND SMOOGEN EXE W1 No OF DATA POINTS 1109 No OF WINDOW POINTS 111 POL ORDER 4 If the result is not to your liking copy the original data to another workspace and experiment with the smoothing and the polynomial degree until you get something you do like SPIKE TOSCA User Guide 50 66 Occasionally a spectrum will contain a spike in the data caused by a glitch in the detector or DAE electronics There are two ways of dealing with this convert the file to ASCII using B2A edit out the offending points and then put it back into GENIE with LOAD_B2A Alternatively it can b
6. B2A TOSCA DISK0 TOSCA COMMAND Jb2a Converts binary files into ASCII CON TOSCA DISK0 TOSCA COMMAND CONVERT Conversion of X scale from meV to cm DER TOSCA DISK0 TOSCA COMMANDJDERIVATIVE Double derivative of a workspace GAUS TOSCA DISK0 TOSCA COMMANDJNGAUS Gaussian fits prog T Perring LOADB2A Loads 3 column x y e ASCII file LPR TOSCA DISK0 TOSCA COMMANDJLASER_PLOTS COM Screen capture and print STR TOSCA DISK0 TOSCA COMMANDJSTRETCH Stretches compresses the X scale by requested factor SMO TOSCA DISK0 TOSCA COMMAND JSMOOGEN Smoothing using Savitzky Golay method SPIKE TOSCA DISK0 TOSCA COMMANDJSPIKE Spike removal COMP TOSCA DISK0 TOSCA COMMAND COMP Correction for misaligned sample 64 66 TP TOSCA DISKO0 TOSCA COMMAND JTEMP_PLOT CO M TPC TOSCA DISK0 TOSCA COMMAND TEMP_PLOT_C URRENT COM Temperature plotting of current or old data ZERO TOSCA DISK0O TOSCA COMMAND JZERO_ERRO RS Sets all error values in a workspace to zero MUPHIP TOSCA DISK0 TOSCA COMMAND JMUPHIP C OM DENSIP TOSCA DISK0 TOSCA COMMANDJDENSIP CO M DAMP TOSCA DISK0 TOSCA COMMAND DAMP COM ERA TOSCA DISKO0 TOSCA COMMANDJERA COM FR4 TOSCA DISK0 TOSCA COMMAND FOREHACKS3B COM Conversion of time of flight to energy transfer SR4 TOSCA DISK0 TOSCA COMMAND JFOREHACKSU M3B COM Co addition and conversion of sequential time of flight files to energy
7. The home numbers can be used in the case of problems in the evening but please not after 11 o clock except for dire emergencies The Main Control room is manned at all hours and they can also be contacted if you have a problem ext 6789 If you have queries about accommodation claims or transport contact the University Liaison Office ULS inside working hours ext 5592 email isisuo rl ac uk To dial an office extension from outside RAL 01235 44 extension number To make an external call from a RAL phone normal number Other useful numbers Emergency Fire or Ambulance 2222 Main Control Room 6789 Health Physics 6696 University Liaison Office 5592 6 4 Safety summary Before you start your experiment please make sure that You have registered with the University Liaison Office ULS in R3 or in the Main Control Room MCR if you arrive outside working hours If you are a new user you will be issued with safety instructions read them You must also watch the safety video and sign the yellow card You have picked up a film badge from the Health Physics Office opposite the MCR and a swipe card from the MCR You have picked up and read the sample record sheet from the Data Acquisition Centre DAC and that you understand the sample handling instructions This sheet is to be displayed on the instrument during the experiment The full safety instructions are to be found in the literature given out by the ULS However the sali
8. a few minutes to close Figure 2 8 The shutter controls in the TOSCA cabin 3 Ensure the shutter is closed Wait until both the blue fluorescent light and the red Beam On sign are off and the green CLOSED light is illuminated in the shutter control panel The radiation monitor on the wall of the target station must show a green light and a reading of less than 20 u Sv hr Figure 2 9 TOSCA User Guide 20 66 Figure 2 9 The radiation monitor on the target station wall TOSCA s is labelled N8 TFXA upper right 3 Turn anti clockwise the Red i e carrying a red tag key in the Green box and release it Engage the Red key in the Blue box and turn it clockwise This liberates all other keys in the Blue box Select any other key and turn it anti clockwise and remove it Remove the shielding from the top of the cloche Place the key in the enclosure lock and turn it anti clockwise Rotate the bolt fully and withdraw the bolt fully and withdraw Open fully the small brass valve on the flowmeter to the helium cylinder see Figure 2 6 Do not adjust the regulator the gas pressure on the gauge should read about 0 5 bar 10 Open valve No s 1 2 and 4 on the cryostat pump see Figure 2 10 The vacuum gauges should show the pressure rising slowly meanwhile the He gas flow is at maximum Ensure that the light blue valve on the CCR is pointing vertically Figure 2 13 of OND TOSCA User Guide 21 66
9. crashes the batch job should restart using lt filename gt the command file is terminated To check on the status of the command file use sho que toscaSbatch The response will be Batch queue TOSCASBATCH available on TOSCA Entry Jobname Username Status 1767 JIAN TOSCA Executing where Jobname is the name of the command file To stop a batch job type del entry xxxx lt where xxxx Is the entry number returned by the sho que command 1767 in this instance 3 5 Using the 24 position samplechanger The 24 position samplechanger can be used either manually or under TOSCA User Guide 36 66 computer control In both cases the initial setting up procedure is the same The samples are arranged on an endless chain and the can at the top of the samplechanger is viewed through the Perspex window DO NOT CLEAN WITH SOLVENT by a webcam The samples are tracked by the numbers on the clamping plate This consists of six digits a four digit number and a two digit checksum Thus in Figure 2 4 the number 003205 is visible so this is 0032 and 0 0 3 2 05 When a sample is in the beam the can number is not visible but its counterpart 12 positions away is visible Thus the first operation after loading the samples onto the samplechanger see section 2 4 is to create a table of sample can number and can number at the top when the sample is in the beam An example is Can Top Sample 2507 707 0 5 mm cell H2O 2
10. houses the beryllium filters Both of these are pumped with turbomolecular pumps to a cryogenic vacuum of better than 10 mbar The sample and beryllium filter tanks on TOSCA are separated by aluminium windows The spectrometer vacuum pumps are located beneath the spectrometer access is interlocked The vacuum gauges see Figure 5 1 and controls for the pumps are in the electronics cabinet on the mezzanine level in front of the TOSCA services panel on the side furthest from the target station see Figure 2 3 The upper panel is for the beryllium filter and the lower panel is for the sample environment tank The display is in millibar You will NOT normally touch any of this equipment however it is good practice to check the pressure in the two systems once or twice a day TOSCA User Guide 55 66 If the pressure is greater than 1 x 10 mbar you should inform your local contact immediately TOSCA ANALYSER MODULE VACUUW arian rune Current Teurena une rower m ai gt E Turbo V 250 a Figure 5 1 The vacuum gauges on TOSCA 5 1 2 The Beryllium Filters The transmission of a beryllium filter is approximately doubled by cooling below 100K On TOSCA each Be filter is attached to a single stage CCR that cools it below 50K The ten CCR heads are driven by five compressors that are located outside the hall adjacent to the nearest exit from R55 see Figure 5 2 The temperature of the heads is measu
11. of the two sets of detectors back forward These are called trsl sum of back and forward detectors trslba backscattering detectors trslfo forward scattering detectors To read in an analysed file type r wl tosca user trsIxxxx ana r wl tosca user trslbaxxxx ana r wl tosca user trslfoxxxx ana For the total back or forward scattering detectors respectively where Xxxx is the run number For TOSCA 1 run numbers 1 2134 there are only backscattering spectra so only the first command is applicable For TFXA spectra use r wl tfxa user trslxxxx ana To display a spectrum assumed stored in workspace 1 type gt d wl This will plot the spectrum in the GENIE graphics window The range of data displayed may be specified TOSCA User Guide 41 66 d wl 50 100 0 1 0 3 This plots workspace 1 between 50 and 100 x units and 0 1 and 0 3 y units GENIE assumes that the two numbers following the workspace number are x values to specify a y range an x range must be given first 4 1 2 Types of plot As well as the histogram plot it is also possible to plot the data as points line plots or error bars To change the type of plotting type d I Fora line plot d h For a histogram plot d e For error bars d m lt For the data points The display defaults to the last of these options entered 4 1 3 Overlaying spectra To overlay spectra one on top of another yo
12. plugged in and switched on In the TOSCA cloche the heavy black cable must be plugged into the socket marked HTR on the same black box to which the temperature sensor lead is attached The heater on off switch is on the Eurotherm crate in the electronics rack in the TOSCA cabin The of the maximum power is also controllable To determine the current setting type FEM gt cshow max_power engq The computer will return Value returned was xx Where xx is the power To change this value type FEM gt cset max_power Where is the desired value 0 lt lt 100 TOSCA User Guide 33 66 3 3 Data collection commands All the following instrument control commands may be abbreviated to three letters begin update store pause resume abort end Starts a run Stores the data collected so far in the current run parame CRPT Stores the data collected up to the last update in the file tosca disk0 tfixmgr data TSCAQ lt xxxx gt sav Tl command should always be preceded by an update Pauses data collection Resumes data collection Aborts the current run without saving any data Ends the current run and stores the data in TOSCASdiskO tf xmgr data TSCO lt xxxx gt raw The analysed automatically by a batch program when a run is process takes a few minutes after that it can be viewed u 3 4 Using command files Command files are written to control the instrument An example is begin begins ru
13. transfer QR4 TOSCA DISK0 TOSCA COMMAND JFOREHACKQ3 B COM To look at the data being collected 7 3 Detector Tables 7 3 1 WIRING DAT The wiring table can be downloaded here 7 3 2 SPECTRA DAT The spectra table can be downloaded here TOSCA User Guide 65 66 7 3 3 DETECTOR DAT The detector table can be downloaded here 7 4 Detector Voltages LeCroy Channel o NI DO Oo A WwW N Voltage 0 1650 1650 1650 1650 1650 1650 1650 1650 1650 1650 0 975 850 850 Channel 15 onwards are not used Page updated Comment Not used Inelastic detectors Inelastic detectors Inelastic detectors Inelastic detectors Inelastic detectors Inelastic detectors Inelastic detectors Inelastic detectors Inelastic detectors Inelastic detectors Not used Monitor Inelastic detectors Inelastic detectors Page URL http www isis rl ac uk molecularSpectroscopy tosca toscamanual htm TOSCA User Guide 66 66
14. user 6 THE VITAL STUFF TOSCA User Guide 59 66 6 1 Beam off You can check if the beam is off in a number of ways the beam current displays at both ends of the experimental hall will read BEAM OFF the Dashboard display will read zero current and your data will not improve with time You can get information on what has happened and how long the beam will be off by typing in the TOSCA Control window TOSCA gt ISISNEWS C e You exit by pressing Control Y The beam statistics can be checked via the internet At http www isis rl ac uk there is a link to a page containing information about the beam status From here graphs of the beam current can be obtained There is a link to the MCR message board containing repair information and estimated fix times 6 2 A final checklist Before you walk out of the cabin for a quiet night in the pub quickly go through the following checklist Interlocks complete Shutter open Vacuum good Be filter temperature s lt 50K Command file e g for temperature changes edited stored and running Dashboard shows RUNNING or possibly WAITING if using a command file 6 3 Useful phone numbers In the event of any problems with the instrument computing or sample environment your first point of contact should be your local contact If they are unavailable then you should contact Stewart Parker Timmy TOSCA User Guide 60 66 Ramirez Cuesta or John Tomkinson
15. very few data points available there is no visible difference between plots using the two modes see Toggle in the GENIE manual for details The data is stored in workspace 1 and can be treated as normal Note that because it was generated in GENIE it is completely volatile It can saved as ASCII data using B2A or as binary data using the GENIE write command see GENIE manual for details B2A This program converts a binary file located in a workspace into a three column ASCII file x y and error which is suitable for input to aCLIMAX CLIMAX or to a spreadsheet Type b2a lt you will be prompted for the workspace w and a filename Note that b2a automatically adds DAT to the name you give it You are then prompted for the first and last x values although it asks for the values in meV it actually uses whatever the workspace x units are cm A A 1 LOAD_B2A This program inputs an ASCII file to GENIE It assumes the same format as that created by B2A i e first line is the title second line is the units and then three space separated columns x y error To use it type gt gt load w lt filename gt tosca command load_b2a TOSCA User Guide 48 66 The syntax is load w tosca command load_b2a e g load wl 1butoh dat tosca command load_b2a If the ASCII file is not in the same directory from which GENIE was started usually TOSCA DISKO TOSCA then lt filename gt must include the comp
16. 3 03 However things change You are advised to check http www internal clrc ac uk catering restaurant Opening TimesoftheRestaurant html for the most recent information ISIS running ISIS shutdown Monday to Breakfast 7 30 9 00 7 30 9 00 Friday Lunch 11 45 13 45 11 45 13 45 Light meal 17 00 18 00 17 00 17 30 Restaurant 18 15 20 30 17 30 19 15 Weekend Breakfast 8 00 9 00 8 00 9 00 Lunch 12 00 13 30 12 00 13 30 Restaurant 18 00 20 00 Closed TOSCA User Guide 62 66 RI coffee lounge 08 30 16 00 Monday to Friday closed weekend 6 5 2 Pubs Blewbury Chilton East Hendred East llsley Steventon Wantage West Hendred West Ilsley 7 APPENDICES 7 1 TOSCA Parameters Moderator Beam size at sample Beam height Detectors Distances Moderator to chopper TOSCA User Guide The Red Lion Rose amp Crown The Plough Wheatsheaf The Crown and Horns The Swan The Cherry Tree The Fox The Lamb The Swan The Hare The Harrow H20 300K Poisoned with Gd at 2 5 cm 40 by 40 mm h x w 1165 mm from underside of flange to centre of the beam 130 He proportional counters for inelastic scattering 2 5 mm effective thickness 150 mm effective length 4 He diffraction detectors in backscattering 1 incident beam monitor scintillator 9 5m 63 66 Moderator to sample 17 0m Sample to detectors 0 7m 7 2 List of TOSCA Specific GENIE commands TOSCA User Guide
17. 810 3609 1 mm cell H2O 2103 303 2mm cell H2O 1203 404 Ti NaAlH4 fresh 505 3508 Ti NaAlH4 after TPD 1405 3306 Ti NaAlH4 after 10 bar H2 202 1910 Ti NaAlH4 after 100 bar H2 2709 3003 Sn NaAlH4 fresh 1506 2204 Sn NaAlH4 after TPD 2406 101 Sn NaAlH4 after 10 bar H2 2911 2002 Sn NaAlH4 after 100 bar H2 808 2608 n propanol 707 2507 3609 2810 303 2103 404 1203 3508 505 3306 1405 1910 202 3003 2709 2204 1506 101 2406 2002 2911 2608 808 Note that not all the positions need to be filled but pairs of cans must both have numbers After creating the table the cables are removed and the samplechanger is then loaded into TOSCA using the crane this must be done by the local contact Note the samplechanger must be bolted down before evacuating the IVC After installation the main control cable the Ethernet cable and the power supply for the webcam and the thermometer cable are reconnected Figure 3 3 shows the samplechanger installed in TOSCA and the important points TOSCA User Guide 37 66 highlighted Figure 3 3 The samplechanger installed in TOSCA Before setting the interlocks it is wise to check that everything is working The lights immediately below the webcam should be on and the sample in lock light on the controller Figure 2 5 and on the samplechanger indicated on the right hand side of Figure 3 3 should be illuminated The webcam should also be working This can be viewed in th
18. CA gt change lt can be abbreviated to cha will initiate the Dashboard editor Move between areas using the up and down cursor keys and over type There are six pages you will only modify the first This page contains title and user information When entering the title please be informative abbreviations or sample numbers are not helpful The accumulated spectra on TOSCA form a unique library whose usefulness is compromised if the spectra are not clearly identified To exit press PF1 found on the numeric keypad on the right of the keyboard A prompt will appear at the top of the screen to exit press efe 3 2 Setting sample environment parameters The top right hand portion of the Dashboard displays the sample environment parameters sample temperature normally TEMP and cryostat temperature normally TEMP1 If you have changed centresticks or are using a sensor attached to the sample rather than the one built into the centrestick you will need to input the sensor number Each sensor is individually calibrated and a unique four digit number is written on the sensor On each centrestick is a label with SEN on it that gives the sensor number To check the censor number type TOSCA gt cshow temp full or temp1 The computer will respond Sample environment block TEMP has flags res act set SE block name TEMP Requested value 5 000 Exponent Units KELVIN Low trip value 2 000 High trip value Current value 17 600 Yalidity T
19. Converted value Run control F Logging T Stability Monitor period 0 Crate address 0 Crate subaddres System offset 0 000 Register group 0 Preprocessor Display formati Display format2 Device number Command file Display 7 T Channel number Secondary block SETER The Device number is the sensor number To input a different sensor number type TOSCA User Guide 32 66 TOSCA gt cset temp devspc xxxx Where xxxx is the sensor number Most spectra are recorded at the base temperature of the cryostat If other temperatures are required then cartridge heaters need to be attached to the sample before it is loaded into the cryostat To change the sample temperature the cset command is used as follows TOSCA gt cset temp value 100 control will set the sample temperature to 100K Limits can be set to ensure that data are only collected between specified temperatures TOSCA gt cset temp value 45 lolimit 40 hilimit 50 control will ensure that data is only collected while the sample temperature lies between 40K and 50K If the sample temperature strays out of these limits the instrument will be put into WAITING mode If run control is no longer required the nocontrol qualifier should be used TOSCA gt cset temp nocontrol When measurements are to be made at base temperature the heater is usually switched off If you want to warm up the sample and there appears to be no response to the cset temp command check that the heater is
20. OSCA terminal in the cabin For screen 1 two DECTERMS are needed At the TOSCA gt prompt type TOSCA gt stat on e lt means press enter and the Dashboard will appear Figure 3 2 The useful data in the screen are The run number at the top right The instrument status in the centre this can be SETUP for changing samples RUNNING for collecting data or WAITING for a control parameter usually the temperature to be true The user name s and sample title are at the left halfway down Below this is the ISIS beam current to the target and on the same line is the total microamps Total uA received in the current run For adequate statistics from a hydrogenous sample this should be at least 600 3 4 hours runtime small samples or non hydrogenous ones will require considerably longer On the right is the sample temperature TEMP in Kelvin below this is the cryostat temperature TEMP 1 in K The second window is the TOSCA control window which should only be used for control commands such as beginning updating and ending runs changing temperature and starting instrument control command files This terminal should be left in the tosca disk0 tosca area at all times Note Do not leave files in the tosca disk0 tosca area that you want to keep The area is regularly purged TOSCA User Guide 31 66 3 1 Change The change command allows the user to edit the Dashboard information Typing the command TOS
21. PLAY Displaying histogram workspace in point mode Displayed using bin grouping of 1 fy A l Y 4 J Mig ed 200 400 Energy Transfer AE E1 E2 em ess ay es one is cw a L gt T as Foz spe fat oE Figure 4 1 The OPENGENIE control window and display window To plot the spectrum the lpr command is used as in GENIE type lpr This will print the list of printers given in Table 4 7 and ask which printer to use Just type the printer number and a postscript file will be automatically created and sent to the nominated printer To look at previously analysed files type we get 1 tosca user trslxxxx ana w get 1 tosca user trslbaxxxx ana w get 1 tosca user trslfoxxxx ana TOSCA User Guide 54 66 is any integer and xxxx is the run number To use the cursor type cursor at the prompt rather than just c as in GENIE Further TOSCA utilities will be added as time enthusiasm and demand enable 5 THE HARDWARE ON TOSCA The purpose of this section is to supply practical information on where things are on TOSCA and how they work It also supplies information on what the user can attempt without the risk of damaging the instrument and what should be left to the instrument scientist 5 1 The Instrument 5 1 1 The Vacuum TOSCA has two separate vacuum systems the sample tank that contains the cryostat and a second vacuum system that
22. TOSCA User Manual CONTENTS PREFACE 1 INTRODUCTION 1 1 Description of the instrument and basic INS theory 1 2 Sample environment on TOSCA 2 SAMPLE HANDLING 2 1 Safety 2 2 Preparing samples 2 2 1 Preparing an aluminium sachet 2 2 2 Preparing a liquid can 2 3 Loading the samples onto a centrestick 2 4 Loading the 24 position samplechanger 2 5 Changing sample 2 6 Removal from centrestick 2 7 Removal of a stuck centrestick 3 CONTROLLING THE INSTRUMENT 3 1 Change 3 2 Setting sample environment parameters 3 3 Data collection commands 3 4 Using command files 3 5 Using the 24 position samplechanger 4 DATA ANALYSIS AND VISUALISATION 4 1 GENIE 4 1 1 Looking at analysed files 4 1 2 Types of plot 4 1 3 Overlaying spectra 4 1 4 Binning and rebinning 4 1 5 Hard copies 4 1 6 Using the cursor 4 1 7 Useful functions in GENIE 4 1 8 Assigning files 4 2 OPENGENIE 5 THE HARDWARE ON TOSCA 5 1 The instrument 5 1 1 The vacuum 5 1 2 The beryllium filters 5 2 The top loading CCR 5 3 The Nimonic chopper 6 THE VITAL STUFF 6 1 Beam off 6 2 A final checklist 6 3 Useful phone numbers 6 4 Safety summary 6 5 Eating and drinking 6 5 1 On site 6 5 2 Pubs TOSCA User Guide 1 66 7 APPENDICES 7 1 TOSCA parameters 7 2 List of TOSCA specific GENIE commands 7 3 Detector Tables 7 3 1 SPECTRA DAT 7 3 2 WIRING DAT 7 3 3 DETECTOR DAT 7 4 Detector voltages PREFACE This document is designed as an aide
23. The can consists of two outer cases and a spacer The spacer thickness can be varied between 1 and 10 mm The can is sealed using either indium wire narrow grooves or with Viton O rings wide grooves Since the width of the can is much greater than that of the beam solid samples should be loaded into a TOSCA User Guide 14 66 sachet and this positioned in the centre of the can before assembly To reduce scattering from the cell it should be completely shielded with cadmium apart from the opening at the front of the cell Owing to the large mass of the cell once loaded and attached to the centrestick it should be immersed in liquid nitrogen for a few minutes immediately prior to putting the centrestick in the cryostat This reduces the cool down time to less than an hour from several hours Figure 2 2 The components of a liquid cell and an assembled cell shielded with cadmium mounted on a centrestick 2 3 Loading the samples onto a centrestick For solid samples in sachets the simplest method is to attach the sachet to the aluminium baseplate of an HET type can lower left in Figure 2 2 with small strips of aluminium sticky tape The beam centre is 1165 mm below the underside of the centrestick flange and the beam itself is 40 x 40 mm h x w The sample should cover as much of the beam area as possible and be preferably no more than 2 mm thick If measurements at temperatures other than the base temperature of the CCR 12K are int
24. The commands are next_sample moves forward number of samples set in Steps prev_sample moves back number of samples set in Steps prev_sample is not recommended as explained earlier To ensure reproducible positioning it moves back two positions then forward one so that the limit switches on the samplechanger are always struck from the same direction The commands are treated the same as any other VMS command so can be included in a command file as usual 4 DATA ANALYSIS AND VISUALISATION Several programs and utilities exist to help you analyse your data including the GAUS least squares fitting program TOSCA is unusual in that for most cases the output from the automatic analysis program is all that is required However if desired the raw time of flight data can be analysed independently If you are doing data analysis in your own directory make sure that you are using the TOSCA GENIEINIT COM Please do not log onto TOSCA and start GENIE as this seriously slows the system use a different computer instead e g ISISA 4 1 GENIE GENIE is the language used at ISIS for data manipulation A full description of which is available in the PUNCH user manual a copy of which resides in the TOSCA cabin Additional copies may be obtained from the computer support office If you are in the TOSCA cabin the GENIE window on screen two should already be opened If there is no GENIE window or if GENIE crashes rare but not unknown it is r
25. a into 2 cm intervals between 16 and 4000 cm Rebin truncates to the limits given Thus if the upper limit was 2000 cm then the data would only be retained between 16 and 2000 cm Note that multiple ranges are possible as shown in the second example In form 2 with brackets the value inside the brackets is related to the size of the time bins in the raw time of flight data When the data is transformed from time of flight to energy transfer a value of 0 005 is used across the entire spectrum Thus in form 2 the spectrum is being rebinned in 4 s 0 02 4 x 0 005 between 16 and 200 and in 1 s between 200 and 4000 cm This is a particularly useful form of the command since at low energies there are many more data points than can be justified by the instrument s resolution function Thus the data can be rebinned to improve the signal to noise without degrading the resolution 4 1 5 Hard copies To obtain a hard copy of the current data that is displayed in the GENIE graphics window type lpr A list of printers is then given and you are prompted for which printer to use See Table 4 1 Just type the printer number and a postscript file will be automatically created and sent to the nominated printer Laser printers Location TOSCA User Guide 43 66 LASER 0 Computer support office R3 LASER 1 Coffee room R3 LASER 2 DAC R55 LASER 17 TOSCA cabin Table 4 1 A list of the normally used printer devices
26. ae T T Cooled beryllium filter Graphite analyser Neutrons Sample a IE Figure 1 2 A section through one of the analyser modules of TOSCA The source of neutrons on TOSCA is the white beam from the water moderator The time of flight technique is used for energy analysis of the scattered neutrons A small fraction of the incident neutrons are inelastically scattered by the sample those that are backscattered through an angle of 45 or 135 impinge on a graphite crystal Bragg s law states 2dsin0 1 where d A is the interplanar distance in the crystal A A is the wavelength of the scattered neutron and is the angle of incidence on the crystal From equation 1 since both d and 6 are constant only one wavelength and its higher orders A 2 A 3 etc will be Bragg scattered by the crystal the remainder will pass through the graphite crystal to be absorbed by the shielding The neutrons at multiples of the fundamental wavelength are scattered by the beryllium filter which acts as a longpass filter and the remaining neutrons are then detected by the He filled detector tubes The net effect of the combination of the graphite crystal and beryllium filter is to act as a narrow bandpass filter The energy transferred to the sample Erans iS TOSCA User Guide 5 66 Etrans E z E 2 where E and E are the incident and final energies respectively The kinetic energy E of a neutron is given by a
27. at some energy there will be less than one time bin per energy element which results in a computer error Type of output 1 for double differential 2 for S Q w usual choice 3 for both 4 for neither Whether to exclude any detectors Only in exceptional circumstances would this be required e g single crystal studies For most samples the detectors are evenly illuminated thus excluding detectors results in a reduction in signal to noise If detectors are to be excluded type 1 and then either 1 include or O exclude for each detector in turn FR4 then analyses the data like QR4 it uses workspaces w1 w9 and puts the data in w5 w7 and w9 at the end of the analysis It also writes the analysed data to toscaSdisk0 tosca user trslxxx ana toscaSdisk0 tosca user trslbaxxx ana toscaSdisk0 tosca user trslfoxxx ana so it may be read in subsequently TOSCA User Guide 46 66 Thus to analyse data using the standard conditions the series of inputs are aL eS 1 lt 005 Value must be in this format 0 005 will not work SR4 This program analyses spectra that were collected sequentially and co adds the result The co addition is performed before the data is converted to energy transfer since this results in slightly better statistics The operation is the same as for FR4 except that the user is prompted for the number of spectra and the first run number It writes the analysed data to toscaSdisk0 tosca u
28. cident flux distribution as a function of time and is used to normalise the spectra Further reading TOSCA User Guide 7 66 There is more information about TFXA and TOSCA at the Molecular Spectroscopy website http www isis rl ac uk MolecularSpectroscopy This includes a list of publications resulting from work on TFXA and TOSCA There is also a database of INS spectra that have been obtained on the instruments Two types of ASCII and two types of image files are available for downloading The database is at http www isis rl ac uk INSdatabase D Colognesi M Celli F Cilloco R J Newport S F Parker V Rossi Albertini F Sacchetti J Tomkinson and M Zoppi TOSCA neutron spectrometer the final configuration Appl Phys A 74 Suppl 2002 S64 S66 A description of the current version of TOSCA S F Parker C J Carlile T Pike J Tomkinson R J Newport C Andreani F P Ricci F Sachetti and M Zoppi TOSCA A World Class Inelastic Neutron Spectrometer Physica B 241 243 1998 154 156 This paper gives an overview of TOSCA S F Parker Vibrational Spectroscopy With Neutrons Spectroscopy Europe 6 1994 14 20 This gives a brief description of TFXA and highlights some of the areas of research on the instrument J Tomkinson The Vibrations of Hydrogen Bonds Spectrochimica Acta 48A 1992 329 348 Illustrates the application of INS to hydrogen bonding studies G J Kearley A Review of the A
29. d attached to a centrestick see section 2 2 Preparing samples Liquid samples are run in thin walled aluminium cans Air or moisture sensitive samples solid or liquid should be loaded into the cans in a glovebox As explained in the previous section to maximise the INS intensity it is necessary to reduce the Debye Waller factor as much as possible thus virtually all samples on TOSCA are cooled Cooling below 50K makes little difference to the spectrum thus a Closed Cycle Refrigerator CCR which attains temperatures below 20K region is adequate for most samples see Figure 1 3 This has the virtues of being reliable cheap to run and simple to operate The CCR is isolated from where the sample sits and uses helium exchange gas to cool the sample This has the advantage that the sample can be changed without warming the CCR thus samples can be changed in a matter of minutes without difficulty see section 2 5 Changing a sample The TOSCA CCR has a an internal diameter of 100 mm so will take standard ISIS centresticks In addition there are a number of dedicated centresticks for special applications The most important of these is the 24 position automatic samplechanger This is described in detail in section 2 4 and 3 5 If temperatures below the base temperature of the CCR 20K are required then normal ISIS practice would be to replace the CCR with a liquid helium cryostat orange cryostat Because of space constraints this is not poss
30. e TOSCA cabin using the Ray of Light programme on the PC next to the VMS screen see later or at http eye2 nd rl ac uk java on the general use PC It should be listed under Favourites in Internet Explorer The chain of command is VMS Ray of Light controller samplechanger The samplechanger can be operated from any point along the chain although full automation is only possible from VMS The Ray of Light interface is shown in Figure 3 4 TOSCA User Guide 38 66 ISIS Ray Of Light Instrument Control Program 5 RUN RB Number User Title Tue 11 Mar 2003 11 52 07 Te Current run time IcoodjRaw Frames Current Total 4A AE bytes Monitor Period Spectrum rom mms Periods ro mms Channels Counts Krypton Argon Osmium Tantalum Copper im Hydrogen iE Helium C Palladium Berylium Carbon E 3 Nitrogen Sample name 0360S Palladum _ Bervlium 3 Carbon S Nitrogen 2 Palladium Sodium Zinc IS Uranium S lodine 1O1 Oxvaen Chlorine S INeon Krypton Argon 3 Osrium Tantalum Copper IS Hydrogen Helium Enter Zebadee Command Message Received From CAMAC Reply Sent to CAMAC Command Cache Timeout CAMAC Figure 3 4 The Ray of Light i
31. e baffles of the centrestick and the cryostat wall In these cases warming the cryostat to 90K is sufficient to free the centrestick If ice is present then it is necessary to warm it to near room temperature THE FIRST ACTION SHOULD BE TO INFORM YOUR LOCAL CONTACT The sequence of actions is 5 6 11 Fill the centrestick chamber with helium gas The flange of the centrestick must be bolted down Switch off the two CCR compressors labelled TOSCA on the ground floor by the outer wall of R55 inside the hall Figure 2 15 DO NOT TOUCH the five compressors that are outside the hall Figure 5 2 Warm the cryostat to 90K When the sample temperature is 90K attempt to remove the centrestick as normal see section 2 5 If the centrestick cannot be removed wait until the cryostat has reached room temperature When the centrestick has been removed replace the blanking flange and flush the sample volume with helium gas three times before installing the next sample Re start the CCR compressors TOSCA User Guide 28 66 20K sample environment compressor Figure 2 15 TOSCA CCR compressors inside the hall Right 40K cold shield compressor left 20K sample compressor 3 CONTROLLING THE INSTRUMENT TOSCA is run by a DEC ALPHA 500 computer located in the TOSCA cabin on the mezzanine level of R55 After logging on if necessary the screen will look like Figure 3 7 In the centre of the toolbar at the bottom
32. e done using SPIKE which draws a straight line between two user defined points Display the spectrum and using the cursor note the edges of the region to be removed The sequence of commands is user input in bold gt gt spike gt gt TOSCASDISKO TOSCA COMMAND SPIKE COM gt gt gt gt Getting rid of spikes gt gt gt gt ENTER INPUT WORKSPACE NUMBER 1 gt gt Workspace to be cured 1 gt gt ENTER OUTPUT WORKSPACE NUMBER 5 gt gt Cured workspace 5 gt gt first x axis point 1355 gt gt First x axis point gt gt last x axis point 1390 gt gt Last x axis point gt gt W5 W1 Load Workfile 1 into Workfile 5 gt gt TR W5 TOSCASDISKO TOSCA COMMAND SPIKE EXE W5 No OF DATA POINTS 996 COMP This programme corrects for a misaligned sample If the sample is not at the centre of the instrument i e it is displaced toward or away from the moderator this results in a shift in the spectral positions that increases linearly with increasing energy transfer This manifests as the peaks in the forward and backscattering spectra appearing at different positions The commonest cause is samples being mounted proud of the aluminium frame on the samplechanger If the shift is small then the peaks are broadened if it is large the peaks may be doubled It is good practice to always overlay the forward and backscattering spectra to check for a misalignment rather than ju
33. e started by typing GENIE upper or lower case are both OK since VMS is case insensitive in a DECTERM window see section 3 and Figure 3 1 for how to start a window This will create an additional window that can be re sized using the mouse By default GENIE only uses the current screen it does not scroll and allow you to use the scroll bar on the right of the window This is inconvenient and can be corrected by clicking on the word COMMANDS at the top of the window and selecting the last item in the list RESET TERMINAL If you are not in the cabin and are attempting to work on TOSCA data TOSCA User Guide 40 66 elsewhere e g in the DAC the procedure is more complicated and you should consult your local contact before starting When GENIE starts a page will scroll past which includes each specialised function available and the command needed to utilise them For reference a copy of this can be found in section 7 2 Typing the command sho sym will type the list On TOSCA GENIE is divided into 16 workspaces w1 w16 The data in GENIE is completely volatile and does not alter the original data on the TOSCA disk Thus no operation up to and including crashing GENIE will result in loss of data 4 1 1 Looking at analysed files For each run three analysed i e as intensity vs energy transfer files are stored These are the the summed back scattering detectors the summed forward scattering detectors and the sum
34. ended then the best method is to attach heaters and a sensor to the sides of the plate Note the sensor number Care should be taken that only the sample and the Al sachet are in the beam items such as sensors heaters tape or wire should not intrude If it is intended to measure more than four samples at base temperature it is worth considering using the 24 position samplechanger For six or more its use is almost mandatory Samplechanger type liquid cells are held by a clamp attached to the end of the centrestick see Figure 2 14 HET cans have a mounting plate with an M8 screw that attaches to the end of the centrestick top in Figure 2 2 2 4 Loading the 24 position samplechanger The 24 position samplechanger is shown in Figure 2 3 it consists of two parallel endless chains connected with horizontal bars from which the samples are suspended The device can be controlled either manually from a handset attached to the control box in the electronics rack next to the services panel or under computer control The latter is described in section 3 5 Note that samples can only be run at TOSCA User Guide 15 66 the base temperature of the cryostat 20K with the samplechanger it is not possible to put heaters on the sample or to heat the cryostat You should also assume that the samplechanger can only be run forwards so the samples should be loaded in the order in which you wish to run them Figure 2 3 The 24 position samplechanger in
35. ent points concerning the instrument are summarised here After the experiment the sample should be monitored If the radiation is Greater than 75 uSv beta or y The ISIS duty officer ext 6789 must be informed to supervise the removal of the sample Any operation concerning the sample must also be supervised by the duty officer Greater than 10 uSv The sample can be removed and stored in the active sample cabinet However any operation that requires the sample can to be opened must be done in an active glove box TOSCA User Guide 61 66 Less than 10 uSv The sample can be handled normally using good laboratory practice After the completion of the experiment the sample can and sample should be placed in the active sample cabinet in a suitable container with a copy of the sample record sheet If it is necessary to transport an irradiated sample off site documentation must be obtained from the health physics office Do not take the sample to them they will come down to the instrument Preparing the documentation will take some time so ask for this well in advance of departure ISIS conforms to COSSH regulations Any chemical process or procedure that involves chemicals must be assessed beforehand by ISIS Safety personnel If you have any safety concerns ask your local contact or ring the Main Control Room 6 5 Eating and Drinking 6 5 1 RAL Opening Hours R22 Restaurant The times below were correct at 26
36. es a given temperature This can usually be estimated fairly accurately and a command file with a WAIT statement used Alternatively the cset command with the control option can be used but data is not collected while in the WAITING state Instead if the chklog option is used with cset then the next command is only executed when the condition is true A sample command file is cset temp value 20 lolimit 5 hilimit 25 sets temperature limits S begin cset temp chklog waits until the temperature is in the range 5 25K end TOSCA User Guide 35 66 end run change title Sample at 20K tT begin begins new run exit This will collect data until the temperature is in the range 5 25K when it ends the run changes title and starts a new run The commonest use for this command is while waiting for the sample to cool but it is not the only possible use Command files are created using the VMS editor and end with the extension com They are run from the TOSCA Control window using lt filename gt To interrupt a command file type Control Y Note that you are unable to use the window when a com file is running A better way to run a command file is to submit it toTOSCASBATCH by submit que toscaS batch The advantages are that your local contact can interrupt it and modify it remotely if necessary this is not possible if lt filename gt is used Also in theory at least if the TOSCA computer
37. essel to 12K The sample is cooled by helium exchange gas in this vessel As described in section 3 the cryostat and sample temperature s are displayed on the Dashboard The CCR heads are driven by the two compressors located inside the hall on the outer wall on the ground floor of R55 see Figure 2 15 If the sample or cryostat temperature starts to rise unexpectedly you should Check whether the sample or cryostat is being heated Check that there is He exchange gas in the cryostat there is a gauge on top of the cryostat see Figure 2 13 Check that both compressors are on If in doubt contact your local contact 5 3 The Nimonic chopper The Nimonic chopper on TOSCA at 9 5 m has two purposes it removes the y flash y rays and unmoderated fast neutrons from the proton beam hitting the target which only contribute to background There is a piece of BaC on the leading edge of the chopper that removes slow neutrons from the neutron pulse preventing frame overlap The chopper is phased to remove as many high energy neutrons as possible The main electronics and power supply are on the ground floor underneath the TOSCA cabin and the controls are in the rack in the partioned part of the cabin see Figure 5 3b The rotation rate should be 50 Hz and this is indicated by the digital display on the control rack If this reads anything other than 50 inform your local contact Neither the phase nor the rotation rate should be altered by the
38. ets stuck in the instrument 2 1 Safety There are a number of safety issues associated with work at ISIS The most obvious is the radiation hazard from the neutron beam and from irradiated samples and sample environment equipment This is minimised by the use of interlocks monitoring the radiation levels and appropriate handling and storage of irradiated materials If in doubt ask your local contact Health Physics or the Main Control Room Before you start an experiment you must watch the ISIS safety video in either the DAC or the coffee room in R3 and sign the yellow card There is also the risk of exposure to chemicals in this case the handling instructions on the back of the sample sheet state the required procedures to follow Note that cadmium metal is toxic it also activates in the beam so should be handled with care On removal from a cryostat samples and centresticks are usually very cold so should not be handled without gloves Some of the sample environment equipment is heavy or bulky so should be carried with due respect 2 2 Preparing samples The laboratory s official handling instructions will be found on the back of the sample requirement form You are required to observe them For solids the easiest way to present the sample is to load it into an aluminium foil sachet These are constructed as described in section 2 2 1 For liquids a thin walled aluminium can is used The same containers can be used for air or moistu
39. gripped on the centrestick as usual 4 If you are using sachets on the samplechanger ensure that they will fit within one of the aluminium frames 2 2 2 Preparing a liquid cell For liquid or air sensitive samples an indium wire sealed thin walled aluminium can should be used With liquid samples the cell should be filled in a fume hood or a glovebox if sensitive to the atmosphere For air or moisture sensitive solids the sample should be loaded and the can assembled in the glovebox There are two types available One type of cell is designed to go on the 24 position samplechanger so up to 24 samples can be loaded simultaneously these can be all cans or a mixture of sachets and cans These cans use 1 mm indium wire Figure 2 3 shows one of these cells disassembled and a complete cell The cans have pathlengths of 1 2 3 or 5 mm by suitable choice of the top plate For hydrogenous liquids the 1 mm length should be used since this is sufficient sample to give an excellent spectrum in around 6 hours The cells can be used either on the 24 position samplechanger or clamped to a standard centrestick PITTI LTTE ETE IO 20 30 40 50 60 70 80 790 100 ge 120 130 140 150 160 170 ren AMANA NANSA SAAANA NANANA AAAA AAN Figure 2 1 A liquid cell for the 24 position samplechanger Left baseplate middle top plate right assembled Figure 2 2 shows the second HET type cell of thin walled aluminium sample can and its components
40. hanger that show the sample is in the correct position The digital display will have changed by 1600 To install or remove the samplechanger in TOSCA requires the use of the crane This must be done by the local contact Figure 2 5 The 24 position samplechanger controller TOSCA User Guide 17 66 2 5 Changing sample Before changing a sample familiarise yourself with the TOSCA cloche and the area around it Figure 2 6 shows the gate and interlocks to the TOSCA enclosure and highlights the location of the important items The following procedure assumes that the four position sample changer is being used If an aluminium can or other large piece of equipment e g a catalysis cell or a McWhan cell is being used then it is essential to pre cool this in liquid nitrogen immediately before insertion into the cryostat otherwise the cool down time is prohibitively long If the sample is pre cooled in liquid nitrogen then ensure that the lowest baffle does not come into contact with the liquid nitrogen because it can freeze in the cryostat and cause the centrestick to become stuck TOSCA User Guide 18 66 Figure 2 6 The TOSCA cloche and services panel showing the interlocks interlocks pump and He flow control Access to the TOSCA CCR is via the cloche located on the mezzanine floor This is interlocked by the standard ISIS key system The interlocks on the instruments are there to try to make it impossible to get close to the neut
41. ible on TOSCA Instead there is a centrestick that incorporates a liquid helium bin in its shaft The design is such that it holds sufficient liquid helium to enable a spectrum to be TOSCA User Guide 9 66 recorded see Figure 1 3 It may also be pumped on to give a base temperature of 1 5K It is available for use but must be requested well in advance of the experiment a minimum of two weeks and ideally on the proposal form Figure 1 3 The liquid helium centrestick for use on TOSCA For pressure experiments there are two options For pressures up to 4 kbar the helium intensifier should be used This allows relatively large samples the can is 7 mm diameter x 40 mm long to be used and the pressure can be adjusted with the centrestick in the beam For higher pressures the McWhan clamped cell is used The McWhan cell see Figure 1 4 uses pre stressed alumina inserts to achieve pressures of up to 25 kbar The sample sizes are of the order of 4 mm in diameter and 10 mm long It is not possible to pressurise in situ and it takes several hours to cool the whole cell once it is on the instrument If experiments at pressure are intended then the equipment must be requested on the proposal form It is not available on demand TOSCA User Guide 10 66 Figure 1 4 A McWhan cell for pressure experiments up to 25 kbar 2 SAMPLE HANDLING This section describes how to prepare a sample load it into TOSCA and what to do if a centrestick g
42. it is being recorded Type qra This will result in an analysed spectrum that is not saved The output of QR4 is placed in workspace w5 The back scattering detectors are in w7 the forward in w9 and the sum in w5 Note that workspaces w1 w9 are overwritten during the analysis FR4 This is the main TOSCA data analysis program It is normally only used if data outside the usual range 2 500 meV 16 4000 cm is required or if saved SAV or co added files are to be analysed or when the batch file does not run or when the ANA file has been corrupted and the data has to be re analysed For co adding sequential runs there is a version of FR4 called SR4 see next topic Note that the RAW file is unchanged by FR4 in any of its manifestations The use of a fixed final energy on TOSCA means that each energy w is associated with a unique value of momentum transfer Q A second consequence is that Q is only weakly dependent on the scattering angle thus for the small angles subtended by the detector banks there is no variation in Q across the detector bank This means that the analysis of the raw time of flight data on TOSCA is straightforward In essence it consists of normalising each detector spectrum to the incident monitor spectrum conversion to energy transfer in meV and summing the detectors to give a single spectrum This process is sufficiently routine that it is carried out automatically by a batch file each time a ru
43. itio methods have proven to be very successful The programme aCLIMAX uses the atomic displacements generated by ab initio packages such as GAUSSIAN98 and DMOLS3 to generate the INS spectrum See Further Reading at the end of this section for more details on CLIMAX and aCLIMAX A consequence of the indirect geometry is that for energy transfers gt 100 cm the momentum transfer vector is essentially parallel to the incident beam The significance is that for an INS transition to be observable there must be a component of motion parallel to the momentum transfer vector This means that with oriented samples such as single crystals or aligned polymers measurements directly analogous to optical polarisation experiments carried out In addition to the inelastic detectors there are also two He filled detector tubes either side of the incident beam scattering angle 179 These are for elastically scattered neutrons and enable modest resolution A d d 3 x 10 diffraction patterns to be recorded simultaneously with the inelastic spectrum It is planned to install two further banks of diffraction detectors at 45 and 135 The purpose of the detectors is to provide a check on the crystal phase of the material and to monitor phase changes as an experimental variable is changed e g temperature and pressure There is also a low efficiency scintillation detector the monitor in the main beam just before the cryostat vacuum tank This measures the in
44. its cradle right and its controller bottom panel in electronics rack on the left The samplechanger can be loaded with sachets or liquid cells in any combination Sachets are mounted on an aluminium frame and held on with aluminium sticky tape The sachet must be held within the frame it should not protrude above it and the sticky tape should not be touch the chains The right hand side of Figure 2 4 shows a correctly mounted sachet To mount a liquid cell it may be necessary to remove an aluminium frame In either case note the six digit number on the clamping plate TOSCA User Guide 16 66 Figure 2 4 Loading samples on the 24 position samplechanger Left empty aluminium frame for a sachet note the six digit number at the top of the clamping plate Right sachet mounted on a frame A liquid cell is mounted at the position below it To move to a vacant position on the samplechanger use the handset attached to the controller in the electronics rack see Figure 2 5 There are four buttons on the handset forward is the second from the top back is the bottom button the first and third buttons are not used press and hold for either direction There is a green status light to the right of the digital display on the control rack the samplechanger will only move when this illuminated When the sample is in the correct position movement stops and the red sample in lock light is illuminated there are also two red lights on the samplec
45. lete path CONVERT This program coverts the x axis scale from meV to wavenumbers Type COon lt you will be prompted for the workspace w to be converted and then for the output workspace This can be the same or different to the input one STRETCH This program is similar to CONVERT but the x axis multiplicative factor is provided by the user This is useful for going from e g meV to THz cm to meV and for scaling by 1 V2 to simulate the expected spectrum for a deuterated sample from that of the protonated one Type gt Str you will be prompted for the workspace w to be converted then for the output workspace and then for the scaling factor this can be any real number or GAUS This gives access to a program that performs a least squares fit of a sum of Gaussian lineshapes to the experimental data Type Qaus For more information see the FRILLS manual TOSCA User Guide 49 66 SMOOTH This creates a smoothed spectrum using the Savitsky Golay method This programme overwrites the input workspace so it is sensible to copy the data to another workspace first To obtain the best results it is usually necessary to have several attempts The user is prompted for the workspace number in this case enter the number not w i e 12 not w12 The smoothing is then asked for generally 1 10 is optimal The order of the polynomial is then requested 0 2 4 The severity of the smoothing is 0
46. memoire to help you run your experiment and analyse your data It is not intended as a substitute for training For new users and those who are not regular users it is essential that you are properly trained in the use of the instrument by your local contact or the instrument scientist More detailed information on some aspects is available from other reports such as the sample environment equipment FRILLS a fit to a sum of Gaussian peaks and on programs such as GENIE Copies of these manuals can be obtained from your local contact although copies are kept in the instrument cabin A PUNCH manual can be found in the cabin and contains information on the Instrument Control Program ICP and sample environment controls via CAMAC This manual is specific for current version of TOSCA a pdf file is also available for download TOSCA User Guide 2 66 TOSCA Team TOSCA left to right Timmy Ramirez Cuesta Stewart Parker Instrument Scientists and John Tomkinson Group Leader Molecular Spectroscopy Group 1 TOSCA 1 1 Description of the instrument and basic INS theory TOSCA is an inelastic neutron scattering INS spectrometer optimised for vibrational spectroscopy TOSCA has replaced the previous spectrometers TFXA and TOSCA 1 however it retains the advantages of the earlier instruments ease of operation and reliability but simultaneously offers improved sensitivity and resolution TOSCA is a collaborative project between the Co
47. n waitfor 1000 uamps waitfor1000 end end run So io ee sets temper wait 40 min wait 00 40 00 temperatur stabilisation change title Sample at 80K Ba begin begins run waitfor 1000 uamps spaces are end exit Command files are created using the VMS editor and end with the extension com TOSCA User Guide 34 66 They are run from the TOSCA Control window using lt filename gt To interrupt a command file type Control Y Note that you are unable to use the window when a com file is running Note The two commands WAIT and WAITFOR are different and confusion over their use is one of the main causes of command file failures WAIT This is a VMS command that waits for a specified time The time must be given in the hrs mm secs format used by the VMS operating system e g WAIT 01 30 00 will wait for one hour 30 minutes before executing the next command WAITFOR This is an instrument control command and can be used to wait for certain amount of data to be collected The most common usage of the command is to wait for a certain number of microamps in this case the suffix uamps must be given after the number e g waitfor 1000 uamps will wait for 1000 microamps of beam current before executing the next command If ISIS goes off then it will sit and wait Note that the format is rigid there must be a space between the number and uamps A common requirement is to wait until the sample reach
48. n is ended and uses the raw time of flight data file RAW to generate the files TRSLxxx ANA TRSLFOxxx ANA and TRSLBAxxx ANA in the directory TOSCA DISKO TOSCA USER a few minutes later To run FR4 type fr4 The program asks for a number of inputs In the order in which they are required these are File extension 1 for RAW original data 2 for SAV files saved during a run TOSCA User Guide 45 66 3 for SUM co added data files Run number Energy binning choice and a value 1 for constant AE E 2 for constant AE The raw time of flight data is collected in bins of equal width thus as the energy transfer increases there are fewer time bins in a given energy width For most cases AE E is the better choice since it better matches the resolution function of the instrument and ensures that there are sufficient data points at each energy to correctly define the resolution AE is not the resolution it is the width in energy of a time bin The required value can be calculated from AE E V 0 0002 Emax where Emax is the highest energy in meV required in the spectrum For the standard range 2 500 meV a value of 0 005 is appropriate The energy range to analyse This is usually 3 5 500 meV 30 4000 cm Care is needed since there is an interplay between the type and size of the energy binning and the energy range Note that if the highest energy is too large or the value given for AE E is too small then
49. nalysis of Molecular Vibrations Using INS Nuclear Instruments and Methods in Physics Research 354 1995 53 58 An excellent overview of how to analyse INS data using normal coordinate analysis J Tomkinson Neutron Molecular Spectroscopy in Recent Experimental and Computational Advances in Molecular Spectroscopy R Fausto ed Kluwer 1993 pp229 249 Briefly describes the theory of INS and references to in depth treatments and some applications aCLIMAX is available from http www isis rl ac uk molecularspectroscopy It is described in D J Champion J Tomkinson and G J Kearley a CLIMAX a new INS analysis tool Appl Phys A 74 Suppl 2002 S1302 S1304 and A J Ramirez Cuesta TOSCA User Guide 8 66 aCLIMAX 4 0 The new version of the software for analysing and interpreting INS spectra Computer Physics Communications in press 2003 B S Hudson Inelastic neutron scattering a tool in molecular vibrational spectroscopy and a test of ab initio methods J Phys Chem A 105 2001 3949 3960 A demonstration of the power of the combination of ab initio calculations and INS spectroscopy 1 2 Sample Environment on TOSCA The beam size at the sample position is 40 mm high by 40 mm wide It is clearly advantageous to fill as much of the beam as possible For the best resolution the sample should be 1 mm thick however samples up to 4 mm thick are usable Solid samples are usually just wrapped in aluminium foil an
50. ne 3 where mis the mass of the neutron and vis its velocity Rearranging 3 gives 2E TES i 4 and since travel time distance velocity 5 It follows that the time of arrival at the detector T is the sum of the time from the moderator to the sample t and the time around the analyser t thus Tat ree 4 Yi Ve 2E m 6 Now since the final energy Es the distance round the analyser system and the length of the flight path from the moderator to the sample L are all known it follows that the time of arrival at the detector uniquely defines the incident energy Fj and hence the energy transfer at the sample Erans Thus it is a simple matter to convert from time of flight to energy The result is a spectrometer with no moving parts than can record spectra from 0 to 8000 cm although the best results are usually obtained below 2000 cm The resolution of the spectrometer is determined by a number of factors but for practical purposes can be taken to be 1 25 of the energy transfer The intensity of the th molecular vibrational transition is proportional to I QU expl QUe 7 Since neutrons have a mass approximately equal to that of the hydrogen atom an inelastic collision results in a significant transfer of momentum Q A as well as TOSCA User Guide 6 66 energy to the molecule On TOSCA the design is such that there is only one value of Q for each energy Q ETans 16 Other ins
51. nscrew bolts retaining blanking plate the pressure falls to 0 17 Remove the blanking plate and push the centrestick down into the cryostat RAPIDITY is needed but CARE must be used Bent centresticks are expensive to replace 18 Secure centrestick lid with bolts 19 Switch on the cryostat pump switch on right hand side of pump 20 Open valves 2 and 3 vacuum gauge begins to register 21 WAIT until the pressure drops to 25 millibar on the gauge on top of the CCR 22 Close the blue valve on the CCR and valves 2 and 3 and switch off the pump TOSCA User Guide 25 66 23 Reconnect the thermometer cable to centrestick 24 Check which sample is oriented correctly usually perpendicularly with respect to the neutron beam 25 Close the interlocked door do steps 4 8 in reverse 26 Open the shutter and start collecting data see section 4 Controlling the instrument 2 6 Removal from centrestick This work should be done with the sample centrestick being on the TOSCA centrestick stand on the work bench on the mezzanine floor 27 Turn the hot air blower on and warm the sample 28 Release the sample sachet from the cadmium lantern using long nose pliers to remove the retaining wire or aluminium tape Remember that cadmium metal strongly activates in the neutron beam 29 Remove the sample using tweezers or if you must gloved hands NEVER HANDLE ACTIVE SAMPLES WITH BARE HANDS TOSCA User Guide 26 66
52. nsiglio Nationale Recherche CNR of Italy the Department of Physics at the University of Kent at Canterbury UK and ISIS For a detailed list of the participants see the TOSCA website http www isis rl ac uk molecularspectroscopy tosca and the CNR website http www ifac cnr it tosca tosca main htm TOSCA was installed in two phases phase 1 was completed in May 1998 and consisted of the backscattering spectrometer at 12 m phase 2 added detectors in forward scattering and moved the spectrometer to 17 0 m This was completed in September 2000 The move to 17 m from 12 m has resulted in a large improvement in resolution TOSCA User Guide 3 66 TOSCA Detectors Forward scattering analysers Backscattering analysers Figure 1 1 TOSCA showing the detector analyser modules TOSCA is an indirect geometry time of flight spectrometer at the ISIS pulsed spallation neutron source at the Rutherford Appleton Laboratory A section through one of the analyser modules is shown in Figure 1 2 It is optimal in the energy range 0 4000 cm 0 500 meV with the best results below 2 000 cm 250 meV To suppress the amp gamma flash and fast neutron background a Nimonic chopper is installed at 9 5 m This has a tailcutter a sheet of B4C on the leading edge to remove low energy neutrons that would otherwise result in frame overlap TOSCA User Guide 4 66 Closed cycle refrigerator Detectors eee AADOINA encagceaganaand
53. nterface When the control system for the samplechanger was designed it was intended that it would be run exclusively from the Ray of Light interface a GUI on top of the LabView control programme Ultimately this will happen when TOSCA is run from a PC rather than VMS In practice it is better to run the samplechanger from VMS and use Ray of Light simply as a connection in the chain However for the VMS commands to work Ray of Light must be operating correctly When the main supply cable is detached from the samplechanger Ray of Light will often hang This is noticeable because the webcam view is not correct It is re started by pressing QUIT in the top left of the screen the programme will exit and automatically re start This takes a couple of minutes The samplechanger can be moved by using the buttons in the lower centre of the screen If you change the number of steps positions labelled Steps then reset it to 1 afterwards because VMS uses the value set on the screen In theory going forwards or backwards should work equally well Experience shows that going backwards is when the samplechanger is most likely to jam the only cure is to remove it from TOSCA warm it to room temperature and put it back in the instrument This can result in anything up to 12 hours lost time You have been warned TOSCA User Guide 39 66 The samplechanger is run from VMS at the command level where END BEGIN etc are done not in GENIE
54. of the screen are four buttons labelled one to four Each of these has its own screen associated with it and each screen can have as many windows as desired The convention that is used is TOSCA User Guide 29 66 Screen 1 is used for displaying the instrument status the Dashboara and controlling the instrument Screen 2 is used to display data using GENIE Screen 3 is for OPENGENIE Screen 4 is for the users e g to telnet to their home computer To create a window on the toolbar click on the icon for a terminal 4th from the left in Figure 3 1 a menu then pops up and click on the item labelled DECTERM This procedure is the same in any of the screens DECtemn 71 WINDOWSBW2 queue SYS gt I JOBSTART Job 2WINDOW ob 2WINDOWSBW2 queue SYS LSR17 Figure 3 1 Top the toolbar on the TOSCA terminal in the cabin bottom Screen 1 showing the Dashboard and the Control window TOSCA User Guide 30 66 oa TOSCA File Edit Commands Options Print status 4l T RUN 4818 4 Run User and z number title aser PE Teer FALS 0 00 am 5 anr gt _ Temperatt left total microamps Job ZWINDOWSEW2 queue 5Y entry 3631 completed ri ht Tosca g 0CPS OBSTART Job 2uiI queue POST LSR17 entry 3834 started on SYS LSR1 TOSCA gt Job 2WINDOWSBW2 queue SYS LSR17 entry 3894 completed ENE Figure 3 2 The Dashboard on the T
55. re sensitive samples except that the can is loaded in a glovebox 2 2 1 Preparing an aluminium sachet 1 Tear off a piece of foil 20 cm long and fold it over TOSCA User Guide 11 66 Se 2 1st Z fold on right hand side Y 3 Press Z fold flat using back of fingernail or plastic ruler i 4 From outer fold mark off sachet width this is normally 40 mm however for bulky samples this must be 50 mm 5 2nd Z fold on left hand side TOSCA User Guide 12 66 lt 2 Anes Ow fer 6 Press Z fold flat and cut away excess foil from the sides 7 Open the sachet with a pencil or spatula 8 Fill the sachet Note that it is often valuable to know exactly how much sample is in the beam so weighing the sachet before and after filling it is good practice ey ward Aa PREP aa 1H Ct Canad 9 Tamp the sample gently to the bare of the sachet Close off the sachet immediately above the sample using finger and thumb 10 At a height of 40mm from the base of the sachet fold a few times to seal 11 The sample should be evenly distributed throughout the sachet using a cylindrical bottle like a rolling pin Hints 1 Using a blunt pencil the sachet can be impressed with a name 2 If you have produced a sample that is too thin DO NOT start afresh simply make TOSCA User Guide 13 66 another and run both 3 If you puncture a sachet enclose this sachet in some Al foil which can be
56. red by Pt resistance thermometers The output of these is displayed in the bank of ten readouts in the section of the TOSCA cabin that holds the electronics racks see Figure 5 3 Each of the filters should be below 50K there is an alarm signal the red LED on the panel if the temperature exceeds this Again it is a useful precaution to check the temperatures of the Be filters once or twice a day If a filter is above 50K check that all the compressors are operating and then inform your local contact TOSCA User Guide 56 66 Figure 5 2 The compressors for the Be filters outside R55 TOSCA User Guide 57 66 Be filter temperat readouts Figure 5 3 a The section of the TOSCA cabin that holds the electronics racks showing the key elements b The Be filter temperature readouts and the chopper controls Note 50 in the TOSCA User Guide 58 66 middle of it 5 2 The top loading CCR The major piece of sample environment equipment available on TOSCA is the top loading CCR This is designed to be compatible with the standard ISIS centresticks thus the distance from the underside of the flange to the beam centre is 1165 mm and the bore is 100 mm The advantage of this system is that the sample can be changed without having to warm the cryostat to room temperature It is cooled by three CCR heads one single stage compressor cools the outer thermal radiation shield to 40K and two two stage heads cool the inner vacuum v
57. ron beam There are two sets of interlock keys The Master M key which is to be found on the front of the Green box and is labelled with a red tag The remainder are S keys which are located in the Blue box see Figure 2 7 There are two shutter control boxes one in the cabin and one on the services panel behind the cloche Note You only have control of the shutter if the Master key is in the Green box If you try to operate the shutter whilst the interlocks are not complete you will trip off ISIS Beam off button i he l ox Green box Figure 2 6 TOSCA services panel showing the Green bottom left and Blue centre left interlock boxes and the shutter control bottom middle The Master key is only released when the neutron shutter is closed Conversely the shutter can only be opened if the key is in place in the Green box TOSCA User Guide 19 66 The S keys give access to the sample enclosure and other controlled areas They can be released by placing the Master key in the bottom right hand slot of the Blue box This is normally the only vacant slot 1 END the current run the Dashboard changes to SETUP and write the time Run No and total number of microamps used into the Instrument Diary 2 Close the shutter to the beam green button marked CLOSE on the Neutron Beam Shutter Control Panel located on the services panel by TOSCA Figure 2 7 and in the cabin Figure 2 8 The shutter takes
58. scattering and forward scattering detectors whether the units are meV or cm 1 and the position of the same peak in the forward and backscattering spectra DERIVATIVE This calculates the derivative spectrum for a chosen workspace Type der Then follow the on screen instructions Note that it uses additional workspaces for intermediate steps so data may be overwritten 4 1 8 Assigning files It is occasionally necessary to look at the raw time of flight data from the individual detector tubes To do this type ass dae for the current run or aSS XXXX where xxxx is the run number for a previous run To display an individual spectrum d s where is the tube number Tubes 1 140 are the inelastic detectors tube 141 is the monitor and tubes 146 149 are the diffraction detectors To manipulate the data it must be put into a workspace For example to put spectrum 3 into workspace 1 type wl ssc TOSCA User Guide 52 66 Then display as described earlier To look at more than one tube use the multiplot command see GENIE manual mu sl gt s56 1000 20000 lt This will display the data in detectors 1 to 56 between 1000 and 20000 ms 4 2 OPENGENIE OPENGENIE is the successor to GENIE It is more flexible e g unlimited number of workspaces able to handle two dimensional data sets command line recall by use of up arrow etc A HELP file is available on line on the web at http
59. ser tsumslxxx ana toscaSdisk0 tosca user tsumslbaxxx ana toscaSdisk0 tosca user tsmslfoxxx ana where xxxx is the run number of the first of the consecutive files TEMP_PLOT and TEMP_PLOT_CURRENT These programs plot the temperature vs time for an old run and the current run respectively Type tp or tpc Both programs are run in the same way and are very similar The only difference is that after starting tp you are asked for the run number and then asked to give the start date and time whereas tpc immediately asks for the start date and time The simplest method is to accept the defaults which is just a return If you want to input values then these must be in the format xxX mon year hr min sec e g 12 jul 1995 09 45 00 TOSCA User Guide 47 66 The space between the year and the time is essential You are then asked for the finish time in the same format When prompted Give Se block name Type temp for the sample temperature history or temp1 for the cryostat temperature history You are then prompted for the temperature units K or C and for which log column the default is 3 and this should be used The program then extracts the relevant data from the temperature log This may take several minutes so be patient Eventually it comes up with the message Ok Toggle mode to point plotting and d l wl Toggle mode switches between using the edge of data bins and the centres Unless there are
60. st relying on the sum file Fortunately the shift in positions is symmetric about the true position This programme uses the difference in position of a band between the forward and backscattering spectra to generate corrected spectra Before running the programme use the cursor to determine the position of the same sharp peak in the forward and backscattering spectra The sequence of commands is user input in bold gt gt comp gt gt TOSCASDISKO TOSCA COMMAND COMP COM gt gt gt gt Compensating the back scattering and gt gt forward scattering det banks gt gt gt gt gt gt ENTER INPUT WORKSPACE NUMBER BA 1 gt gt BA TOSCA User Guide 51 66 workspace to be compensated 1 gt gt ENTER OUTPUT WORKSPACE NUMBER BA 5 gt gt Compensated BA workspace 5 gt gt ENTER INPUT WORKSPACE NUMBER FO 2 gt gt FO workspace to be compensated 2 gt gt ENTER OUTPUT WORKSPACE NUMBER FO 6 gt gt Compensated FO workspace 6 gt gt In meV 1 or cm 1 0 O gt gt Energy units of the following w points gt gt BA w axis point 1082 gt gt BA w axis point gt gt FO w axis point 1090 gt gt FO w axis point In this example the spectra to be corrected are in w1 and w2 and the corrected spectra are put in w5 and w6 Any workspaces may be used The user is prompted for the input and output workspaces number only not w for the back
61. truments at the ISIS Facility and the ILL allow both the energy and the momentum transfer to be varied but they constitute a different story U is the amplitude of vibration of the atoms undergoing the particular mode The exponential term in equation 7 is known as the Debye Waller factor U7ota is the mean square displacement of the molecule and its magnitude is in part determined by the thermal motion of the molecule This can be reduced by cooling the sample and so spectra are typically recorded below 50K o is the inelastic neutron scattering cross section of all the atoms involved in the mode The scattering cross sections are a characteristic of each element and do not depend on the chemical environment The cross section for hydrogen is 80 barns while that for virtually all other elements is less than 5 barns This means that modes that involve significant hydrogen displacement will dominate the spectrum This dependence on the cross section is why the INS spectrum is so different from infrared and Raman spectroscopies There the intensity derives from changes in the electronic properties of the molecule that occur as the vibration is executed the dipole moment and the polarisability for infrared and Raman spectroscopy respectively Analysis of INS spectra can be carried out in many ways For molecular systems normal coordinate analysis using the Wilson GF matrix method as implemented in CLIMAX has long been used More recently ab in
62. u can type p w Where is the number of the workspace to be added to the current graphics window This is useful for comparing accurately two or more spectra A useful device is to display the data using the d command in a histogram format and then to overlay the error bars by using p e 4 1 4 Binning and rebinning The bin size represents the number of adjacent points averaged for each data point So a binning of 1 i e no binning has a high accuracy but may also have high noise levels A numerically larger binning will give reduced noise but the resolution will be degraded thus binning acts as a crude type of smoothing The advantage is that the data in the workspace is not permanently changed To alter the binning type a b x TOSCA User Guide 42 66 Where x integer only represents the binning number usually between 1 and 10 The GENIE command rebin allows different portions of the workspace to be averaged to different extents unlike binning which operates on the whole workspace but permanently changes the data in the workspace Thus the best method is to copy the data to another workspace by e g w w2 and then to experiment on the second workspace There are two forms to the command reb w2 16 2 4000 reb w2 16 02 200 005 4000 In form 1 with brackets the value inside the brackets is in x units So for a spectrum in wavenumbers the first command will rebin the dat

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