PIXIE-4 Online Help
Contents
1. amp hitOs 8 0 1 specific channel hit in each of 9 specific modules others don t matter 16 h0901 MC lt amp hitOs 8 0 10 modules amp amp hit1s 8 0 2 specific channels hit in each of 9 specific module others don t matter 16 h0A00 MC lt amp hitOs 9 0 II 1 specific channel hit in each of 10 specific modules others don t matter 16 h0A01 MC lt amp hitOs 9 0 amp amp hit1s 9 0 2 specific channels hit in each of 10 specific module others don t matter 11 modules 16 h0B00 MC lt amp hitOs 10 0 16 h0B01 MC lt amp hitOs 10 0 12 modules 16 hOC00 MC lt amp hitOs 1 1 0 16 h0C01 MC lt amp hitOs 1 1 0 13 modules D 1 specific channel hit in each of 11 specific modules others don t matter amp amp hit1s 10 0 2 specific channels hit in each of 11 specific module others don t matter 1 1 specific channel hit in each of 12 specific modules others don t matter amp amp hitts 11 0 2 specific channels hit in each of 12 specific module others don t matter 16 hODO0 MC lt amp hitOs 12 0 1 specific channel hit in each of 13 specific modules others don t matter 16 h0D01 MC lt amp hitOs 12 0 amp amp hit1s 12 0 2 specific channels hit in each of 13 specific module others don t matter PIXIE 4 Online Help V1 61 XIA 2008 All rights reserved 5 2 2008 UntitledO 14 group tests 16 h2. 1 or more in either not both modules MC lt multi00 gt multi_reqt multi01 gt multi_req1 2 or more in either not both modules MC lt multi00 gt multi_reqt multi01 gt multi_req1 3 or more in either not both modules MC lt multi00 multi_reqt multi01 multi_req1 1 in either not both modules MC lt multi00 multi_req1 multi01 multi_req1 2 in either not both modules MC lt multi00 multi_req1 multi01 multi_req1 3 in either not both modules MC lt pa00 pa01 pa02 pa03 one or more pairs out of 4 pairs a pair is two channels hit MC lt pa00 pa01 pa02 pa03 one or more pair in one module not both MC lt pa00 pa01 pa02 pa03 exactly one pair in one or both modules MC lt pa00 pa01 pa02 pa03 exactly one pair in one not both module MC lt po00 po01 p002 po03 one or more pairs out of 4 pairs a pair at least one of two channels MC lt p000 po01 po02 po03 one or more pair in one module not both MC lt p000 po01 p002 po03 exactly one pair in one or both modules MC lt po00 po01 p002 po03 exactly one pair in one not both module 3 module tests 16 h0300 16 h0301 16 h0302 16 h0303 16 h0304 MC lt MOCO amp MOC1 amp IMOC2 amp IMOC3 M1CO amp IM1C1 amp IM1C
3. The GFLT signal must be a LVTTL signal i e O OV 1 3 3V A second option for the MMCX front panel input is to configure it to contribute to the STATUS line on the backplane This is a wire OR line connected to all modules in a backplane segment If the MMCX input is high the module will pull down the wire OR line this constitutes a logic 1 for this line The state of the STATUS line can be recorded during event processing see below PDM control For making coincidence decisions between modules it is recommended to use XIA s logic and preamp power module the PXI PDM It is meant to reside in slot 2 The PXI PDM has no PCI interface and thus is programmed by a Pixie 4 module in the neighboring slot To enable a module to program the PXI PDM the checkbox Module programs PDM to immediate left has to be set The Pixie 4 module then sends the PDM control pattern to the PDM The PXI PDM receives the Pixie 4 s hit pattern through the PXI Star Trigger lines A module can be set to not send out its hit pattern the PDM assumes a default 0000 by unchecking the box Send local hit pattern to PDM in slot 2 Note that due to the architecture of the PXI Star Trigger a module in slot 2 must not send signals on this backplane pin Therefore for a module in slot 2 this checkbox is automatically cleared The coincidence decision in the PDM is determined from the full 48bit hit pattern of the modules in slots 3 14 and the PDM control patte
4. before recording and processing an event This is called the local coincidence test A global coincidence test can be applied using a PXI PDM in slot 2 Each module can send its hit pattern to the PXI PDM The module in slot 2 defines which test the PXI PDM should apply see above and the PXI PDM outputs the result of the test on a shared backplane line In addition each module can add the negative result of its local test to the global test essentially vetoing those events that do not pass its local test for all modules This allows one or more master trigger modules to influence acquisition for all modules Limited module coincidence requirements can thus be applied even without a PXI PDM With the checkboxes in the Module Coincidence Setup each module can thus be set to accept events if a only the local coincidence test is passed check local b only the global coincidence test is passed check global c either the local OR the global coincidence test is passed check global and local d the global test AND all relevant local tests pass check global and local adds to global The Coincidence Pattern and Coincidence Window for each module are shown for reference only Examples 1 To require a local coincidence of channels 0 1 2 3 or both set the coincidence pattern to 0x9008 in the ModuleRegisterPanel and check only the local test box in the Chassis Register Panel 2 To require coincidence of channels 0
5. us PSA Start PSA End CFD Threshold ChanCSR Channel CSRA and Channel CSRB Coinc Coincidence Pattern Coincidence Window MCA Cut Off Energy Binning Factor TAU Tau us Intergrator Integrator ModCSR All module coincidence settings and backplane options except front panel GFLT After selecting source destination and parameters click on the Copy button to execute the copy operation e ExtractPanel Settings gt Extract This panel can be used to extract parameter settings from a file to selected modules and channels The source file is specified at the top of the panel Click on the Find button to locate the source file Parameters to be extracted and destination modules or channels are selected in the same manner as in the CopyPanel Click the Extract button to execute the operation AllFilesPanel Settings gt Files Paths This panel gives you access to the underlying files of the Pixie 4 software Usually these files are already loaded in the memory of the Pixie 4 Viewer You only have to change these files when you receive updates from XIA The directory locations are specified as complete not relative search paths the DSP Path for the DSP code and the FPGA Path for the trigger filter FPGA configuration Use a colon as the separator between drive name directory and subdirectories Do not use backslashes For example PIXIE 4 Online Help V1 61 XIA 2008 All rights reserved 5 2 20
6. channel individually Be sure to select the channel of interest prior to changing these variables Use the mouse to zoom in on peaks of interest The Fit menu allows you to make Gaussian fits to peaks in the histograms The fit range can be set channel by channel in the Min and Max fields or by placing cursors on the spectrum with the mouse The Fit menu starts a fitting routing for one or all channels The routine does take a constant background term into account though its value is not displayed The fit results that are displayed include the peak position the number of counts in the peak and its relative and absolute full width at half maximum FWHM calculated from the Gaussian fit For best results be sure to extend the fit range to cover some of the constant background The Zoom buttons above the graph can be used as shortcuts to zooming operations with the mouse The Reset Scale button resets the scaling of the MCA to 1 bin i e it undoes any calibration entered through the Peak field All Run Statistics The run statistics for all modules and channels are displayed in the All Run Statistics panel It also shows the time and date of run start and stop and the source where the statistics were last read from The information can be refreshed during a run by clicking the Update button it can be saved to or read from an ifm file with the Files menu The DAQ Fraction is an estimate of the fraction of the lab time a modu
7. configuration as the 18 slot chassis only fewer slots Specify the Pixie 4 modules Next select the number of Pixie 4 modules in the system Then specify the PXI slot number in which each module resides Note If using the 18 slot chassis the Pixie 4 module designated as module 0 must reside in the first bus segment any of slots 1 6 Finally click Start Up System In the IGOR history window a message will show if the modules have been initialized successfully You will now see the main Pixie4 Run Control Panel from which all work PIXIE 4 Online Help V1 61 XIA 2008 All rights reserved 5 2 2008 UntitledO 3 is conducted The tabs in the Pixie4 Run Control Panel are arranged in logical order from left to right For most of the actions the Pixie Viewer interacts with one Pixie 4 module at a time The number of that module is displayed at the top right corner of the Pixie4 Run Control Panel inside the Module control Next to the Module control is the Channel control which specifies the current channel the Pixie Viewer is interacting with The Module and the Channel are the target for all actions executed from the Pixie Viewer Proceed with the steps below to configure your system 1 Inthe Calibrate tab click on the Oscilloscope button This opens a graph that shows the untriggered signal input Click Refresh to update the display The pulses should fall between about 1600 and 15000 on the left axis If no pulses are
8. entered through the Peak field List Mode Traces After a list mode run has finished the acquired waveforms and event data can be displayed on an event by event basis in the List Mode Traces panel The most recently acquired data file will be searched for the event requested in the Trace number field The display will show the traces from the selected module and the associated time stamps energies and PSA values for those channels that reported a hit in this event Also shown are the hit pattern and event timestamp Traces and energies are scaled as 16 bit numbers Note that the ADC traces shown in the Oscilloscope are raw 14 bit numbers i e ADC traces have values divided by 4 Other displays show the Event times and the Hitpattern The last 4 bits of the hit pattern mark the channels recorded bits 0 3 for channel 0 3 and bits 8 11 mark the channels reporting a hit bits 8 11 for channel 0 3 Bit 5 shows the result of the local coincidence test bit 6 the level of the Status line and bit 7 the result of the global coincidence test Bits 4 12 15 are reserved In order to display traces from an earlier experimental run one needs to change the Data File name by entering it directly in the Data File control or clicking the Find button To see the response of the energy and trigger filters for the current event click on Digital Filter which opens the Filter Display This window is mainly intended for diagnostic purposes For
9. lt MOCO amp MOC1 amp IMOC2 amp MOC3 M1CO amp M1C1 amp IM1C2 amp M1C3 2 specific channels hit in either module no others 16 h0202 MC lt MOCO amp M0C1 amp MOC2 amp MOC3 M1CO amp M1C1 amp M1C2 amp IM1C3 3 specific channels hit in either module no others 16 h0203 MC lt MOCO amp MOC1 amp MOC2 amp MOC3 I M1CO amp M1C1 amp M1C2 amp M1C3 II 4 specific channels hit in either module no others 16 h0204 MC lt MOCO M1C0 Il 1 specific channel hit in either module others don t matter 16 h0205 MC lt MOCO amp M0C1 I M1C0 amp M1C1 2 specific channels hit in either module others don t matter 16 h0206 MC lt MOCO amp M0C1 amp MOC2 I M1C0 amp M1C1 amp M1C2 I1 3 specific channels hit in either module others don t matter 1610207 MC lt MOCO amp IMOC1 amp MOC2 amp IMOC3 M1C0 amp IM1C1 amp IM1C2 amp M1C3 Il 1 specific channel hit in either not both modules no others 16 h0208 MC lt MOCO amp MOC1 amp MOC2 amp IMOC3 M1C0O amp M1C1 amp IM1C2 amp M1C3 2 specific channels hit in either not both modules no others 16 h0209 MC lt MOCO amp M0C1 amp MOC2 amp IMOC3 M1C0 amp M1C1 amp M1C2 amp M1C3 3 specific channels hit in either not both modules no others 16 h020A MC lt MOCO amp MOC1 amp MOC2 amp MOC3 M1CO amp M1C1 amp M
10. more modules po01 p002 po03 p004 po05 exactly one pair in one module 16 h0400 MC lt amp hitOs 3 0 1 specific channel hit in each of 4 specific modules others don t matter 16 h0401 MC lt amp hitOs 3 0 amp amp hit1s 3 0 2 specific channels hit in each of 4 specific module others don t matter 5 modules 16 h0500 MC lt amp hitOs 4 0 Il 1 specific channel hit in each of 5 specific modules others don t matter 16 h0501 MC lt amp hitOs 4 0 amp amp hit1s 4 0 2 specific channels hit in each of 5 specific module others don t matter 6 modules 16 h0600 MC lt amp hitOs 5 0 1 specific channel hit in each of 6 specific modules others don t matter 16 h0601 MC lt amp hitOs 5 0 7 modules 16 h0700 MC lt amp hitOs 6 0 16 h0701 MC lt amp hitOs 6 0 8 modules 16 h0800 MC lt amp hitOs 7 0 amp amp hit1s 5 0 2 specific channels hit in each of 6 specific module others don t matter Il 1 specific channel hit in each of 7 specific modules others don t matter amp amp hit1s 6 0 2 specific channels hit in each of 7 specific module others don t matter Il 1 specific channel hit in each of 8 specific modules others don t matter 16 h0801 MC lt amp hitOs 7 0 amp amp hit1s 7 0 2 specific channels hit in each of 8 specific module others don t matter 9 modules 16 h0900 MC lt
11. of event data is stored in a file with name extension dat This is an ASCII file For long list mode runs with many spills this file can become much larger than the binary file If you do not need he ASCII data you can disable the dat file by unchecking the Auto process list mode data in the Data Record Options panel mca For both list mode runs and MCA runs MCA spectrum data are stored in a file with name extension mca if you select Auto store spectrum on the Data Record Options panel This is a binary file consisting of 32bit unsigned integers It includes MCA data for all modules ordered from channel 0 of module 0 to channel 3 of the last module set Module settings are stored in a file with name extension set after each run if you select Auto store seitings on the Data Record Options panel Run statistics can also be extracted from this file This PIXIE 4 Online Help V1 61 XIA 2008 All rights reserved 5 2 2008 UntitledO 21 is a binary file consisting of 16bit unsigned integers It is equivalent to the settings files saved from the Settings tab ifm For both list mode runs and MCA runs run statistics information are stored in a file with the extension ifm if you select Auto store statistics in the Data Record Options panel Start Run After setting all parameters you can start a run to take data During the run the Run Time control shows the remaining time for MCA runs or
12. overall multiplicity 16 h001X MC lt multi_all gt multi_req2 multi_req2 defined above X 1 F 16 h002X MC lt multi_all multi_req2 X 1 F single module tests can actually be done in P4 with local contributes to global option 16 h0100 MC lt MOCO amp MOC1 amp MOC2 amp MOC3 1 specific channel hit no others 16 h0101 MC lt MOCO amp MOC1 amp MOC2 amp MOC3 2 specific channels hit no others 16 h0102 MC lt MOCO amp MOC1 amp MOC2 amp MOC3 3 specific channels hit no others 16 h0103 MC lt MOCO amp MOC1 amp MOC2 amp MOC3 4 specific channels hit 16 h0104 MC lt MOCO 1 specific channel hit others don t matter 16 h0105 MC lt MOCO amp MOC1 2 specific channels hit others don t matter 16 h0106 MC lt MOCO amp MOC1 amp MOC2 3 specific channels hit others don t matter asa le le el Nee ee He a r 16 h0111 MC lt multi00 gt multi_req 1 or more 16 h0112 MC lt multi00 gt multi_req 2 or more 16 h0113 MC lt multi00 gt multi_req 3 or more 16 h0114 MC lt multi00 multi_req M1 16 h0115 MC lt multi00 multi_req H2 16 h0116 MC lt multi00 multi_req 3 2 module tests 16 h0200 MC lt MOCO amp MOC1 amp IMOC2 amp MOC3 M1CO amp M1C1 amp IM1C2 amp M1C3 1 specific channel hit in either module no others 16 h0201 MC
13. scanning of a large range of Tau values You could change the Decay Time Limits of each channel by changing the Channel control on the left upper corner of the Pixie 4 Run Control panel At any time the Pixie 4 module used to carry out this optimization is the current module i e the module indicated by the Module control on the left upper corner of the Pixie 4 Run Control panel So if you want to use a different module change the Module number before you set the Decay Time Limits for each channel e Oscilloscope Calibrate gt Oscilloscope The Oscilloscope shows 8192 untriggered ADC samples from the input for each channel The time between samples can be set using the dT variable The display is updated through its Refresh button The DC offset of the preamplifier signal has to be compensated for in order to bring the DC coupled input into the ADC range The exact DC value has no bearing on the acquired spectrum and its origin which is always at zero The DC adjustment is used only to ensure that the signals to be measured fall comfortably into the ADC range When clicking the Adjust Offsets button the Pixie 4 Viewer will set the DC offset to a percentage of the full ADC range specified in the Offset control The offset calibration must be performed with the preamplifiers connected to the Pixie 4 inputs and with both the preamplifier power and detector HV switched on One should also repeat the offset calibration each tim
14. scintillator applications where event energies can be derived by setting the energy filter flat top long enough to cover the whole scintillation pulses 2 Ignore energy filter gap sum when reconstructing event energy This is useful for step pulses whose amplitude is the difference between the high and low steps 3 5 Same as 1 but the energy is multiplied by a factor 2 4 or 8 respectively This is useful for very fast pulses that do not have a lot of area under the peak and thus will show up only at the very low end of the spectrum e ModuleRegisterPanel Settings gt Module Register The Module Register Edit Panel controls several module wide parameters Edit Required Hit Patterns In this section you can select the Coincidence Pattern that defines which channels have to contribute to an event to make it acceptable For example you might be only interested in events in which only a single channel was hit or in any event in which more than two channels contributed Below is a description for functions within a module Module coincidence functions are described under ChassisRegisterPanel For each event the Pixie 4 first reads which channels contributed before reading any further data This Hit Pattern is a 4 bit number e g 0001 if only channel O contributed or 1111 if all channels PIXIE 4 Online Help V1 61 XIA 2008 All rights reserved 5 2 2008 UntitledO 8 contributed By setting the checkboxes you can require that
15. visible or if they are cut off above 16384 or below 0 click Adjust Offsets to automatically set the DC offset There is a control called Baseline on the Oscilloscope which can be used to adjust the DC offset for each channel If the pulse amplitude is too large to fall in the display range decrease the Gain in the Calibrate tab of the Pixie4 Run Control Panel Since the offsets might drift for example after changes in input count rate it is useful to leave the display open and check the offsets once in a while 2 In the Calibrate tab input an estimated preamplifier RC decay time for Tau in us then click on Auto Find to determine the actual Tau value for the current channel of the current module Repeat this for other channels if necessary The Tau finder works best for a Tau value from 20 us to 200 us 3 In the Settings tab click on Save to save the system parameters found so far You can save the settings into either an existing settings file or a new file 4 Click on the Run tab set Run type to 0x301 MCA Mode Polling time to 1 second and Run time timeout to 30 seconds or so then click Start Run After the run is complete select the Analyze tab and click on the MCA Spectrum button The MCA spectrum shows the MCA histograms for all four channels You can deselect other channels while working on only one channel You can do a Gauss fit on a peak by entering values in the Min and Max fields as the limits for a Gauss
16. 08 UntitledO 16 use D XIA data rather than D XIA data File and Path names should not exceed 80 characters Calibrate If not all described controls are visible click on the More button at the bottom of the panel Analog Signal Conditioning In the Analog Signal Conditioning section you can set the gain and DC offset for the selected channel and module Note that the ADCs are dc coupled to the Pixie 4 inputs and thus compensation for any DC offset is necessary You will rarely have to set this manually as the DC offsets can be adjusted automatically through clicking on Adjust Offsets on the Oscilloscope The gain and offset settings are given in units of V V and V respectively The voltage gain computed is the ratio between the pulse height at the module input to the pulse height at the ADC input Note that the ADC has a 2 2V input range Histogram Control This section shows the parameters controlling the operation of the multichannel analyzer built into the DSP memory Energy values are calculated to 16 bit fixed point numbers This would correspond to a 64k spectrum To map the full energy range into the available 32k spectrum one has to combine bins At minimum 2 bins have to be combined into one so the Binning Factor has to be set to 1 combining 2 1 bins Higher binning factors can be useful for low count rate or low resolution applications If you want to see a certain range of the spectrum at higher resolution yo
17. 1020 MC lt MSUM_g1 gt 2 2 or more modules in first group rest don t care 16 h1021 MC lt MSUM_g1 gt 2 MSUM_all gt 3 2 or more modules in first group OR at least 3 modules overall ARSA tests MO gamma pairs M1 M2 beta pairs 1611100 MC lt pa00 pa01 amp p002 p003 p004 p005 only one pair 2 hits from MO AND exactly one pair gt 0 hits from M1 M2 1611101 MC lt pa00 pa01 I p002 p003 p004 p005 at least one pair 2 hits from MO OR at least one pair gt 0 hits from M1 M2 1611102 MC lt pa00 pa01 I p002 p003 p004 p005 only one pair 2 hits from MO OR at least one pair gt 0 hits from M1 M2 16 h1103 MC lt pa00 pa01 only one pair 2 hits from MO rest don t care 16 h1104 MC lt pa00 pa01 at least one pair 2 hits from MO rest don t care 16 h1105 MC lt pa00 amp p001 p000 amp pa01 amp p002 p003 p004 p005 exactly one pair 2 0 or 0 2 hits from MO AND exactly one pair gt 0 hits from M1 M2 16 h1106 MC lt pa00 amp p001 p000 amp pa01 I po02 p003 p004 p005 Il exactly one pair 2 0 or 0 2 hits from MO OR at least one pair gt 0 hits from M1 M2 default MC lt 1 Module Coincidence Setup Each module always tests the Hit Pattern of contributing channels against the user defined Coincidence Pattern set in the ModuleRegisterPanel
18. 1C2 amp M1C3 PIXIE 4 Online Help V1 61 XIA 2008 All rights reserved 5 2 2008 UntitledO 12 Il 4 specific channels hit in either not both modules no others 16 h020B MC lt MOCO A MICO 1 specific channel hit in either not both modules others don t matter 16 h020C MC lt MOCO amp MOC1 A MICO amp M1C 2 specific channels hit in either not both modules others don t matter 16 h020D MC lt MOCO amp MOC1 amp MOC2 A M1CO amp M1C1 amp M1C2 I1 3 specific channels hit in either not both modules others don t matter 16 h0211 16 h0212 16 h0213 16 h0214 16 h0215 16 h0216 16 h0221 16 h0222 16 h0223 16 h0224 16 h0225 16 h0226 16 h0230 16 h0231 16 h0232 16 h0233 16 h0234 hit 16 h0235 16 h0236 16 h0237 MC lt multi00 gt multi_req1 multi01 gt multi_req1 1 or more in either module MC lt multi00 gt multi_req1 multi01 gt multi_req1 2 or more in either module MC lt multi00 gt multi_req1 multi01 gt multi_req1 3 or more in either module MC lt multi00 multi_req1 multi01 multi_req1 1 each in either module MC lt multi00 multi_req1 multi01 multi_req1 2 each in either module MC lt multi00 multi_req1 multi01 multi_req1 3 each in either module MC lt multi00 gt multi_reqt multi01 gt multi_req1
19. 2 amp M1C3 M2CO amp IM2C1 amp M2C2 amp M2C3 1 specific channel hit in either module no others MC lt MOCO amp MOC1 amp MOC2 amp IMOC3 M1CO amp M1C1 amp M1C2 amp M1C3 M2CO amp M2C1 amp IM2C2 amp M2C3 2 specific channels hit in either module no others MC lt MOCO amp MOC1 amp MOC2 amp IMOC3 M1CO amp M101 amp M1C2 amp M1C3 M2CO amp M2C1 amp M2C2 amp M2C3 3 specific channels hit in either module no others MC lt MOCO amp MOC1 amp MOC2 amp MOC3 M1CO amp M1C1 amp M1C2 amp M1C3 M2CO amp M2C1 amp M2C2 amp M2C3 4 specific channels hit in either module no others MC lt MOCO M1C0 M2CO Il 1 specific channel hit in either module others don t matter 16 h0305 MC lt MOCO amp MOC1 M1CO amp M1C1 M2CO amp M2C1 2 specific channels hit in either module others don t matter 16 h0306 MC lt MOCO amp MOC1 amp MOC2 M1CO amp M1C1 amp M1C2 M2C0 amp M2C1 amp M2C2 3 specific channels hit in either module others don t matter 16 h0311 module 16 h0312 module MC lt multi00 gt multi_req1 multi01 gt multi_req1 multi02 gt multi_req1 1 or more in either MC lt multi00 gt multi_req1 multi01 gt multi_req1 multi02 gt multi_req1 2 or more in either PIXIE 4 Online Help V1 61 XIA 2008 A
20. 3ns increments from FIFO memory If event dead time is a concern the trace length should be set as short as possible In particular if only energies and time stamps are of interest the trace length can be set to zero The PSA Start and PSA End specify the trace range for Pulse Shape Analysis PSA Currently the Pixie 4 supports two types of PSA XIA_PSA and USER_PSA XIA_PSA reports the signal arrival time by measuring the time when the trace reaches a preset percentage level constant fraction of its magnitude The preset percentage threshold can be set defined in the ChannelRegisterPanel The arrival time is relative to the starting time of the trace So for XIA_PSA the PSA Start and PSA End should be set to include the rising edge of the trace USER_PSA is a user defined PSA value calculated by customized user code linked to the general software Action Buttons Channel Channel Register ChannelRegisterPanel Module Module Register ModuleRegisterPanel Chassis Chassis Register ChassisRegisterPanel Copy Copy settings CopyPanel Extract Extract settings ExtractPanel Files Path Files and path AllFilesPanel Load Load settings Save Save settings e ChannelRegisterPanel Settings gt Channel Register Each channel has its own channel control status register CCSRA Click a check box to set or clear particular bits Setting the checkboxes will automatically modify the 16bit register shown in the Setting
21. IXIE 4 Online Help V1 61 XIA 2008 All rights reserved
22. PIXIE 4 Online Help Version 1 61 May 2008 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 5 2 2008 UntitledO 2 e Getting Help for the Pixie 4 There are several ways to get help for the Pixie 4 You can use IGOR s built in help browser to access the Pixie 4 specific help file by selecting Help gt Help Topics from the top menu bar Choose Pixie4 Help in the popup menu on the left and select the appropriate help topic from the list on the right Each Pixie 4 Run Control Panel also has a Help button which directly displays the help topic for that panel In the help topics click on blue underlined links to jump to cross references e Getting Started Preparations 1 If you have a remote controller PCI bridge a first install the driver software for the controller itself on the host PC For NI controllers typically this means installing the default software from the Device Driver Reference CD b power down the host computer ins
23. an be used to break up output data into several smaller files since it will take some time to save the data N should be set to a rather large value i e at least several hundred spills or several thousand seconds Note that a new run will be started after saving i e all run statistics will be reset MCA spectra will be cleared and clocks resynchronized if the in every run checkbox is set in the Synchronization section in the Run Tab Thus enabling this feature is equivalent to manually starting several individual runs with N spills Do not parse list mode file will disable the automatic parsing of the list mode file after the run to build a list of pointers to individual events This is required for Igor to display events in the List Mode Traces graph but may take a long time for large files If disabled you have to manually load the file in the List Mode Traces graph before viewing traces and or energies e Analyze On the top left part of the Analyze tab shows the run time and the measured event rate for the selected module The right part shows for each channel the live time and the input count rate Note that the run time is the sum of time spent in sub runs called spills but ignoring the time it took the host to read out the data from Pixie 4 modules Similarly the live time was measured only while one of the sub runs was ongoing Besides the Update button to refresh the run statistics only there are four buttons in the m
24. an event must match one of the selected hit patterns to be accepted for further processing Any or all hit patterns can be selected if none is selected no events will be accepted if all are selected any event will be selected The hit pattern 0000 can be useful when sharing triggers between modules traces etc will be recorded in the module for channels with the Read Always Bit set in the ChannelRegisterPanel even if there is no hit in the module itself Setting the checkboxes will automatically modify the 16bit coincidence pattern shown in the Settings Tab where it can also be edited directly type Ox to enter a hex number HHHH An example shall illustrate this feature Assume a single module connected to 4 detectors which observe a Na 22 source emitting back to back 511keV gamma rays from positron annihilation Channels 0 and 1 are connected to one pair of back to back detectors and channels 2 and 3 are connected to a second pair of back to back detectors You are interested only in gammas from positron annihilation Thus a coincidence in channel 0 and 1 or a coincidence in channel 2 and 3 is required If all 4 channels were in coincidence that would be fine too So the acceptable hit patterns would be 0011 1100 and 1111 where the right most digit indicates channel 0 and the left most is for channel 3 To achieve the desired behavior you have to select the three acceptable hit patterns in the HitEditPanel by checking the appropria
25. an the event processing rate So the average trigger rate must be kept well below the processing rate Otherwise the data from the remainder of the run will be corrupted The data is stored in various formats see section 3 6 of the user manual for details 0x200 full event data 9 words no waveforms 0x201 full event data 9 words no waveforms 0x202 compressed event data 4 words no waveforms 0x203 compressed event data 2 words no waveforms Fast List Mode is mainly a legacy run type and only marginally faster slightly shorter dead time from event processing than a normal list mode run recording waveforms of zero length MCA Mode MCA mode puts all modules into a typical spectrum only acquisition mode in which there are no list mode data required The event data is not stored in the output buffer but only used to calculate the energy for incrementing the spectrum Runs end after the time specified in Run Time counts down to zero The Maximum no of Events control is set to zero for MCA runs since it is not used to end the run Any Minimum Energy entered in the Histogram Control is ignored for MCA runs Poll Time The polling time indicates the time interval at which the Pixie 4 Viewer checks if the run in the selected modules has ended If so runs are stopped in all modules if they have not stopped already and the data are read out Run Time This variable is used to indicate the total run time for MCA runs or
26. and 1 in Module 0 and no other channel module matters in the ModuleRegisterPanel set the coincidence pattern in Module 0 to 0x8888 and in all other modules PIXIE 4 Online Help V1 61 XIA 2008 All rights reserved 5 2 2008 UntitledO 15 to OxFFFF In the Chassis Register Panel check the global test box for all modules and the local adds to global box for module 0 No PXI PDM is required 3 To require at least 3 channels to be active in all modules use a PDM module in slot 2 and set the PDM control pattern to 0x0013 for the module in slot 3 Make sure the Module writes control pattern box is checked for this module and the Send local hit pattern to PDM box is checked for all modules Then check the global test box for all modules e CopyPanel Settings gt Copy This panel can be used to copy parameter settings from one module to another The source module and channel are selected at the top of the panel The parameters to be copied are organized into list box in the left hand column The right hand column shows the destination channels and modules for the copy operation The Items to copy shown on the Copy Panel and the actual variables to be copied are listed below Items Actual variables to be copied Gain Gain V V Offset Offset V and base percent Filter Energy Filter Rise Time and Flat Top Baseline Cut Trigger Trigger Filter Rise Time and Flat Top Trigger Threshold FIFO Trace Length Delay dT
27. d sending it to the core Bit 6 GFLT required In a larger experiment you may want to exercise control over which events to accept and which to reject based on external logic A logic signal inhibiting event triggers can be distributed on the PXI backplane When bit 6 is set a logic high on the GFLT Veto backplane line will inhibit latching data and issuing triggers for this channel Bit 7 Histogram energies Switch on incrementing an energy histogram in the DSP s MCA memory with this bit You can choose to have histogramming in list mode runs The histograms will continue to be updated over multiple runs started with the resume run command Bit 14 Estimate energy if not hit PIXIE 4 Online Help V1 61 XIA 2008 All rights reserved 5 2 2008 UntitledO 7 If a channel is read out even if it did not report a hit see Read always its energy is normally reported as zero since there was no valid local trigger to capture the value of the energy filter However since the energy filter is computed continuously setting bit 14 will capture the filter value based on the last group trigger distributed within the module or over the backplane This might be useful for channels with occasional very small pulses below the threshold or possibly to capture energy estimates on piled up pulses Note that since the timing of the group trigger is not precise with respect to the non triggering pulse the energy reported is only a rough e
28. e measurement conditions change in any major way e g when the count rate changes greatly All such changes may influence the DC offset value of the preamplifier signal To analyze the noise spectrum of the acquired trace click on the FFT Display button which opens the FFTDisplay To view the effect of the digital filters applied to the ADC traces click on the Show Filters button which opens the ADCFilterDisplay FFTdisplay You can analyze the noise spectrum in the trace captured in the Oscilloscope by observing the Fourier transform of the signal For best results remove any source from the detector and only regard traces without actual events The chart shows a plot of amplitude vs frequency The plot is calibrated such that a sine wave with 100 ADC units amplitude 200 units peak to peak will show up with an amplitude of 100 To convert a noise floor measurement into ADC units sqrt Hz use the variable FFTbin displayed at the top of the chart which tells the width of each frequency bin in the Fourier spectrum The conversion from amplitudes to rms ADC units sqrt Hz is accomplished by multiplying PIXIE 4 Online Help V1 61 XIA 2008 All rights reserved 5 2 2008 UntitledO 18 with 1 sqrt 2 FFTbin Now observe that an ADC unit corresponds to 61uV Using the known gain of the Pixie 4 you can convert the noise into an input noise voltage density measured in V sqrt Hz Or given a particular energy calibration the noise densi
29. e thus calculates the required additional window width to compensate for any such difference displays it in the Required additional width field and ensures that the User added width is at least this value If longer delays between channels are expected from the physics of the experiment this added width can be increased up to a value of 200ms If the required additional with is later decreased by reducing the difference in peaking times a smaller coincidence window is possible However to avoid modifying a large coincidence window intentionally set by the user the User added width is never decreased automatically Notes 1 Any added coincidence window width will increase the time required to process an event and thus reduce the maximum count rate 2 In run types 0x100 0x203 pulses occurring during the readout of data after the end of the coincidence window are lost The readout may take several microseconds longer if waveforms are to be recorded 3 The cut off at the end of the coincidence window is precise to within 13 3ns PIXIE 4 Online Help V1 61 XIA 2008 All rights reserved 5 2 2008 UntitledO 9 Group Trigger Timestamp Set this checkbox to record individual timestamps for all channels in group trigger mode rather than the identical time stamps based on the last group trigger Normally in acquisitions with shared group triggers all channels record the identical timestamp of the last group trigger for th
30. ed The Sum menu gives you three options of summing the spectrum You can either sum the range defined by the Min and Max fields without any corrections sum the range and subtract the background or sum the entire MCA Summing is performed on all four channels at the same time The calculated Sum is displayed in the Peak Area field and the MCA maximum of the sum range is displayed in the Peak field The Files popup menu allows to store individual spectra and read back stored spectra from disk PIXIE 4 Online Help V1 61 XIA 2008 All rights reserved 5 2 2008 UntitledO 23 There are three operations Save MCA to Igor text file will save the current MCA 4 channels as a scaled wave with some added comments in a text file This can be useful to import data into other applications Read MCA to Igor text file will read back a Igor text file saved as above Extract MCA from binary file will read MCA data for the current module from a binary file such as the mca file automatically saved at the end of the run The file is assumed to be in 32bit unsigned integer format You can Update the MCA during a run at any time The MCA source field displays where the MCA was last read from e g from the module s memory or a specific file The Zoom buttons above the graph can be used as shortcuts to zooming operations with the mouse The Reset Scale button resets the scaling of the MCA to 1 bin i e it undoes any calibration
31. fit You can also use the mouse to drag the Cursor A and B in the MCA spectrum to the limits of the fit Enter the true energy value in the Peak field to calibrate the energy scale If you are not getting a nice looking spectrum you may need to adjust some settings such as filter rise time and flat top etc Refer to the User s Manual for details Pixie 4 Control Panel The Pixie4 Run Control Panel is displayed on the desktop after starting the IGOR experiment file Pixie4 pxp Using the four control tabs arranged in logical order from left to right you can set up the system set run parameters take data and view the results Control Tabs Settings Calibrate Run Analyze It also has four buttons on the bottom of the panel Start System can be used to re initialize the modules More will show additional controls on the control panel Help will open this help file at the entry corresponding to the currently active tab PIXIE 4 Online Help V1 61 XIA 2008 All rights reserved 5 2 2008 UntitledO 4 About will show software and hardware version information e Settings The Settings Tab of the Pixie 4 Run Control Panel contains parameters that control the operation of the Pixie 4 Most settings are changed on a channel by channel basis Controls in the ModuleRegisterPanel affect the module as a whole controls in the ChassisRegisterPanel are used to set up interactions between modules The Settings Tab also contains co
32. iddle of the tab opening the following graphs and panels MCA Spectrum Pulse height spectra accumulated in the internal Pixie 4 memory can be displayed after pressing the MCA Spectrum button Pulse heights are computed to 16 bits precision i e correspond to 64k spectra As the memory allows for only 32k words per channel bins have to be combined according to the Binning factor for each channel in the Histogram Control You can select the module you want to inspect and you can add or remove individual channel displays by clicking the MCA check boxes The Sum MCA checkbox controls display of the clover addback spectrum Gray fields indicate values can be edited The Fit menu allows you to make Gaussian fits to peaks in the histograms The fit range can be set channel by channel in the Min and Max fields or by placing cursors on the spectrum with the mouse The Fit menu starts a fitting routing for one or all channels The routine does take a constant background term into account though its value is not displayed The fit results that are displayed include the peak position the number of counts in the peak and its relative and absolute full width at half maximum FWHM calculated from the Gaussian fit For best results be sure to extend the fit range to cover some of the constant background To calibrate your energy scale you can after the fit type the true energy value into the field Peak and the scale will automatically be adjust
33. information how to use the Pixie 4 for more detailed pulse shape analysis please contact XIA Filter Display This graph is used to see the simulated response of the energy and trigger filters in an event You can browse the leading edge trigger filter response and the energy filter response of individual events The latter requires a trace length of at least twice the peaking time plus the gap time to be displayed The trace is shown in red The trigger filter is shown in blue and the energy filter is shown in green Note that only a simple difference filter is displayed for the energy filter without the corrections for baseline and decay of the pulse used in the energy calculations List Mode Spectrum Pulse height spectra can be reconstructed from list mode data stored on the disk The file shown in the Data File field will be processed and the resulting histograms will be displayed for the selected Pixie 4 module Use Read after changing the data file to process the new data and Histo to update the displayed spectrum The full spectrum length is equal to 64k channels Use No of bins and Delta E settings to compress the spectrum such that it fits the display Hint use 8000 and 4 to see the full range of data and then adjust these numbers to zoom into the range of interest The number of bins PIXIE 4 Online Help V1 61 XIA 2008 All rights reserved 5 2 2008 UntitledO 24 and the delta E variables are kept in memory for each
34. is event Since waveforms are captured based on the group trigger this ensures that within a data record traces and timestamps are correlated However if no waveforms are recorded there is no time of arrival information of possible delays between channels Setting the checkbox preserves the time difference information See the user manual for details Note that since only trigger enabled channels latch time stamps if the box is checked this number is only valid for trigger enabled channels Clover Addback To support 4 fold clover detectors there is a further option to sum energies from individual channels in events with more than one hit and bin them into an addback spectrum This function is enabled with the checkbox Sum channel energies for addback MCA The Pixie 4 module will thus generate 4 channel MCA and one addback MCA at the same time If clover addback is selected there is the further option to bin into the individual channel MCAs either energies from all events or only energies from events with hits in a single channel Clover addback is currently only supported in MCA mode e ChassisRegisterPanel Settings gt Chassis Register The Chassis Setup Panel controls several system wide parameters Backplane Options Trigger share mode As described for the ChannelRegisterPanel if group trigger operation is requested each channel will respond to a distributed trigger rather than its own local trigger Triggers are always dis
35. le is taking data As described above Run Time and Live Time measure only the time a module was actively taking data but not the time to setup a run or the time a module is waiting for readout by the host Thus Run Time is always smaller than the elapsed Lab time i e the difference between date time of run start and run stop DAQ Fraction is defined as Run Time Current date time run start date time 100 and thus gives an estimate of the time lost for readout etc After a run is finished the run stop time replaces the current time Note that Run Time is read from the module while the date time is obtained from the host computer to a precision of 1s DAQ Fraction is therefore not a precise number In list mode runs the time to read out one spill is about 0 025s per module The DAQ Fraction will drop significantly if the time to fill the memory approaches this value To maximize the DAQ Fraction a run in 32 buffer spill mode b make sure the polling time is significantly smaller than the fill time c define only those channels actually used as good and d minimize the amount of waveform captured or run in a compressed list mode to store more events in the same amount of memory For example with 4 channels active in mode 0x103 the memory will hold 744 32 23 808 events so at a count rate of 23kcps the memory will fill in about 1s and be read out in less than 0 1s which results in a DAQ Fraction of more than 91 P
36. ll rights reserved 5 2 2008 UntitledO 13 16 h0313 MC lt multi00 gt multi_req1 multi01 gt multi_req1 multi02 gt multi_req1 3 or more in either module 16 h0314 MC lt multi00 multi_req1 multi01 multi_req1 multi02 gt multi_reqt 1 each in either module 16 h0315 MC lt multi00 multi_req1 multi01 multi_req1 multi02 gt multi_reqt 2 each in either module 16 h0316 MC lt multi00 multi_req1 multi01 multi_req1 multi02 gt multi_req1 3 each in either module 16 h0330 MC lt 16 h0331 MC lt 16 h0332 MC lt 16 h0333 MC lt A a ao nnn A a pa00 16 h0334 MC lt 16 h0335 MC lt 16 h0336 MC lt 16 h0337 MC lt aioi alin a ae N po00 4 modules pa00 pa01 pa02 pa03 pa04 pa05 one or more out of 6 pairs a pair is two ch hit pa00 pa01 pa02 pa03 pa04 pa05 one or more pair in one module not more pa00 pa01 pa02 pa03 pa04 pa05 exactly one pair in one or more modules pa01 pa02 pa03 pa04 pa05 exactly one pair in one module p000 po01 p002 po03 p004 po05 one or more out of 6 pairs a pair is one of two ch hit N po00 po01 p002 po03 p004 po05 one or more pair in one module not more p000 po01 p002 po03 p004 po05 exactly one pair in one or
37. ly and only MCA information is needed MCA mode but not list mode data then this bit should be set to achieve the highest throughput Note This function is currently being debugged revised Bit 2 Good channel Only channels flagged as good will be read out This setting has no bearing on the channel s capability to issue a trigger There can be a triggering channel whose data are discarded Channels not marked as good will not be included in the automatic offset adjustment Bit 3 Read always Set this bit if you want a good channel to be read out even if it did not report a hit If operated in group trigger mode you will always get a valid waveform This way you can collect waveforms not biased by trigger requirements If the signal on the channel crossed the trigger threshold even if not trigger enabled you also get a valid energy and timestamp If bit 14 is set you will get an estimate of the energy even when the signal does not cross the trigger threshold Bit 4 Enable trigger You can switch on any channel s ability to contribute to the event trigger with this bit Bit 5 Trigger positive For channels with triggering enabled this causes triggering on the rising edge of the input signal when the bit is set and triggering on the falling edge when the bit is not set The core of the trigger filter FPGA can only trigger on a rising edge So if the bit is not set the FPGA will invert the signal before storing it in the FIFO an
38. make the flat top two notches longer than the signal rise time The sum of energy filter rise time and flat top cannot exceed 127 decimated clock periods If you type in arise time or flat top value that violates this bound the Pixie Viewer will adjust it accordingly The trigger threshold can be set in units of ADC steps You can get an idea of what the noise in your system is by looking at the trace acquired in the Oscilloscope located on the Calibrate Tab Use the mouse to zoom in on parts of the displayed trace s and estimate the noise Optimize Energy Filter An optimization of energy filter settings is carried out by scanning all possible combinations of energy filter rise and flat top within their respective limits specified by the user examining the energy resolution at each combination and picking the optimal combination which gives the best energy resolution Results of this optimization including energy filter rise time flat top and energy resolution are stored in an output file whose name is specified by the user in the beginning of the run Another file which has the same name as the output file but with a different extension tmp is used to store step by step intermediate results Click on Optimize to open the Auto Optimization of Energy Filter panel Before starting the optimization all conditions listed should be fulfilled first This is to ensure that valid MCA spectra will be produced during the optimization and Gauss Fi
39. ntrols used to load save copy and extract settings If not all described controls are visible click on the More button at the bottom of the panel Energy and Trigger Filter In this group of controls you can set the rise times and flat top times for the Energy Filter and Trigger Filter of each channel The units of time are us For a detailed description of filter parameters please refer to the User s Manual There are several filter Ranges for the energy filter with a granularity of 0 027us for filter range 1 1 bit decimation 0 053us for filter range 2 2 bit decimation and so on The trigger filter is always operated at the full ADC sampling rate Its rise time can be varied between 27ns and 413ns Its flat top however is valid between Ons and 387ns The trigger filter will most often use a flat top comparable with the average signal rise time In applications with very short rise times a flat top of zero will give the best pileup rejection performance Employing a trapezoidal filter avoids the kind of ballistic deficit that occurs when a finite rise time signal is used in conjunction with a Gaussian shaper The energy filter flat top time should thus be a little larger than the longest rise time expected The output of the energy filter is sampled one decimated clock cycle before the end of the flat top plus the signal arrival may jitter by up to one decimated clock cycle with respect to the decimated clock You should therefore
40. ontinue This feature is intended to avoid overwriting previous files when Igor only remembers a run number from an earlier run for example after a PC crash Auto store spectrum will store the spectrum data automatically after a run as a binary mca file Auto store seitings will store the run parameters automatically after a run in binary format same as settings file Run statistics can also be extracted from this file Auto process list mode daia will extract the energies and timestamps from the binary data and save them in a dat file in ACSII format This may take a very long time for large data sets Auto store statistics will store the run statistics and run start stop date and time automatically after a run in ASCII format in an ifm file In addition you can choose to automatically Update MCA every N seconds during MCA runs or every N spills during List mode runs N can be selected in the variable control field Run statistics will be updated at the same time You can also manually update the MCA spectrum by clicking the Update button in the MCA Spectrum display PIXIE 4 Online Help V1 61 XIA 2008 All rights reserved 5 2 2008 UntitledO 22 Further you can choose to automatically store data in New Files every N spills during List mode runs or every N seconds during MCA mode runs N can be selected in the variable control field Run statistics will be updated at the same time This feature c
41. otal number of events will be 32 times the Events Buffer times the Number of Spills If the box OR double buffers is checked the module stores 16 data buffers in the first half of the PIXIE 4 Online Help V1 61 XIA 2008 All rights reserved 5 2 2008 UntitledO 20 external memory which then are read out in a fast block read while another 16 buffers are stored in the second half and so on Each readout of 16 buffers counts as one spill The total number of events will be 16 times the Events Buffer times the Number of Spills The modules continue to take data until the number of spills is reached and the host stops the acquisition If neither are checked buffers are read one by one from internal memory The total number of events will be the Events Buffer times the Number of Spills The readout deadtime will be higher in this mode External memory readout is not supported for Rev B modules Synchronization The first check box asks if all runs should Simultaneously start and stop in all modules In almost all multi module systems this will be the case and the box should be checked Synchronization signals are distributed over a PXI backplane line If a Pixie 4 module is present in the crate but not part of the current data acquisition setup it might inhibit the synchronization setup For setups with more than 7 modules in chassis with PCI bridges make sure the Trigger share mode in the ChassisRegisterPanel i
42. overall time out count down for list mode runs If you select multiple spills for list mode runs the number of spills will also count down during the run For list mode runs when the first module reaching the preset maximum number of events stops its run it will also stop the runs in all other modules if Module Synchronization is enabled Then the data buffer of each Pixie 4 module will be read out and saved into a file If more than one spill is requested the run will resume in all modules When the Run Time control counts down to 0 the Pixie 4 Viewer will issue a run stop command to stop the runs in all modules followed by readout of data to file Stop Run If you want to stop a run before it finishes by itself you can click on this button to manually stop it This will end runs in all modules and read out and save the data Data Record Options This panel gives you several options for automating tasks after or during a run They are all checked by default to ensure all data are saved for each data run Auto increment run number will increase the run number in the file name of the data files to avoid overwriting of files In addition if this option is checked Igor will test at the beginning of a run if the output file already exists testing the bin file for list mode runs and the mca file for MCA runs If the file exists Igor will increment the run number and try again after 20 tries it will add _new to the base file name and c
43. pressed event data 2 words no waveforms Since available memory limits the number of events that each module can store in its buffer the Pixie Viewer computes the maximum number of events When the maximum is reached the run is stopped and the buffer is read out For a longer run in list mode you can request several spills or buffer fills For example if you request a run with 10 spills you will get 10 list mode buffers worth of data At start of the first run all previous run history is cleared e g MCA memory and run and live time information The next nine sub runs are started with a Resume Run command which leaves previous run information intact Run times and live times and spectra in MCA memory are incremented You can also manually adjust the maximum number of events stored before the run is stopped Some data acquisition systems which are geared towards event by event readout and are not able to handle large buffers may benefit from the capability to reduce the maximum number of events per spill Fast List Mode Fast list mode is an event by event data acquisition run without waveforms Since no traces are read out the data acquisition is faster than a regular list mode however no pulse shape analysis PSA values are available There will also be no run statistics no coincidence testing and no checks if the PIXIE 4 Online Help V1 61 XIA 2008 All rights reserved 5 2 2008 UntitledO 19 event buffer is filled faster th
44. rn as listed below This decision list is implemented in the PDM s firmware with no claim to cover all cases Please contact XIA to request additional cases or to obtain verilog source code to write custom PDM firmware Events are accepted if MC 1 Logic operators are AND amp XOR OR NOT Operators in front of an array hit a b or a b c d are unitary reductions to a single bit e g amp a c b a AND b AND c Variables are defined as follows multi_all multiplicity of all channels 0 48 in any particular event multi_reqi multiplicity requirement 1 its value is 1 for PDMcontrol 0 3 1 4 7 2 for 2 5 8 3 for 3 6 9 0 otherwise multi_req2 multiplicity requirement 2 its value is equal to PDMcontrol 0 3 MxCy Hit bit of module x channel y Module 0 is in slot 3 payy pair yy counting from ch 0 and 1 of Module 0 Channels are ANDed PIXIE 4 Online Help V1 61 XIA 2008 All rights reserved 5 2 2008 UntitledO 11 poyy pair yy counting from ch 0 and 1 of Module 0 Channels are ORed pxyy pair yy counting from ch 0 and 1 of Module 0 Channels are XORed hitNs an array of all channel N hit bits e g hit0s MOC0O M1C0 M2CO Msum_all number of modules active in event Msum_g1 number of modules in group module 0 module 5 active in event case PDM control pattern test and debug overall multiplicity 16 h0000 MC lt 0 always low 16 h0001 MC lt 1 always high
45. rom the leftmost segment to the other segments In the XIA 18 slot chassis this drive direction is hardwired For National Instrument chassis use the NI PXI explorer to configure the chassis backplane Notes Since other backplane lines are used for other Pixie 4 functions e g PXI_TRIG3 for run synchronization it is generally a good idea to configure the backplane to drive all PXI_TRIGx lines from the leftmost segment to the other segments Also for proper functioning of the run synchronization use mode 2 and 3 in systems with more than 7 Pixie 4 modules even if not sharing triggers Rev B modules are always connected to the backplane equiv mode 1 Front Panel Input Settings One option to connect an external GFLT Veto signal to the Pixie 4 system is to use the MMCxX front panel connector on a Pixie 4 module The GFLT signal is distributed via the PXI backplane to all modules and if enabled in the ChannelRegisterPanel a channel only records events where the GFLT signal is logic 0 OV If the Use front panel for GFLT input checkbox is set the current module will internally connect the front panel input labeled DSP OUT to drive the GFLT backplane line Only one device may issue the signal to the backplane If the checkbox is set for one module the function will automatically be disabled for all other modules However it is the user s responsibility to ensure that no other device in the PXI chassis issues signals on this line
46. s Tab We give a brief description of all relevant bits here In the Channel Register Panel they appear in top to bottom order Bit 0 Respond to group triggers only This bit controls waveform acquisition To stop the FIFO and store a waveform a channel must receive a trigger When bit 0 is cleared only the triggers generated in this particular channel are used When bit O is set the triggers will be the distributed triggers from other channels or modules also may include this channel Triggers are always distributed within a module Any channel with trigger enabled will issue a trigger PIXIE 4 Online Help V1 61 XIA 2008 All rights reserved 5 2 2008 UntitledO 6 for distribution and any channel set to group trigger bit O is set will respond to the distributed trigger including those issued by itself A further control in the ChassisRegisterPanel determines how trigger signals are distributed between modules Bit 1 Measure individual live time This bit will in almost all applications be opposite to bit 0 Its setting decides who asserts the live time control When cleared the DSP ensures that during the event interrupt no channel can generate another trigger and latch new event data at least not after the coincidence time window see HitEditPanel below This setting is useful in master slave operation and almost in all cases where list mode data are required On the other hand when channels are operating independent
47. s set to 2 and 3 If you also want all timers in all modules to be reset to zero with the start of the next data acquisition run click the box Synchronize clocks For this feature to be useful all Pixie 4 modules should be operating from the same master clock as described in the user s manual Normally once clocks are synchronized they will stay synchronized until modules are power cycled Therefore the checkbox is cleared at the end of the run preserving time correlation between subsequent runs In some cases it may be beneficial to resynchronize the clocks in every new run i e reset the clock to zero for every new data file To do so check the in every run checkbox Output File You can choose a Base name and a Run number in order to form an output file name The run data will be written to files whose name is composed of both i e base xxx The run number is automatically incremented at the end of each run if you select Auto increment run number on the Data Record Options panel but you can set it manually as well Data are stored in files in either the MCA folder if the run is a MCA run or the PulseShape folder if the run is a List Mode run These files have the same name as the output file name but different extension as described below bin For list mode runs buffer data are stored in a file with name extension bin This is a binary file consisting of 16bit unsigned integers dat For list mode runs a summary
48. stimate It might help to set the flat top time to a large value to make the capturing of the energy filter less time sensitive Bit 10 Compute constant fraction time The DSP can use pulse shape analysis to compute a precise signal arrival time using the digital equivalent of a constant fraction discriminator For this to work correctly the rising part of the signal should be fully contained in the recorded trace The time computed is the arrival time after the start of the acquired waveform in units of 1 256th of an ADC sampling interval This information can be used to replace the recorded channel time which is derived from a digital leading edge discriminator cf the User s Manual The standard DSP code shipped with the Pixie 4 has some pulse shape analysis capabilities already built in One of these functions is a digital constant fraction discriminator It uses an input parameter namely the Threshold percentage The default value is 25 since it is a commonly used threshold fraction for this type of discriminator The result of the computation is the time of signal arrival measured with respect to the start of the acquired waveform The result is written into the channel header in the linear output data buffer cf the User s Manual for details Integrator This variable controls the event energy reconstruction 0 Normal code 1 Use energy filter gap sum only This is equivalent to simply integrating over the pulse It is useful for
49. t of energy peaks on the MCA spectra will generate meaningful results The four channels of a Pixie 4 module can be used to optimize four different Auto Scanning Limits at the same time when the same detector signal is split and input into the four channels This would speed up the scanning of a large range of energy filter rise time and flat top PIXIE 4 Online Help V1 61 XIA 2008 All rights reserved 5 2 2008 UntitledO 5 You could change the Auto Scanning Limits of each channel by changing the Channel control on the left upper corner of the Pixie4 Run Control panel At any time the Pixie 4 module used to carry out this optimization is the current module i e the module indicated by the Module control on the left upper corner of the Pixie 4 Run Control panel So if you want to use a different module change the Module number before you set the Auto Scanning Limits for each channel Pulse Shape Analysis The Trace length and Delay values entered in this group of controls both in units of us govern the waveform acquisition Trace length is the total length of the acquired waveform which can be set independent of the parameters in the Energy and Trigger Filter You can use the delay parameter to move the trigger point within the trace Delay measures the trigger time with respect to the beginning of the recorded trace For ordinary data taking the trace lengths are up to 13 6us for each channel The waveforms will be read in 13
50. tall the PCI bridge in both the host computer and chassis and connect them with the bridge cable c power up the system again chassis first 2 Install Wavemetrics IGOR Pro on the host computer or embedded PC 3 Install the Pixie 4 software from XIA see file readme txt on CD ROM 4 If not already installed install the Pixie 4 modules in the PXl CompactPCl crate with the power switched off Connect detector signals to the Pixie 4 modules using the cables supplied by XIA Then switch on power of the chassis For remote controllers you have to reboot the PC after power cycling the chassis 6 After the host PC booted with Pixie 4 modules present it will report new hardware found When Windows is looking for driver files direct it to the drivers folder in the XIA software distribution A properly installed Pixie 4 module should be listed in Window s Device Manager under Other devices as a Custom OEM PCI 9054 board 7 Find Pixie4 pxp in the installed folder and double click it to open the Pixie 4 Viewer Initial Startup When the Pixie Viewer has been loaded the Pixie Start Up Panel should be prominently displayed in the middle of the desktop It will prompt you to do the following Select PXI chassis type First select the PXI chassis you are using Currently supported are standard 4 slot or 8 slot chassis and the National Instrument 14 slot or 18 slot chassis with 3 PCI bus segments The 14 slot chassis has the same PCI bus
51. te boxes and deselect all other hit patterns by not checking their boxes Note the difference between hit and trigger A hit occurs if a pulse goes over threshold and passes pileup inspection Hits can not be disabled A trigger means there is a hit plus a request for event processing is sent to the module s DSP unit Triggers can be disabled on a channel by channel basis in the ChannelRegisterPanel Channels will be recorded if they have a hit or their Read always bit is set in the ChannelRegisterPanel but only hit channels will have valid energy and timing information Coincidence Window Each channel with a pulse above threshold whether trigger enabled of not contributes to the hit pattern the moment the pulse is validated as not piled up i e energy filter time after rising edge of pulse However if the channel is not trigger enabled its contribution to the hit pattern is cleared after a fixed delay 400ns This is to ensure hits don t linger for channels that are not read out The hit pattern is read for comparison with the coincidence pattern about 50ns after the first pulse is validated If several channels contribute to an event the minimum coincidence window the time period in which delayed channels can contribute to the hit pattern is thus 5Ons A difference in peaking times between channels will cause even channels with simultaneous pulses to contribute to he hit pattern at different times The softwar
52. the baseline after the pulse should be included in the fit region The fitted tau is going to be reported in the Fitted tau control and the deviation between the fitting curve and original ADC trace is shown in the Deviation control Click Tau OK to download the Tau value to the Pixie 4 PIXIE 4 Online Help V1 61 XIA 2008 All rights reserved 5 2 2008 UntitledO 17 module Optimize Tau Clicking Optimize opens a panel that allows automatic scanning of all Tau values within the scanning limit specified by the user examining the energy resolution at each Tau and picking the optimal Tau value which gives the best energy resolution Results of this optimization including the Tau value and energy resolution are stored in an output file whose name is specified by the user in the beginning of the run Another file which has the same name as the output file but with a different extension tmp is used to store step by step intermediate results Before starting the optimization all conditions listed on the Auto Optimization of Decay Time panel should be fulfilled first This is to ensure that valid MCA spectra will be produced during the optimization and Gauss Fit of energy peaks on the MCA spectra will generate meaningful results The four channels of a Pixie 4 module can be used to optimize four different Decay Time Limits at the same time when the same detector signal is split and input into the four channels This would speed up the
53. the overall timeout limit for list mode runs During a run it counts down the remaining time List mode runs end when the Number of Spills is reached or the Run Time is down to zero whichever comes first List Mode Spill Settings Number of Spills The variable indicates the number of repeated runs It is only used in list mode runs Even if set to zero there will be at least one spill List mode runs end when the Number of Spills is reached or the Run Time is down to zero whichever comes first Timeout This variable sets the timeout for each individual spill During a run it counts down the remaining time If it reaches zero the current spill is ended by the host and a new spill starts Events Buffer This variable indicates the maximum number of list mode events the Pixie 4 module can store in its buffer for each run It is automatically set to zero indicating unlimited events for MCA runs The number is calculated automatically if you change the run type but it can be reduced manually Multiple Buffers per Spill There are two options to use the external memory on the Pixie 4 to temporarily store several buffers on board and read them out in a fast block read This method reduced readout dead time because the block read is faster If the box 32 buffers per spill is checked the module stores 32 data buffers in external memory which then are read out in a fast block read Each readout counts as one spill The t
54. tributed within a module Any channel that is enabled to trigger will contribute to the distributed trigger and any channel in group trigger mode will only respond to the distributed trigger including those issued by itself In addition triggers can be distributed over the PXI backplane between modules The field Trigger share mode controls this distribution There are currently 4 modes In mode 0 the module is disconnected from the backplane Group triggers are only distributed between the 4 channels of the module In mode 1 the module is connected to the backplane s wired OR lines This means that any module in mode 1 issues triggers on common backplane lines and every module in mode 1 responds to these triggers Modes 2 and 3 are used in large chassis with more than 8 slots where backplane lines do not support a wire OR across PCI segment boundaries A module in mode 2 receives triggers from the right neighbor builds an OR with its own triggers and sends them to the left neighbor The leftmost module thus receives a daisy chain OR of triggers from all modules and should be set to mode 3 to put these distributed triggers on shared backplane lines PXI_TRIGO PXI_TRIG1 All modules in mode 2 or 3 respond to triggers on these lines i e at the same time Note that the PIXIE 4 Online Help V1 61 XIA 2008 All rights reserved 5 2 2008 UntitledO 10 backplane has to be configured to drive PXI_LTRIGO and PXI_TRIG1 f
55. ty can be expressed as eV saqrt Hz If you click on the Apply Filter button you can see the effect of the energy filter simulated on the noise spectrum ADCEFilterDisplay This graph shows the ADC trace for the selected channel and the response of the slow energy filter and the fast trigger filter together with an estimate of the trigger threshold The display is updated through its Refresh button Notes 1 For best representation of the filters the filter lengths should be an integer multiple of the ADC sampling interval 2 Only a simple trapezoidal difference filter is shown for the energy filter In the actual pulse height calculation corrections are applied that take into account the decay of previous pulses the contribution during the flat top time and long term baseline effects e Run If not all described controls are visible click on the More button at the bottom of the panel Run Control This section sets run type run time and polling time Run Type This popup menu is used to set the run type to one of the following modes List Mode List mode is the general data acquisition run Waveforms energies and time stamps are collected on an event by event basis The data is stored in various formats see section 3 6 of the user manual for details 0x100 full event data 9 words plus waveforms 0x101 full event data 9 words no waveforms 0x102 compressed event data 4 words no waveforms 0x103 com
56. u can enter a Minimum Energy This will discard all energies below the minimum and start binning the spectrum from the minimum energy Bin 0 Emin The minimum energy is not applied in MCA runs Decay Time The Decay Time is the exponential RC time constant of the preamplifier It is required in order to properly calculate corrections to measured energy values To set and measure the decay time enter an estimated value then click on the Auto Find button You can also enter a known good value directly in the control The RC calibration needs to be performed only once for a given preamplifier The result is then stored in the parameter database and can be saved in the settings file by clicking on the Save button in the Settings tab Manual Fit Manual Tau Fitting is done on a channel by channel basis Clicking Manual Fit opens the TauDisplay First choose the channel on which you want to do the manual fit by changing the Channel control on the left upper corner of the Pixie4 Run Control panel Then set proper dT on the TauDisplay panel and click the Run button to read an untriggered trace for the chosen channel The exponential fit range can be set either by putting the Cursors A and B on the trace or changing the Fitting_start and Fitting_end controls on the TauDisplay panel Clicking the Do exponential fit button will perform the exponential fit on the portion of the trace specified by the fitting range If possible some of
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