PulseCounter Neutron & Gamma Spectrometry Software Manual MAXIMUS ENERGY CORPORATION Written by Dr. Max I. Fomitchev-Zamilov Web: maximus.energy TABLE OF CONTENTS 0. GENERAL INFORMATION 1. DEFAULT SCREEN 2. COUNTS SCREEN 3. DETECTOR SCREEN 4. SPECTRUM SCREEN 5. HISTORY SCREEN 6. HISTOGRAM SCREEN 7. SUMMARY SCREEN 8. SETUP SCREEN Email: founder@maximus.energy 0. GENERAL INFORMATION Hardware: PulseCounter hardware comprises a data acquisition device (usually PicoScope) and high-voltage power supply to provide detector bias. PulseCounter continuously acquires data at a specified sampling frequency (see SECTION 8) and performs digital signal processing to recognize negative detector pulses that are counted, plotted and converted into spectrum. Installation: first install PicoSDK, 32-bit version if you are using 32-bit Windows or 64-bit version if you are using 64-bit Windows, then run PulseCounter.exe. Files: PulseCounter.exe - PulseCounter executable (requires.net Framework 4.5); Config.xm l - PulseCounter configuration file that stores program settings between sessions; Presets - folder containing hardware presets (XML files with detector configuration data); Experiment folders - PulseCounter will create an experiment folder for each new experiment that you start; each experiment folder may contain multiple sequence subfolders with the following files (which are written at the end of each experiment): Count.dat - binary file that PulseCounter uses to store all count data; this file is meant to be accessed only by the PulseCounter software; Histogram.png - a picture of counts (CPS/CPM) histogram; History.png - a picture of counts history (CPS/CPM vs. time);
Spectrum.png - a picture of spectrum; PulseXXX.png - when Audit Button is active PulseCounter will save each individual detector pulse into a PNG file for audit purposes (use only when count rate is low, < 1 CPS); HistoryCPM.txt - human-readable, Excel-importable text file of CPM history; HistoryCPS.txt - human-readable, Excel-importable text file of CPS history; Spectrum.txt - human-readable, Excel-importable text spectrum (<Energy, kev>, <count> pairs; one per line); Stats.txt - human-readable summary of the experimental sequence; contains counts and other useful statistics; PulseTrain.txt - when Log PulseTrain Button is active PulseCounter creates this human-readable Excel-importable file that contains timestamp and amplitude of each individual detector pulse recognized by PulseCounter; Raw.bin and RawB.bin - when Log Raw Signal button is active PulseCounter logs raw signal acquired during the experiment into these files (Raw.bin = Channel 1; RawB.bin = Channel 2 when active). Data Storage - data recorded by PulseCounter is stored in <Experiment>\<Sequence><B>.<Remote> directory, where <Experiment> is the experiment name, <Sequence> is a sequence number, <B> is a background flag, and <Remote> is the remote or local computer name that identifies the device that provided data. For example Cs-137\1B.MacBook folder identified 1st background sequence for Cs-137 experiment captured by MacBook device. Program Title Bar - displays information on whether PulseCounter is starting, running or finished. When PulseCounter is running the title bar displays percentage of data acquired vs. data dropped. Under normal circumstances this percentage should be around 100% indicating that no data was dropped because the computer is too slow to process it. If you are consistently getting values that are significantly under 100% close background programs and terminate background tasks that consume significant CPU time and disconnect other USB devices. If these steps don t help then reduce sample rate (see Section 8). Local Button - toggles between Local and Remote modes of operation. In Remote mode this PulseCounter instance acts as a Remote Controller and provides graphic interface for remote devices that connect to this computer via TCP/IP. In principle multiple remote devices running PulseCounter can connect to Remote Controller and push their data that is aggregated and displayed by the Remote Controller. Remote Controller can start, stop and configure remote devices. When the button state is Local this PulseCounter instance controls local device connected to computer via USB. The Local mode is the default mode of operation. Device List - contains names of remote computers that provided data for the Remote Controller. By default the list shows the name of the computer the PulseCounter is running on. Selecting an item from this list sets a filter for browsing recorded data. Selecting ALL allows browsing all data. Selecting an item rebuilds Experiment List Box content (below) to reflect experiments recorded by the selected device.
Experiment List Box - allows specifying name of a new experiment and displays list of recorded experiments for the device selected in the Device List. Select an item from the drop down list to load the the particular experiment. Increment or decrement Sequence to switch between different sequences. Sequence Box - keeps track of the experiment sequence number. E.g. an experiment can have multiple sequences that correspond to Background or Experiment counts (used for statistical significance calculation). When browsing recorded data incrementing / decrementing sequence loads and displays data for that sequence. Background / Experiment Button - allows identifying Experiment or Background sequence. Duration Box - allows specifying experiment duration in minutes. Start Button - starts the experiment. Once clicked the button changes to Stop button to stop the experiment. The experiment will stop when the entire interval specified in the Duration Box elapses. Pause Button - pauses the count (visible only when the count is running). Elapsed Time Box - shows elapsed experiment time in mm:ss format. CPM and CPS Buttons - toggle between displaying counts per minute (CPM) or counts per second (CPS). Pressing this button refreshes all plots and tables accordingly. Live Button - toggles between Live data (i.e. data that is being currently acquired or just has been acquired) and Recorded data (i.e. data that has been previously acquired that you can browse by selecting device, experiment and sequence number). Channel List - displays current data acquisition channel (e.g. Channel 1, Channel 2 or Channel 1&2). Default, Counts, Detector, Spectrum, History, Histogram, Summary and Setup Buttons switch between different PulseCounter screens.
1. DEFAULT SCREEN Allows monitoring majority of data that is being acquired in real-time. Fig. 1. Default screen. Detector Plot - displays detector signal. Spectrum Plot - displays pulse spectrum. History Plot - displays pulse count (CPM or CPS) history. CPM / CPS Box - displays current live CPM / CPS. This box displays zero when browsing recorded data. Mean Bo x - displays CPM / CPS mean for live or recorded data. Deviation Box - displays standard CPM / CPS deviation for live or recorded data. Total Box - displays total counts for live or recorded data. Debug Label - displays the following information: DROPPED: percentage of dropped data samples (happens when the sample rate is too fast or the computer is too slow to handle the data stream); when the percentage is non-zero the Debug Line turns red indicating a problem with data acquisition (see Program Title Bar in GENERAL INFORMATION); DOUBLES: percentage of double-events, e.g. events that are spaced closer than the width of the Detector Plot window apart; REJECTED: percentage of events rejected due to Pile Up, Over-Limit (clipping) or failure to meet Maximum Pulse Width requirements; NOISE: percentage of events that fail to meet Minimum Pulse Width requirements.
2. COUNTS SCREEN Allows comparing two count data sets and computing P-value to establish statistical significance. By default left half of the screen is populated with live counts (which are also displayed on the Default Screen). Fig. 2. Counts screen. From Summary Button - allows populating comparison datasets from Summary Screen by aggregating background sequences into the left data set and aggregating experiment sequences into the right data set. Left Channel Box - displays name of the data acquisition channel (e.g. Channel 1, Channel 2, or Channel 1 & 2) for Live data or displays the name of the loaded recorded data set. Click anywhere within this box to bring up a File Open dialog box to browse for recorded data to be loaded into PulseCounter (click on any file to load the entire data set). Right Channel Box - displays name of the comparison data set. Click anywhere within this box to bring up a File Open dialog box to browse for the recorded data to be loaded into PulseCounter for comparison against data specified in the Left Channel Box.
3. DETECTOR SCREEN Displays larger view of the detector signal. Fig. 3. Detector screen.
4. SPECTRUM SCREEN Displays larger view of spectrum. Click anywhere on the plot to move cursor (vertical red line) to view peak channel / energy and peak height in counts. The cursor automatically snaps to the nearest peak. When the spectrum is calibrated full width half-maximum (FWHM) is also calculated and displayed. Click anywhere on the plot and drag mouse while holding the left mouse button to zoom in. Fig. 4. Spectrum screen. Comp Button - displays comparison spectrum overlay (the comparison spectrum comes from the right/comparison data set specified on the Counts Screen). Hold Button - holds spectrum for 2 seconds without accumulation. This is useful for instantaneous screening of strong sources. Smooth Button - displays 8-point moving average of spectral data to smooth-out noise. Calibrate Button - allows calibrating spectrum and switches from channels to energies. To calibrate spectrum first click on peak you wish to identify, then select peak energy from the Isotope List, then click the Calibrate Button. To reset calibration and switch back to channels select RESET from the Isotope List and click the Calibrate Button. Isotope List - displays the list of available calibration energies indicated as Isotope Energy, kev. To enter additional energies not present in the default list create an Isotopes.txt file and place it in the PulseCounter executable folder and specify values as follows:
<Energy in kev>, <Display Name> Here is an example: 59.5, Am-241 59.5 kev 511, Positron 511 kev
5. HISTORY SCREEN Displays larger view of count history in CPS or CPM. Fig. 5. History screen.
6. HISTOGRAM SCREEN Displays counts histogram in CPS or CPM. Under usual circumstances counts distribution should be normal (Gaussian). Non-Gaussian histogram is indicative of a problem with the experiment. Fig. 6. Histogram screen.
7. SUMMARY SCREEN Displays summary, computes mean, standard deviation and total counts across all experiment and background sequences and establishes statistical significance by computing P-value. Fig. 7. Summary screen. Summary Table - lists all experiment sequences in red and all background sequences in blue. Selecting device from the Device List and selecting experiment from the Experiment List refreshes the summary view with the selected device / experiment combination. Click Delete button to permanently remove a particular sequence (PulseCounter will erase sequence files on disk). Selecting ALL from the Device List aggregates the selected experiment data across all devices. Experiment Summary Plot - displays Means for experiment and background sequences. P-Value Box - displays P-value derived from Student s T-test comparing background and experiment sequences. Significance Box - tells you whether the difference between background and experimental counts is statistically significant (configurable, typically P < 0.05 is statistically significant).
8. SETUP SCREEN Allows configuring PulseCounter software. Fig. 8. Setup screen. Preset Box - displays current preset name, allows choosing from list of available presets, which are typically configuration settings for various detectors. Presets are stored as XML files in Presets folder in the PulseCounter executable directory. Preset name determines preset file name and thus must be compatible with the OS file naming restrictions. Save Button - click to save changes made to the current preset. To create new preset without modifying existing one type new name in the Preset Box prior to clicking the Save button. Delete Button - deletes current preset and resets all fields to default values. Detector Group - allows configuring detector hardware: Bias : detector bias voltage in volts; Range: detector signal range in volts; Trigger: pulse trigger in millivolts, pulses with amplitude below the trigger value will not be recognized by PulseCounter; Channels: specify data acquisition on 1 or 2 channels (2-channel acquisition is available on custom hardware only).
General Group - allows specifying general settings: Data Rate: sample rate of PulseCounter data acquisition hardware; higher sample rate is useful for short pulse spectroscopy but may not allow for smooth operation on slow computers; for most purposes 1 MHz is recommended for neutron spectroscopy and 5 MHz for gamma spectroscopy; frequencies above 6 MHz are supported on custom hardware only. Delay Start: provides small delay after the initial start-up to allow for detector warm up. When you click Start button for the first time PulseCounter will apply bias voltage to detector and the voltage will stay ON until you close PulseCounter program. If you notice spectrum drift immediately after start of the data acquisition increase the Delay Start value to allow sufficient time for detector warm up. Beep On Pulse: beeps every time PulseCounter detects a pulse (audible only when the count rate is below 1 CPS); Beep on Finish: plays TaDa sound when data acquisition completes. Statistics Group - allows specifying significance level (typically 5%) for P-value calculations. Spectrum Group - allows controlling spectrum acquisition: Integrate: when active the area under detector pulse is integrated to establish pulse energy. Otherwise pulse height is used, which is a less accurate measure. PileUp Reject: when active the detector pulses that pile up on top of each other are excluded from spectrum; turning off PileUp Reject will may increase spectrum accumulation rate but will decrease energy resolution by broadening peaks; Recalibrate: click this button to reset spectrum calibration (i.e. switch from energy to channels) and clear the Scale Box. Channels: choose the desired number of spectrum channels. Scale: proportionality factor applied to integrated pulse area when PulseCounter builds spectrum; PulseCounter determines this parameter automatically every time the scale is reset; you can adjust this parameter to expand or compress the spectrum. Pulse Group - allows controlling pulse acquisition and rejection: Min Width: minimum pulse width in microseconds; pulses with shorter width will be rejected and counted as noise; Max Width: maximum pulse width in microseconds, also determines the width of the Detector Plot; pulses with longer width will be rejected and counted as noise; Audit: click this button to store each individual detector pulse in a PNG file; this is useful for pulse shape auditing when the pulse rate is low (<1 CPS); do not use this feature when the pulse rate is high; Inverse Filter: performed optimal-lag pulse shaping deconvolution to improve count rate when pulses overlap and cannot be resolved; this is an experimental feature that requires a lot of computational power; Trapezoidal Filter: will be implemented in the next version of PulseCounter.
Configuration Group AutoSequence: when active, Sequence number will auto-increment at the beginning of each experiment (e.g. when you click the Start button); Auto-Runs: set the number of sequences to be taken automatically back to back; Butterfly: when active interleaves experiment and background sequences during auto-run (useful for statistics gathering); AutoStart: when active data acquisition will start at absolute time specified in the box just under this button. Time Server: IP address or domain name of Windows Time Server (useful for coordinating auto-starting data acquisition on multiple remote devices); the time server will provide common time (usually accurate to within 1 ms) for data acquired by multiple remote devices; Log Raw Signal: store the entire acquired data in binary form; this may create a VERY LARGE file when sample rate is high and experiment duration is long; Log Pulse Train: record PulseTrain.txt; this text file contains timestamp and amplitude of each pulse recognized by PulseCounter, so this could be a very large file if the count rate is high; Remote Folder: specify network location if you want PulseCounter to automatically copy recorded data to another location at the end of an experiment; Remote Server: specify IP address of Remote Controller; when you set anything in this box you designate this copy of PulseCounter as remote device that will communicate it s data via TCP/IP to Remote Controller.