XIA Pixie-4 Express Mounting instructions

Pixie-4 Express
Software Manual
-Coincident Energy Plots -
Version 4.21
May 18, 2016
Hardware Revision: B
Software Revision: 4.21
XIA LLC
31057 Genstar Rd
Hayward, CA 94544 USA
Email: [email protected]
Tel: [phone]; Fax: [phone]
http://www.xia.com/
Information furnished by XIA LLC is believed to be accurate and reliable. However, no responsibility is assumed by
XIA for its use, or for any infringements of patents or other rights of third parties which may result from its use. No
license is granted by implication or otherwise under any patent or patent rights of XIA. XIA reserves the right to
change hardware or software specifications at any time without notice.

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Table of Contents
Safety............................................................................................................................................................3
Warranty Statement ......................................................................................................................................4
Manual Conventions.....................................................................................................................................5
1Introduction...........................................................................................................................................6
1.1 Pixie-4 Express Coincident Energy Plotting Functions............................................................6
1.2 System Requirements................................................................................................................6
1.3 Software Overview ...................................................................................................................6
1.4 Support......................................................................................................................................6
1.5 Principle of Operation...............................................................................................................7
2Installation.............................................................................................................................................8
3Data acquisition settings .......................................................................................................................9
4Offline Analysis..................................................................................................................................10
4.1 File I/O....................................................................................................................................10
4.2 Histogramming Parameters.....................................................................................................11
4.3 Additional Plots.......................................................................................................................11
4.4 Analysis and Export................................................................................................................12
4.5 Time Histograms.....................................................................................................................13
5Examples.............................................................................................................................................15
5.1 Delayed Pulser ........................................................................................................................15
5.2 HPGe and NaI with Na-22 source...........................................................................................16

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Safety
Please take a moment to review these safety precautions. They are provided both for your
protection and to prevent damage to the Pixie module and connected equipment. This
safety information applies to all operators and service personnel.
Specific Precautions
Observe all of these precautions to ensure your personal safety and to prevent damage to
either the Pixie module or equipment connected to it.
Power Source
The Pixie module is powered through a PXI Express (PXIe) chassis. Please refer to the
chassis manual for the correct AC voltage connections. The chassis must be powered down
to insert and remove the module.
User Adjustments/Disassembly
To avoid personal injury, and/or damage, always turn off power before accessing the Pixie
module’s on-board switches and jumpers.
Detector and Preamplifier Damage
Because the Pixie module does not provide power for the detector or preamplifier there is
little risk of damage to either resulting from the Pixie module itself. Nonetheless, please
review all instructions and safety precautions provided with these components before
powering a connected system.
Voltage Ratings
Signals on the analog inputs (gold SMA connectors) must not exceed ± 3.5V. Exceptions
apply for certain attenuation and termination settings, see Appendix.
Signals on the digital inputs (gold MMCX connector and 10-pin 2mm har-link connector)
must not exceed 3.3V.
Servicing and Cleaning
To avoid personal injury, and/or damage to the Pixie module or connected equipment, do
not attempt to repair or clean these units. These modules are warranted against all defects
for one (1) year. Please contact the factory or your distributor before returning items for
service.

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Warranty Statement
XIA LLC warrants that this product will be free from defects in materials and workmanship
for a period of one (1) year from the date of shipment. If anysuch product proves defective
during this warranty period, XIA LLC, at its option, will either repair the defective products
without charge for parts and labor, or will provide a replacement in exchange for the
defective product.
In order to obtain service underthis warranty, Customer must notify XIA LLC of the defect
before the expiration of the warranty period and make suitable arrangements for the
performance of the service.
This warranty shall not apply to any defect, failure or damage caused by improper uses or
inadequate care. XIA LLC shall not be obligated to furnish service under this warranty a)
to repair damage resulting from attempts by personnel other than XIA LLC representatives
to repair or service the product; or b) to repair damage resulting from improper use or
connection to incompatible equipment.
THIS WARRANTY IS GIVEN BY XIA LLC WITH RESPECT TO THIS PRODUCT IN
LIEU OF ANY OTHER WARRANTIES, EXPRESSED OR IMPLIED. XIA LLC AND
ITS VENDORS DISCLAIM ANY IMPLIED WARRANTIES OF
MERCHANTABILITYOR FITNESS FOR A PARTICULAR PURPOSE. XIA’S
RESPONSIBILITY TO REPAIR OR REPLACE DEFECTIVE PRODUCTS IS THE
SOLE AND EXCLUSIVE REMEDY PROVIDED TO THE CUSTOMER FOR BREACH
OF THIS WARRANTY. XIA LLC AND ITS VENDORS WILL NOT BE LIABLE FOR
ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
IRRESPECTIVE OF WHETHER XIA LLC OR THE VENDOR HAS ADVANCE
NOTICE OF THE POSSIBILITY OF SUCH DAMAGES.
Contact Information:
XIA LLC
31057 Genstar Rd.
Hayward, CA 94544 USA
Telephone: [phone]
Downloads: http://support.xia.com
Hardware Support: [email protected]
Software Support: [email protected]

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Manual Conventions
The following conventions are used throughout this manual
Convention
Description
Example
»
The » symbol leads you
through nested menu items
and dialog box options.
The sequence
File»Page Setup»Options directs you to pull
down the File menu, select the Page Setup
item, and choose Options from the sub menu.
Bold
Bold text denotes items that
you must select or click on in
the software, such as menu
items, and dialog box options.
...click on the MCA tab.
[Bold]
Bold text within [ ] denotes a
command button.
[Start Run] indicates the command button
labeled Start Run.
monospace
Items in this font denote text
or characters that you enter
from the keyboard, sections
of code, file contents, and
syntax examples.
Setup.exe refers to a file called “setup.exe”
on the host computer.
“window”
Text in quotation refers to
window titles, and quotations
from other sources
“Options” indicates the window accessed via
Tools»Options.
Italics
Italic text denotes a new term
being introduced , or simply
emphasis
peaking time refers to the length of the slow
filter.
...it is important first to set the energy filter Gap
so that SLOWGAP to at least one unit greater
than the preamplifier risetime...
<Key>
<Shift-Alt-
Delete> or
<Ctrl+D>
Angle brackets denote a key
on the keybord (not case
sensitive).
A hyphen or plus between
two or more key names
denotes that the keys should
be pressed simultaneously
(not case sensitive).
<W> indicates the W key
<Ctrl+W> represents holding the control key
while pressing the W key on the keyboard
Bold italic
Warnings and cautionary text.
CAUTION: Improper connections or settings
can result in damage to system components.
CAPITALS
CAPITALS denote DSP
parameter names
SLOWLEN is the length of the slow energy
filter
SMALL CAPS
SMALL CAPS are used for
panels/windows/graphs in the
GUI.
…go to the MCADISPLAY panel and you see…

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1 Introduction
The Pixie-4 Express is designed, among other things, to acquire list mode data from
coincident events in multiple radiation detectors. The methods to set up and acquire such
coincident data, and basic functions to view results, are described in the Pixie-4 Express
User’s Manual. More advanced functions to display coincident events, including the
generation of 2D energy spectra, are provided as a set of add-on procedures to the Pixie
Viewer interface. These functions are described in this document.
1.1 Pixie-4 Express Coincident Energy Plotting Functions
Plotting of Ey vs Ex scatter plots (x,y = channel 0,1,2,3 of the same module)
Histogramming of data into Ey vs Ex 2D histograms
Definition of region of interest (ROI) in the histogram
Extraction of ROI sum and 1D projections
Export as ASCII text and other formats
TDC histograms (offline)
1.2 System Requirements
The advanced energy plotting functions require the Pixie Viewer software (version 4.21 or
higher) and Wavemetrics’ Igor Pro (version 6.22 or higher).
High resolution histograms require significant PC memory and processing power.
1.3 Software Overview
The advanced energy plotting functions are contained in an Igor procedure file (ipf). After
starting the Pixie Viewer as described in the User’s Manual, the procedure file must be
loaded to make use of the functions. See section 2 for details.
The functions operate on list mode data files acquired previously. They can (currently) not
be used for processing during acquisition, but are fully functional in offline mode.
All controls are consolidated in two plots, the 2D SPECTRUM, shown in Figure 4-1 and the
TIME DIFFERENCE panel, shown in Figure 4-3.
1.4 Support
Please read through this manual before contacting us. Contact information is listed in the
first few pages of this manual.

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1.5 Principle of Operation
When trying to measure time and energy of pulses from different detector channels that are
“related” and belong to a common multi-channel event, a fundamental problemis to decide
what is “related”. A seemingly simple approach might be to consider all pulses arriving
within a short coincidence window (CW) as a group and consider them related. However,
this approach becomes difficult if there are multiple pulses within a CW in a single channel
–which of the pulses should be used and/or how to report multiple times and energies per
CW. Furthermore, closely following pulses can create a series of overlapping the CW,
where an individual pulse may belong to several CW records.
In the Pixie-4e, we therefore implemented the concept that an event record is captured for
every detected rising edge. This is the most general case and ensures all possible data is
captured (for example a time stamp and energy value for each pulse). The problem then
becomes one of relating the different records to each other. In the general purpose run type
0x400, each record is for a single channel only, which would require some time sorting
between the channels. In the “group mode” run type 0x402, each record contains data from
all 4 channels. This eliminates the need to sort the channels, and the following discussion
is for data acquired with this run type. The event record includes flags to indicate which
channel actually saw a pulse in the current record (hit). For those channels that did not see
a pulse, previous energies and time stamps are repeated.
From the data of each 4-channel record, one can then compute the time difference between
two channels.
1. If the pulses were truly simultaneous for purposes of data acquisition (i.e. within 1-2
processing clock cycles of 8ns), both channels are flagged as hit, and the time stamp
difference is those 1-2 cycles.
2. If only one channel is hit, the time stamp difference is the time from the hit
channel’s rising edge to the last previous rising edge of the channel that is not hit,
i.e. always looking back in time.
3. If none of the channels is hit, the time stamp difference is from two previous pulses
(the record has been captured based on the trigger from a third channel). This means
the difference repeats and should not be included in any timing histograms. The hit
flags can be used to recognize this case.
4. To compute time difference between two pulses of the same channel, use two
subsequent records –if the time stamp difference is nonzero, it is the time between
two real pulses.
The time differences computed in this way can then be directly be binned into a histogram.
To plot energies, specifically energy sums or related energies from two channels, a CW cut
has to be applied, for example Esum = 0 if Tdiff > CW. Still open is the question on how
to histogram Esum for multiple records within a CW to avoid double counting.

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2 Installation
To install the advanced functions, go through the following steps
Install Igor Pro and the Pixie Viewer software as described in the User’s Manual
Copy the files XIA_E2D.ipf and Pixie_Ecoinc.pxp into the top level folder
of the Pixie software distribution, typically C:/XIA/Pixie4e
Open the Pixie Viewer variant by double clicking Pixie_Ecoinc.pxp
Initialize the variant specific global variables by selecting top menu
XIA » 2D MCA initialize globals
In the PIXIE START UPpanel, click [Start Up System] or [Offline Analysis] to
initialize the software.
Open the 2D SPECTRUM display by selecting top menu XIA » 2D MCA
Open the TIME DIFFERENCE panel by selecting top menu XIA » Timing

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3 Data acquisition settings
For the coincidence energy functions, the data must be acquired in run type 0x402. Please
see section 4.2.1 of the user manual for details. In particular, please remember that the
following options must be enabled in the settings:
oenable group trigger for all channels to record data synchronously
osame trace length and energy filter length for all channels
oMCA binning factor should be 2 or more to ensure the energies are
binned into the 16Ki MCA without being cut off
oenable option for MCA sum histogram
The options of gating, vetoing, accepting out-of-range or piled up pulses apply to the whole
set of 4 channels. So for example, if one out of 4 channels is piled up, nothing is recorded
for any channel unless pileup rejection is turned off for that channel. It is best to disable
pileup rejection and allow out of range events initially.
The coincidence settings can be freely selected: If only real coincidences are of interest,
check only the boxes in the coincidence tab that match the desired hit pattern and set the
Window Width appropriately to the experiment (e.g. accommodating cable delays, time
of flight delays, etc.). The Pixie module will then only record those events. But if file size
and throughput are of no importance, it is equally possible to record all events (Allowed
Hit Patterns = 0xFFFE) and have the offline routines filter out coincidences.
All other settings function as in the standard data acquisition, i.e. ensure gain and offsets
are set properly, decay time tau is correct, etc.

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4 Offline Analysis
The 2D SPECTRUM display is shown in Figure 4-1. Controls in the upper section of the
display are used to select a file and read data from it, to set the display parameters, to open
further plots, and to analyze and export the data. These controls will be described in the
following sections.
Figure 4-1: The 2D SPECTRUM display. Data shown is from a coincidence setup of a HPGe
detector and a NaI detector with a Na-22 source
4.1 File I/O
The name of the file to plot can be entered directly in the Data File control field, or can be
selected in a dialog by clicking on the [Select File] button. These are the same controls as
in the LIST MODE TRACE display of the Pixie Viewer. After selecting the file name, the
[Read File] button must be clicked to extract the energy data from the file and load it into
a local array in Igor.

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4.2 Histogramming Parameters
The data loaded from the file is a list of energies and time stamps. To process this list into
a histogram, first specify the following parameters
1. Define the channels to plot (0..3) and the window (in ns) for which events are considered
coincident.
Note: The coincidence window in the PARAMETER SETUP panel is used for data
acquisition –events further apart than specified are not recorded. The coincidence
window specified here is for plotting recorded events in the 2D energy spectrum.
2. Specify the scaling factor to map the DSP energy range into the histogram bins. The
DSP energy can range from 0 to 65535. To map the full range into the default 256 bins
in each direction, choose a scaling factor of 256 for both x and y. If the measured
energies are less than 65535, decrease the scaling factor to “zoom in” to a certain region
of interest,
3. Specify the offset applied to the DSP energy before scaling. An offset of 0 means energy
0 falls to bin 0 of the histogram, and the maximum energy in the histogram is
65536/scaling factor. If only energies over a certain value should be displayed, enter
that value as the offset. For example, offset 1000 will map the energy rage from 1000
to (65536/scaling factor +1000) to bins 0 to 256.
4. Specify which channel to plot as x and y. Choices are the energies of the first (left) or
second (right) channel specified under 1. or the time difference between them.
As described in section 1.5, only energies of related events are plotted, i.e., the pulses
occurred within the specified coincidence window in the 2 channels. In other words,
plotting of energies in a 2D MCA includes specification of the 2 channels, computation
of the time difference as described above, and then plotting only those events with
Tdiff < CW in the 2D histogram.
After changing any of the parameters, click [Clear/Rescale] to initialize the histogram,
then click [Append] to process the list of energies into the histogram. Additional data files
can be appended into the histogram by selecting the new file(s) and clicking [Append]
without [Clear/Rescale].
For higher resolution data, check the High Resolution box. This changes the number of
bins from 256 x 256 to 4096 x 1024. Display updates may become quite slow on low
performance PCs.
4.3 Additional Plots
There are 3 additional plots and tables to view the data:
Click on [Table] to open a table of the energy lists. Table rows correspond to the event
number in THE LIST MODE TRACE display.
The data in the tableis updated everytime the [Read File] button is clicked. The values
for energy, TrigTime, and LocalTime are as read from the file, no scaling or offset is
1
2
3
4

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applied. The time differences (TdiffA-C) and x/y values to plot (ETx, ETy) are updated
on [Clear/Rescale].
Click on [1D spectra] to open a new plot with projections of the 2D histogram to the
axes.
The data in the plot is updated every time the [Append] button is clicked. The values
are scaled and offset the same as the 2D spectrum.
Click on [Scatter Plot] to open a plot of the entries in the energy list as x vs y (Figure
4-2). The data in the plot is updated every time the [Read File] button is clicked. The
values are as read from the file, no scaling of offset is applied. If the x and y channels
are changed, close and re-open the plot.
Each event is a point in the plot. If the Igor cursor is placed on a point, the information
at the bottom of the plot shows point number, x, and y. The point number matches the
event number in THE LIST MODE TRACE display.
Figure 4-2: Scatter plot of Ey vs Ex and matching event in the LIST MODE TRACE panel
4.4 Analysis and Export
Four buttons allow the following actions:
Click on [Show cursor] to add two cursors to the 2D spectrum plot. The area between
the cursor lines forms the region of interest (ROI)

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Click on [Sum ROI] to sum the counts from all bins inside the ROI. The result is
printed in the Igor command line window (press <ctrl>-j to bring to front)
Click on [ROI Spectra] to open a new plot with the projections of the ROI to the x
and y axis
Click on [Export ASCII] to export the 2D histogramdata and 1D projections to a plain
text file. The file will include header lines and scaling information for the local array
in Igor
Click on [Export IMS] to export the 2D histogram data and 1D projections to a text
file formatted as IMS 2.0 spectrum data.
If the no 0s box is checked, the 2D histogram is reported as a list of bins with position
x, y and counts, omitting bins with zero counts. This is useful to reduce zero data in
high resolution spectra.
4.5 Time Histograms
The TIME DIFFERENCES panel (Figure 4-3) allows to define three time differences
(TdiffA-C), i.e. the channels between which to compute time differences and the binning
parameters of the time histogram. Clicking [Read Timing Data from binary file] will
extract times and energies from the list mode data file
compute the time differences TdiffA, TdiffB, TdiffC for the specified channels (in
nanoseconds)
bins the Tdiffs into histograms with the specified number of bins and bin size.
A table showing energies, event time stamp (TrigTime), local time stamps and the Tdiffs
is opened with the button [Open TS table]. (The table also shows the x and y energy or
time for the 2D histogram.) A plot of the histograms is opened with the button [Display
Tdiff histograms].

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Figure 4-3: The TIME DIFFERENCE panel. Three time differences can be defined between any 2
channels and histogrammed.

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5 Examples
5.1 Delayed Pulser
Figure 5-1: Screenshot from pulser example.
A first example of the functionality is illustrated in the screenshot above. A signal from a
pulser was fed into channel 0 and (delayed) into channel1. Data was acquired in run mode
0x402.
For histogramming, time differences were chosen to be computed between channel 0 and
1 (smaller panel lower right). Clicking “Read Timing Data …”
-Extracts times and energies from the list mode data file
-Computes the time differences TdiffA, TdiffB, TdiffC for the specified channels
(in ns)
-Bins the Tdiffs into histograms with the specified number of bins and bin size.
The results are shown in the TSLIST table and the TDIFFHISTOS plot.
For the 2D histogram, a coincidence window of 100ns was chosen for channel 0 and 1.
Energies from first channel is plotted vs the x axis, energies from the second channel vs

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the y axis. Clicking the button “Read File” does the same 3 steps as above
1
, and also
populates the values for x and y to plot in the 2D histogram (ETx and ETy) IF the time
difference is smaller than the CW.
As an example, consider event #3 shown in the list mode trace display. It was triggered by
ch.1. The hit pattern is 0x0011022F –bit 9 flags ch.1 as hit. This is the delayed channel,
and so ch.0 was captured showing an earlier rising edge. The time stamp for event capture
is 204292 (TrigTime[3] in the table). The local trigger time for ch.1 for this event is 204272
for ch.1 –20 ticks earlier since the trigger distribution takes a few clock cycles. The local
trigger time for ch.0 is 202244, but this corresponds to the earlier rising edge in this
channel; it is repeated from event 2. (Event 2 was captured at 204264, 20 ticks after the
rising edge in ch.0). The time difference between ch.1 (event 3) and the last previous rising
edge in ch.0 (event 2) is thus 204272-202244=28 ticks or 56 ns. Since it is less than the
specified CW of 100ns, ETx and ETy are populated with the energies of ch.0 and ch.1,
respectively. (In event 2, the time difference between the pulse in ch.0 (which triggered
event 2) and ch.1 (which was not hit in event 2) is larger than 100ns and so the ETxy are
set to zero.) Event 3 thus increments a bin at (8785, 8706) in the 2D MCA.
5.2 HPGe and NaI with Na-22 source
A second example is shown in Figure 5-2. The data was acquired using a HPGe and a NaI
detector, with a Na-22 source between them. Prominent lines are at E ~4500 DSP units
(1.2MeV) and E~1800 DSP units (511 keV) for HPGe on the x-axis, and E ~800 DSP units
(511 keV) for NaI on the y-axis. The (511/511) keV coincidence peak is the area with the
highest counts. The acquisition recorded only events where both channels had a hit within
40 ns. The detectors are small, so diagonal lines of constant energies from Compton scatter
between detectors are not visible.
The list of events in the TSLIST table shows events of type 1. and 2. defined in section 1.5:
In event 64, channel 0 and 1 have exactly the same time stamp, and only one event is
recorded. TdiffA=0 and both energy columns have nonzero entries (4053 and 762).
This is an event of type 1.
Note that the TrigTime is 4 ticks later than the local times, as this is the time the
event as a whole registered in the logic.
In event 68, the pulse in channel 1 arrived at local time 18**52 and triggered
acquisition at TrigTime 18**56. For channel 0, the local time shows the timestamp
from the last rising edge at 17**44. Event 68 is thus not in coincidence with a
preceding event and ETx, Ety are zero.
Event 69 however is the pulse from channel 0 at local time 18**64, 12 ticks (24ns)
after event 68. Channel 1’s local time still shows 18**52 and so the time difference
in event 69 to the preceding event is computed to be less than the specified 100ns and
this is a valid event of type 2. ETx = 4285 is the energy reported for channel 0 in
event 69, ETy = 743 is the last valid energy reported before that in channel 1, i.e. the
value from event 68.
2
1
Both “Read File” and “Read Timing Data …” do the same thing
2
Timestamps repeat values from previous events for those channels triggered by another channel, but energies are
set to zero. This is done since “0” is a valid time stamp, but E=0 marks events with no valid energy.

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Figure 5-2: Screenshot from HPGe-NaI example.