Pixie-4 User`s Manual
Contents
1.2. 64 If the PLX is missing it indicates driver version 4 1 is used A picture of the driver information reported by Windows is shown below Ax General Driver Details Resources r e PL Custom OEM PCI 9054 Board 32 Driver Provider PLX Technology Inc Driver Date 6 1 2011 Driver Version 6 5 0 0 Digital Signer Not digitally signed Driver Details To view details about the driver files Update Driver To update the driver software for this device bekoi a ary gea Disable Disables the selected device Uninstall To uninstall the driver Advanced 5 When starting the Pixie Viewer IGOR reports compile error For IGOR to start up properly a number of driver files have to be in the correct 18 Pixie 500 User s Manual V2 50 O XIA 2012 All rights reserved locations In particular the file pixie xop has to be located in the Igor Extensions folder usually C Program Files Wavemetrics Igor Pro Igor Extensions in a default installation and the file PlxApi631 dll has to be in C Windows System32 When starting up modules in the Pixie Viewer downloads are not successful This can have a number of reasons Verify that The files and paths point to valid locations run the UseHomePaths macro The slot numbers entered in the Startup panel match the location of the modules The correct drivers are used version 6 4 2 and modules are recognized in Wind
3. H m e Batteries Computer a Disk drives E Display adapters es DVD CD ROM drives QS Human Interface Devices Ca IDE ATA ATAPI controllers gt Keyboards R Mice and other pointing devices 5 Modems amp Monitors amp Network adapters Y NIMXI Devices gt Other devices No PLX Custom OEM PCI 9054 Board 32 Processors a Sound video and game controllers lt gt Storage controllers q amp System devices y Universal Serial Bus controllers e j AE 17 Pixie 500 User s Manual V2 50 XIA 2012 All rights reserved 3 Windows can not use drivers due to problem in digital signing This problem seems most common in Windows 7 The PLX drivers currently only inofficially support Windows 7 While this is being addressed a workaround solution is to install the complete PLX software development kit SDK which seems to install the PLX drivers in a way acceptable to Windows 7 The SDK is available for free from PLX http www plxtech com but registration is required 4 Drivers are installed but module does not boot The Pixie 500 modules require driver version 6 5 0 provided by XIA not the earlier versions 6 3 1 5 2 4 1 or 4 4 Modules should be listed in Window s device manager as PLX Custom OEM PCI 9054 Board 32 or
4. oooooccnonccconcncnonccononcnonncnonocnononnoncnconcnnonnnnnos 15 S Troubleshooting od A A At Salen 16 8 1 Startup Problems cias ia ida ds tines 16 8 2 Acquisition Problema liada 20 A NR 22 AIM A A A E a E a A TRO 22 9 2 PXI backplane pin fUNCtIONS cc eecccesceeseeeeseeeeseeeeceeesceceeeeeeeeeeneeseaecenseeeseeeeeeeeeeiaeeesenees 23 9 3 Control and Status Register Bits ccecsccccsscesseceeseeeeseeceseeeseeeeeseecesaeesseceeesenaeeeessenaeeeeeenes 24 2 Pixie 500 User s Manual V2 50 XIA 2012 All rights reserved 1 Overview This manual describes the DGF Pixie 500 a 4 channel all digital waveform acquisition and spectrometer card based on the CompactPCI PXI standard The Pixie 500 currently comes in a 12 bit 500 MHz version and a 14 bit 400 MHz version Since for both versions most of the design and operating principles are the same as for the DGF Pixie 4 this manual focuses on the differences to the Pixie 500 Users are referred to the Pixie 4 User manual for more detailed descriptions Significant difference for the Pixie 500 are highlighted 1 1 Features of the Pixie 500 e Designed for high precision y ray spectroscopy with fast radiation detectors e g scintillator PMT combinations Nal LaBr etc and many others e 12 bit 500 MHz or 14bit 400 MHz ADC resulting in energy resolutions close to HPGe capabilities e Simultaneous amplitude measurement and pulse shape analysis for each channel e Programma
5. pulses from a pulser In the Energy tab of the Parameter Setup panel input an estimated preamplifier exponential RC decay time for Tau and then click on Auto Find Tau to determine the actual Tau value for all channels of the current module You can also enter a known good Tau value directly in the Tau control field or use the controls in the OsciLoscorE to manually fit Tau for a pulse Save the modified parameter settings to file To do so click on the Save button at the bottom of the Parameter Setup panel to open a save file dialog Create a new file name to avoid overwriting the default settings file Save the Igor experiment using File gt Save Experiment As from the top menu This saves the current state of the interface with all open panels and the settings for file paths and slot numbers the settings independent of module parameters Click on the Run Control tab set Run Type to 0x301 MCA Mode Poll time to 1 second and Run time to 30 seconds or so then click on the Start Run button A spinning wheel will appear occasionally in the lower left corner of the screen as long as the system is waiting for the run to finish If you click the Update button in the Maw panel the count rates displayed in the Results group are updated After the run is complete select MCA Spectrum from the Open Panels popup menu in the Results group of the Main panel The MCA spectrum graph shows the MCA histograms for all four channels You can desel
6. AMETER Setup panel Measure the decay time several times and settle on the average value Fine tuning of T can be achieved by exploring small variations around the fit value 2 3 This is best done at high count rates as the effect on the resolution is more pronounced The value of t found through this way is also valid for low count rates Manually enter T take a short run and note the value of 7 that gives the best resolution Pixie users can also use the fit routines in the OsciLLoscoPE to manually find the decay time through exponentially fitting the untriggered input signals Another tool is the Optimize 11 Pixie 500 User s Manual V2 50 XIA 2012 All rights reserved routine in the Energy tab of the PARAMETER Setup panel Similar to the routine for finding the optimal energy filter times this routine can be used to automatically scan a range of decay times and find the optimal one Please refer to the Online Help documentation for more details A further option is to create a file series where Tis modified for each file in the series See section 3 6 of the Pixie 4 user manual for more details 12 Pixie 500 User s Manual V2 50 XIA 2012 All rights reserved 4 Data Runs and Data Structures 4 1 Run Types There are two major run types MCA runs and List mode runs MCA runs only collect spectra List mode runs acquire data on an event by event basis but also collect spectra List mode runs come in several variants s
7. User s Manual V2 50 XIA 2012 All rights reserved 9 Appendix A This section contains hardware related information 9 1 Jumpers Table 10 1 Analog conditioning selection jumpers on Pixie 500 modules x 1 4 for channel 0 3 Jumpers are marked with solid red 50Q and dashed blue attenuation arrows reference 3 pin jumper pins are labeled 1 middle 1 8 Connect lt 4 middle with 1 8 if you require attenuation JPx02 50 Set for input impedance of 50Q If not set input impedance is A _ 8 5ka 21 Pixie 500 User s Manual V2 50 XIA 2012 All rights reserved Table 10 2 On board jumper settings for the clock distribution on Pixie 500 modules Clock mode JP1 and JP2 JP3 PCB Label Single Module Connect pins 2 and 3 of JP2 LOC to IN Daisy Chained Connect pins 2 and 3 of JP2 not set LOC to IN Clock Master Daisy Chained Not set set Left Clock Repeater Master Connect pinl JP1 to pin 1 JP2 OUT to BUS Slave PXI clock Clock Master for Connect pin2 JP1 to pin 2 JP2 not set PXI to IN PXI clock Connect pin3 JP1 to pin 3 JP2 LOC to BP Revision C only 9 2 PXI backplane pin functions Table 10 3 Pins of the J2 backplane connector defined in the PXI standard used by the Pixie 500 Pins not listed are not connected except for pull ups to 5V recommended by the PXI standard J2 pin PXI pin Connection Type Pixie pin function number name LBR4 Right neighbor r
8. User s Manual Digital Gamma Finder DGF Pixie 500 Version 2 50 June 2012 XIA LLC 31057 Genstar Road Hayward CA 94544 USA Phone 510 401 5760 Fax 510 401 5761 http www xia com Disclaimer Information furnished by XIA is believed to be accurate and reliable However XIA assumes no responsibility for its use or for any infringement of patents or other rights of third parties which may result from its use No license is granted by implication or otherwise under the patent rights of XIA XIA reserves the right to change the DGF product its documentation and the supporting software without prior notice Table of Contents VOW Wii Aa 3 1 Features Ot the PIE OO A A anno 3 AS A RTS 3 1 3 Important Notes on Power CONSUMPtiOM occoococonocconnnconnnoonnnonononnnnoconnnonnnnnnnnrnnn non nnnnnnn nn rrnnnannnnnos 4 A O RT 4 DA EA A O 4 2 2 Getting Started iii a ts a a 7 3 Navigating the Pixie VI Wei ladito EE EN 10 E O oaseais teascraaye 10 3 2 0ptimizing Para Met AAA de ai 10 4 Data Runs and Data StrUCTULES oooocononocnonnnoonnnnonccnononcnncn cono ncno nono n nc non nrnan rr nan nrnan rn nan rn ran nr ran rn rnannnnnnno 13 4 l Rutt Types nit A A A E anions 13 4 2 Output Data ia A A ni n 13 43 Input Output A E E Eina EEEE E aaa 13 Hardware Descriptloniv cisccsi exetanteteeesteeds ti odes E EE A A A A ARA sd 15 6 Theory of Operation tad E A ta dt ee 15 7 Operating Multiple Pixie 500 Modules Synchronously
9. ble gain high low and input offset e Programmable pileup inspection criteria include trigger filter parameters threshold and rejection criteria e Triggered synchronous waveform acquisition across channels modules and crates e Supports 32 bit 33 MHz PCI data transfers gt 100 Mbytes second 1 2 Specifications Front Panel I O Signal Input 4x 4 analog inputs Selectable input impedance 50Q and 8 5kQ 5V pulsed 2V DC Selectable input attenuation 1 8 8 and 1 1 for either impedance setting Logic Input Output General Purpose I O connected to programmable logic Currently can be either used as input for global backplane signals Veto or Status or as an input for module specific logic level reported in the data stream or as an external trigger Logic Output General Purpose output from Digital Signal Processor Function to be determined Backplane I O Distributed 37 5 MHz clock on PXI backplane Triggers Two wired or trigger buses on PXI backplane One for synchronous ee waveform acquisition one for event triggers Global logic level from backplane reported for each event Global logic level from backplane used for coincidence tests Synch Wired or SYNC signal distributed through PXI backplane to synchronize timers and run start stop to 50ns Global logic level to suppress event triggering 3 Pixie 500 User s Manual V2 50 XIA 2012 All rights reserved Channel Gate Individual GATE to suppress event trig
10. e most essential settings For an initial setup go through the following steps MM Parameter Setup Trigger Waveform Gate Coincidence Advanced Run Control Auto Find Tau A A b LA A A v A A w v lt gt gt sent sunean Start System Oscilloscope S Save Ji Extract Figure 2 2 The Parameter Setup Panel Energy tab shown 1 If not already visible open the ParameTER Setup panel by selecting Parameter Setup from the Open Panel popup menu in the Maw panel 2 At the bottom of the Parameter Setup panel click on the Oscilloscope button This opens a graph that shows the untriggered signal input In the OsciLoscore panel click Refresh to update the display The pulses should fall in the tt If no pulses are visible or if they are cut off at the upper or lower range of the display click Adjust Offsets to automatically set the DC offset If the pulse amplitude is too large to fall in the display range decrease the Gain If the pulses are negative toggle the Invert checkbox 8 Pixie 500 User s Manual V2 50 XIA 2012 All rights reserved e Oscilloscope Channel dT us Offset Gain VIV Offset Vv Invert Buttons Tau Rates IMLO 0 053 10 1 314 0 118 M i 0 053 10 1 314 0 118 iil 2 0 053 10 1 314 0 118 MIES 0 053 10 1 314 0 118 Adjust Offsets Close n a 3 Capture KAK 14 bit ADC Units Figure 2 3 Osc LLoscore panel with typical
11. ect other channels while working on only one channel After defining a range in the spectrum with the cursors and setting the fit option to fit peaks between cursors you can apply a Gauss fit to the spectrum by selecting the channels to be fit in the Fit popup menu You can alternatively enter the fit limits using the Min and Max fields in the table or by specifying a Range around the tallest peak or the peak with the highest energy To scale the spectrum in keV enter the appropriate ratio in the field keV bin 9 Pixie 500 User s Manual V2 50 XIA 2012 All rights reserved At this stage you may not be able to get a spectrum with good energy resolutions You may need to adjust some settings such as energy filter rise time and flat top as described in section 3 2 3 Navigating the Pixie Viewer 3 1 Overview The Pixie Viewer consists of a number of graphs and control panels linked together by the Maw control panel The Viewer comes up in exactly the same state as it was when last saved to file using File gt Save Experiment This preserves settings such as the file paths and the slot numbers entered in the Start Up panel However the Pixie module itself loses all programming when it is switched off When the Pixie module is switched on again all programmable components need code and configuration files to be downloaded to the module The Pixie Viewer is described in more detail in the Pixie 4 User manual section 3 Detailed information
12. ected by the installation program or to a custom folder This folder will contain the IGOR control program Pixie500 pxp or Pixie400 pxp online help files and 8 subfolders Configuration Doc Drivers DSP Firmware MCA PixieClib and PulseShape Make sure you keep this folder organization intact as the IGOR program and future updates rely on this Feel free however to add folders and subfolders at your convenience 6 Pixie 500 User s Manual V2 50 XIA 2012 All rights reserved 2 2 Getting Started To start the Pixie Viewer double click on the file Pixie500 pxp or Pixie400 pxp in the installation folder After IGOR loaded the Pixie Viewer the Start Up panel should be prominently displayed in the middle of the desktop In the panel first select the chassis type and number of Pixie 500 modules in the system Then specify the slot number in which each module resides ME Pixie4 NI 14 or 18 slot chassis 3U Open Panels Start System ZAN 11 Figure 2 1 The Pixie 500 Starr Ur panel above and Maw Panel right Click on the Start Up System button to initialize the modules This will download DSP code and FPGA configuration to the modules as well as the module parameters Due F tl H A it will take 5s per module to compl see messages similar to Module 0 in slot 5 started up successfully in the IGOR history window the Pixie 500 modules have been initialized successfully Otherwise re
13. ed users with embedded host computer skip to step 4 1 If you have a remote controller first install the driver software for the controller itself Otherwise skip to step 4 Unless directed otherwise by the manufacturer of the controller this can be done with or without the controller and Pixie 500 modules installed in the host computer and or chassis If the modules are installed ignore attempts by Windows to install drivers until step 7 NI controllers come with a multi CD package called Device Driver Reference CD For simplicity it is recommended to install the software on these CDs in the default configuration 2 Unless already installed power down the host computer install the controller in both the host computer and chassis and power up the system again chassis first 3 Windows will detect new hardware the controller and should find the drivers automatically Verify in Window s device manager that the controller is properly installed and has no resource conflicts 4 Install Igor Pro Install the Pixie 500 software provided by XIA see section 2 1 3 6 Unless already installed power down the host computer and install the Pixie 500 modules in the chassis Check the input jumper settings for the appropriate signal termination 50 Q or 5 kQ see section 9 1 for details Then power up the system again chassis first 7 Windows will detect new hardware the Pixie 500 modules and should find the drivers auto
14. eserved 3 3 3 3 TRIGO TRIG4 LBR5 Right neighbor LBRO Right neighbor AN see PEE LBL10 Left neighbor Fast Trigger output chained OR LBL10 Left neighbor Fast Trigger output chained OR 29 Pixie 500 User s Manual V2 50 O XIA 2012 All rights reserved AAA eee ee A PA A A 9 3 Control and Status Register Bits Table 10 4 Control and Status Register of the Pixie 500 System FPGA 0x0001 RunEna Set to 1 to start data acquisition or 0 to stop Automatically cleared when DSP de asserts Active to end run 0x0002 Unused Reserved for future use 0x0004 PClactive Set to reserve external memory I O for host 0x0008 Unused Reserved for future use 0x0010 DSPReset Write only Set to reset DSP processor to initiate program download 0x0020 SynchCtrl Read only If low module is busy with run initialization has filled its I O buffer with data or is finished with the run 0x0040 Unused Reserved for future use 0x0080 Unused Reserved for future use 0x0100 SynchFlag Read only Reserved for future use 0x0200 Live Read only If zero DSP is taking data 0x0400 Unused Reserved for future use 0x0800 Unused Reserved for future use 0x 1000 Unused Reserved for future use 0x2000 Active Read only If set there is a run in progress 0x4000 LAMState Read only If set LAM is set internally 0x8000 Unused Reserved for future use 23 Pixie 500 User s Manual V2 50 XIA 2012 All rights reserved
15. fer to the troubleshooting section for possible solutions If you want to try the software without a chassis or modules attached click on Offline Analysis After the system is initialized successfully you will see the Mam control panel that serves as a shortcut to the most common actions and from which all other panels are called Its controls are organized in three groups Setup Run Control and Results 3 In the following SmaLL Cars are used for panel names italic font is used for buttons and controls 7 Pixie 500 User s Manual V2 50 XIA 2012 All rights reserved In the Setup group the Start System button opens the Start Ur panel in case you need to reboot the modules The Open Panels popup menu leads to four panels where parameters and acquisition options are entered They are described in more detail in section 3 and in the online help To get started select Parameter Setup which will open or bring to front the PARAMETER Setup panel shown in Figure 2 2 For most of the actions the Pixie Viewer interacts with one Pixie module at a time The number of that module is displayed at the top of the Main panel and the top right of the Parameter Setup panel Proceed with the steps below to configure your system Note The More Less button next to the Help button on the bottom of the PARAMETER SETUP panel can be used to hide some controls This may be helpful to first time Pixie users who only want to focus on th
16. gering for each channel with use of PXI PDM not yet implemented Data Interface PCI 32 bit 33MHz Read Write memory readout rate to host over 100 Mbytes s Digital Controls Gain Analog switched gain of 1 0 or 2 9 igital gain adjustment of up to 10 in 15ppm steps Offset 2 5V to 2 5V in 65535 steps Shaping Digital trapezoidal filter Rise time and flat top set independently in small steps Trigger Digital trapezoidal trigger filter with adjustable threshold Rise time and flat top set independently Data Outputs Spectrum 1024 32768 channels 32 bit deep 4 2 billion counts bin Additional memory for sum spectrum for clover detectors Real time live time filter and gate dead time input and throughput counts Pulse height energy timestamps pulse shape analysis results waveform data and ancillary data like hit patterns 1 3 Important Notes on Power Consumption A Pixie 500 module consumes roughly 25W which eventually is turned into heat in the chassis Some elements of the board will get very hot for example the ADCs alone consume 2W each and will be too hot to touch The chassis therefore has to have sufficient cooling capacity to keep the operating temperature in a reasonable range It is strongly recommended to keep the chassis fan in the high setting if the chassis has such an option Some chassis may provide overall less power than required to operate a Pixie 500 module in each slot Please contac
17. given time depends on a the data per event b time required to record an event and c the data transfer rate 19 Pixie 500 User s Manual V2 50 XIA 2012 All rights reserved To reduce a run in compressed list mode run types 0x101 103 shorten the tracelength as much as possible can be zero in 0x101 103 remove the read always and good channel option for unused channels To reduce b reduce the coincidence window to the minimum possible if no pulse shape analysis is required in compressed list mode runs set the tracelength to zero do not require pulse shape analysis To increase c run in 32x buffer or 16 16 double buffer mode avoid frequent updates of run statistics and spectra set the polling time to a small value 0 1 0 01 verify the number of events buffer is set to the maxium 9 Bad energy resolution in MCA spectrum verify the decay time is set correctly increase energy filter rise time make the energy filter flat top approximately equal to the rise time of the pulse ensure the integrator is set to zero if integrator is set to 1 on purpose e g fast scintillator pulses make sure the energy filter flat top covers the entire pulse if integrator is set to 2 on purpose e g square pulses make sure the energy filter flat top covers the portion of the pulse that should be disregarded for the energy measurement e g the rising edge 20 Pixie 500
18. ks will appear at the low energy end of the spectrum If the threshold is too high especially at high count rates low energy events below the threshold can pass the pile up inspector and pile up with larger events This increases the measured energy and thus leads to exponential tails on the ideally Gaussian peaks in the spectrum Ideally the threshold should be set such that the noise peaks just disappear The settings of the trigger filter have only minor effect on the resolution However changing the trigger conditions might have some effect on certain undesirable peak shapes A longer trigger rise time allows the threshold to be lowered more since the noise is averaged over longer periods This can help to remove tails on the peaks A long trigger flat top will help to trigger better on slow rising pulses and thus result in a sharper cut off at the threshold in the spectrum 3 2 4 Decay Time The preamplifier decay time Tis used to correct the energy of a pulse sitting on the falling slope of a previous pulse The calculations assume a simple exponential decay with one decay constant A precise value of T is especially important at high count rates where pulses overlap more frequently If t is off the optimum peaks in the spectrum will broaden and if Tis very wrong the spectrum will be significantly blurred The first and usually sufficiently precise estimate of t can be obtained from the Auto Find routine in the Energy tab of the PAR
19. le Pixie 500 Modules Synchronously When many Pixie 500 modules are operating as a system it may be required to synchronize clocks and timers between them and to distribute triggers across modules It will also be necessary to ensure that runs are started and stopped synchronously in all modules All these signals are distributed through the PXI backplane and follow the same principles as in the Pixie 4 Please see the Pixie 4 user manual for a detailed description Significant differences in the Pixie 500 are 16 Pixie 500 User s Manual V2 50 XIA 2012 All rights reserved Trigger distribution across PXI bus boundaries is currently not implemented Gate signals for individual channels are currently ignored 8 Troubleshooting 8 1 Startup Problems 1 Computer does not boot when Pixie module is installed in chassis This is usually caused by an incorrect clock setting on the Pixie module The module needs to have a valid clock to respond to the computer s scanning of the PCI bus 2 Computer reports new hardware found needs driver files Whenever a Pixie module is installed in a slot of the chassis for the first time it is detected as new hardware even if Pixie modules have been installed in other slots previously Point Windows to the driver files provides with the software distribution After driver installation the module should appear in Window s Device Manager as in the picture below E File Action View Help
20. matically If not direct it to the drivers directory in the Pixie 500 software distribution installed in step 5 Verify in Window s device manager that the modules are properly installed as PLX Custom OEM PCI 9054 Boards 32 or 64 and have no resource conflicts Currently the driver must be version 6 5 0 In some systems scan for hardware changes in the Windows device manager may detect and install a remote chassis when the PC was booted first For information on using the older PLX drivers version 6 3 1 with Windows 2000 see the readme file in the Drivers folder of the software distribution 5 Pixie 500 User s Manual V2 50 XIA 2012 All rights reserved 2 1 3 Pixie User Interface The Pixie Viewer XIA s graphical user interface to set up and run the Pixie 500 modules is based on WaveMetrics IGOR Pro To run the Pixie Viewer you have to have IGOR Version 5 0 or higher installed on your computer By default IGOR Pro will be installed at C Program Files WaveMetricslIGOR Pro Folder The CD ROM with the Pixie 500 software distribution contains 1 an installation program Setup exe 2 the Pixie 500 software in the folder XIA P1ixie500 and its subfolders For the 400 MHz variant the folder is named Pixie400 The Pixie 500 software can be installed by running its installation program Follow the instructions shown on the screen to install the software to the default folder sel
21. on the individual controls can also be found in the Online Help for each panel 3 2 Optimizing Parameters Optimization of the Pixie 500 s run parameters for best resolution depends on the individual systems and usually requires some degree of experimentation The Pixie Viewer includes several diagnostic tools and settings options to assist the user as described below 3 2 1 Noise For a quick analysis of the electronic noise in the system you can view a Fourier transform of the incoming signal by selecting OscitLoscope gt FFT The graph shows the FFT of the untriggered input sigal of the OscitLoscope By adjusting the dT control in the OsciLLoscope and clicking the Refresh button you can investigate different frequency ranges For best results remove any source from the detector and only regard traces without actual events If you find sharp lines in the 10 kHz to 1 MHz region you may need to find the cause for this and remove it If you click on the Apply Filter button you can see the effect of the energy filter simulated on the noise spectrum 3 2 2 Energy Filter Parameters The main parameter to optimize energy resolution is the energy filter rise time Generally longer rise times result in better resolution but reduce the throughput Optimization should begin with scanning the rise time through the available range Try 2us 4us 8us 11 2us take a run of 60s or so for each and note changes in energy resolution Then fine tune the ri
22. or special events recorded in the CHAN_USERPSA word Note The Run start time in the buffer header and the event time in the event header are in units of 13 3ns as in the Pixie 4 Table 4 1 Buffer header data format for the Pixie 500 0 BUF NDATA Number of words in this buffer BUF_MODNUM Module number 2 BUF_FORMAT Format descriptor RunTask 0x40T0 or 0x50T0 T bits4 7 indicate channel 0 3 acquired waveforms in 4x trace mode BUF _TIMEHI Run start time high word Yes 4 5 do not match 13 Pixie 500 User s Manual V2 50 XIA 2012 All rights reserved BUF _TIMEMI Run start time middle word BUF_TIMELO 4 3 Input Output Parameters Most of the Pixie 500 input and output parameters are the same as in the Pixie 4 A full description is provided in the Programmer Manual In table 4 2 we list those parameters that are different for the Pixie 500 Most of these differences are handled in the Pixie C library For example while the energy filter in the Pixie 500 operate on a 8ns time scale vs 13 3ns in the Pixie 4 user still enter the filter time in us and the only effect visible to the user is the step size of the allowed filter values Table 4 2 Input output parameter differences between Pixie 4 and Pixie 500 If parameter names in the Pixie Viewer different from the C DSP parameters name is is shown in parentheses FILTERRANGE Legal values 1 6 Legal values 1 6 Legal values 1 6 Range for energy filter ri
23. ow s Device Manager as shown above 8 2 Acquisition Problems oe aS Signal from PMT shows unusual pulse shape Verify the input jumpers are set to the correct termination When taking the signal directly from the PMT without a preamplifier the correct termination is usually 500 Missing peaks in spectra Unusually low count rate Unusually low Live Time Open the OsciLLoscorE and verify that the signal is in range i e that large pulses are not cut off at the upper end of the range 4K and that the baseline is above zero Low efficiency for high energy peaks in MCA spectrum At high rates pulses overlap with the decaying tail of a previous pulse When two or more pulses overlap in this way higher energy pulses are more likely to go out of range gt reduce gain and or adjust the offset If the detector output shows significant ringing or overshoots it can happen that the Pixie 500 triggers twice on the same pulse first on the rising edge then on the overshoot This would be more likely for higher energy pulses because the ringing or overshoot has a larger amplitude gt increase the trigger threshold and or the trigger filter rise time or use the advanced options to pause or for low count rates disable the pileup inspection Data collection in list mode has low DAQ fraction SFDT is a large fraction of the live time Rate at which list mode data is written to file is low The number of events collected in a
24. se time The flat top usually needs only small adjustments For a typical coaxial Ge detector we suggest to use a flat top of 1 2us For a small detector 20 efficiency a flat top of 0 8us is a 10 Pixie 500 User s Manual V2 50 XIA 2012 All rights reserved good choice For larger detectors flat tops of 1 2us and 1 6us will be more appropriate In general the flat top needs to be wide enough to accommodate the longest typical signal rise time from the detector It then needs to be wider by one filter clock cycle than that minimum but at least 3 filter clock cycles Note that a filter clock cycle ranges from 0 026 to 0 853 us depending on the filter range so that it is not possible to have a very short flat top together with a very long filter rise time The Pixie Viewer provides a tool which automatically scans all possible combinations of energy filter rise time and flat top and finds the combination that gives the best energy resolution This tool can be accessed by clicking the Optimize button on the Settings tab Please refer to the Online Help documentation for more details A second option is to create a file series where the energy filter parameters are modified for each file in the series See section 3 6 for more details 3 2 3 Threshold and Trigger Filter Parameters In general the trigger threshold should be set as low as possible for best resolution If too low the input count rate will go up dramatically and noise pea
25. se time or 2x13 3ns 2 2x8ns 2 127x8ns 2 2x10ns 2 flat top in 127x13 3ns 2 127x10ns 2 FILTERRANGE F CHANCSRA B Control bits for Control bits for C checkboxes GATE GATE are ignored are ignored SGA gain Bit 0 7 are used to Bit 0 is used to switch Bit 0 is used to switch switch from 0 85 from 1 0 to 2 9 from 1 0 to 2 9 11 25 FASTLENGTH Legal values 2 63 Legal values 2 63 Legal values 2 63 trigger filter rise time in ns is time in ns is time in ns is time FASTLENGTH FASTLENGTH 8ns FASTLENGTH 10ns 13 3ns FASTGAP Legal values 0 63 Legal values 0 63 Legal values 0 63 trigger filter flat time in ns is time in ns is time in ns is top FASTGAP 13 3ns FASTGAP 8ns FASTGAP 10ns TRACELENGTH Legal values 0 1024 Legal values 0 8192 Legal values 0 8192 time in ns is time in ns is time in ns is TRACELENGTH TRACELENGTH TRACELENGTH 13 3ns 2ns 2 5ns i e range is 0 13 6us i e range is 0 16 4us i e range is 0 20 48us GATEDELAY imoa Ss ignored GATEWINDOW ignored ignored LIVETIMEA B C Three 16 bit words Three 16 bit words form Three 16 bit words form Livetime form a 48 bit number a48 bit number in units a 48 bit number in units in units of 13 3ns 16 of 8ns 32 of 10ns 32 FTDTA B C Three 16 bit words Three 16 bit words form Three 16 bit words form Fast trigger dead form a 48 bit number time in units of 13 3ns of 8ns of 10ns SFDTA B C Three 16 bit
26. t XIA for recommendations on which chassis are suitable for large multi module systems 2 Setting Up 2 1 Installation 2 1 1 Hardware Setup The Pixie 500 modules can be operated in any standard 3U CompactPCI or PXI chassis Chassis following only the CompactPCI standard can be used to operate modules individually To operate several modules together a backplane following the PXI standard must be present Put the host computer or remote controller in the system slot of your chassis Place the Pixie 500 modules into any free slots with the chassis still powered down 4 Pixie 500 User s Manual V2 50 XIA 2012 All rights reserved then power up the chassis Pixie 500 modules are not hot swappable If using a remote controller be sure to boot the host computer after powering up the chassis 2 1 2 Drivers and Software System Requirements The Pixie software is compatible with Windows XP Vista or Windows 7 For the 64 bit version of Windows 7 the PC s RAM must be 4 GB or less Please contact XIA for details on operating Pixie 500 modules with Linux When the host computer is powered up the first time after installing the controller and Pixie 500 modules in the chassis it will detect new hardware and try to find drivers for it A Pixie 500 module will be detected as a new device every time it is installed in a new slot While there is no required order of installation of the driver software the following sequence is recommend
27. toring different amounts of data per event The run types and data formats are described in detail in the Pixie 4 User manual 4 2 Output Data The only differences in output data for the Pixie 500 are the definition of the following list mode data words The BUF FORMAT word in the buffer header is formed by adding 0x4000 to the run task in the 500 MHz version and by adding 0x5000 for the 400 MHz version The Buffer header is thus as shown in Table 4 1 This allows data processing software to distinguish Pixie 4 data from Pixie 500 data digitized at different rates All timestamps in the buffer header event header and channel header are in units of 2 ns 500 MHz or 2 5 ns 400 MHz The smallest increment of timestamps is 8ns 10ns for 400 MHz version Optionally buffer header and event header time stamps can be in units of 13 33ns e g to match timing in a Pixie 4 module The option is controlled by a checkbox in the Run Tab of the Pixie Viewer Time intervals between the waveform samples are 2 ns 500 MHz or 2 5 ns 400 MHz If pulse shape analysis is performed to compute the constant fraction time of arrival the result CHAN _XIAPSA is still in units of 1 256 of a sample interval but a sample interval is 2 ns or 2 5 ns For example if CHAN _XIAPSA 0x0509 in a 500 MHz system the CFD time is 5 9 256 ADC sample steps or 10 0703 ns away from the beginning of the recorded trace There are no flags f
28. words Three 16 bit words form Three 16 bit words form slow filer dead form a 48 bit number a 48 bit number in units a 48 bit number in units time in units of 13 3ns 16 of 8ns 32 of 10ns 32 14 Pixie 500 User s Manual V2 50 XIA 2012 All rights reserved GDTA B C Three 16 bit words ignored ignored gate dead time form a 48 bit number in units of 13 3ns 16 15 Pixie 500 User s Manual V2 50 XIA 2012 All rights reserved 5 Hardware Description The Pixie 500 is a 4 channel unit designed for gamma ray spectroscopy and waveform capturing The functional building blocks are similar to the Pixie 4 please refer to the Pixie 4 User manual for details The main difference is the use of a faster ADC and FPGA to process the ADC data stream as indicated in Figure 5 1 When using external signals note that the Pixie 500 MMCX inputs are labeled correctly as DSP OUT and IN OUT For Pixie 4 modules the labels are swapped On the Pixie 500 an external input signal should therefore be connected to the IN OUT connector not DSP OUT as described in the Pixie 4 manual Figure 5 1 Functional block diagram of the Pixie 500 front end data acquisition and signal processing card The ADCs are either 12bit 500 MHz or 14bit 400 MHz models 6 Theory of Operation The principles of operation for the Pixie 500 are the same as for the Pixie 4 Please refer to the Pixie 4 User manual for a detailed description 7 Operating Multip
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