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DGF Pixie-32
32-Channel Low Cost PXI Express Digital Processor

Pixie-32 Datasheet
(PDF format, 320KB, April 2018)

Taking advantage of new low cost, high density ADC components, this new member of XIA's Pixie spectrometer family is designed to address needs in the nuclear physics community for instrumenting large scale radiation detectors at relatively low cost. The Pixie-32 is a true multi-channel spectrometer that not only digitally captures incoming waveforms but also provides good time and energy resolution at a per channel cost up to 10 times lower than other digital readout modules of similar capability.

The Pixie-32 is the first member of a family of digital spectrometers modules that will all share the same communication back-end while their front-ends have a variety of digitization and signal processing options to meet the community's broad spectrum of readout electronics needs. This approach enhances the instrument's flexibility because the front-end is easily adaptable to different experiments or applications.

The Pixie-32 is a 3U PXI Express (PXIe) card housed in a PXIe chassis. Its front panel high density connector can accept up to 32 single-ended analog signals. An optional 32 channel mezzanine board is under development that will expand the Pixie-32's capacity to 64-channels. Output data transfer is via PCI express which, with suitable PC configuration, supports reading out multiple modules in parallel. Integration into larger systems is facilitated by front and back panel digital I/O that allow the Pixie-32 to generate and respond to various clock, trigger and veto signals.


PXI Support Products

PXI crates, interface modules, power supplies.


16 integrated DGF channels on a single-width 6U PXI card

Pixie-4 Express

125-500 MHz Multichannel DGF in PXIe format

NEW Pixie-Net

Four integrated DGF channels on a single-width PXI card


  • 32 channel 12 bit 65 MSPS pulse processor
  • Synchronous multi-channel waveforms acquisition
  • Processor peaking times adjustable from 0.08 - 162 Ás
  • Pile-up inspector and run statistics counters
  • Sub-nanosecond timing resolution
  • PXI Express platform: x4 link
  • Front and back panel digital I/O signals
  • Coming soon: on-board energy histogramming and pulse shape analysis parameters


  • HPGe detector arrays
  • Scintillator detector arrays
  • Silicon detector arrays
  • Gas counters
  • Real-time pulse-shape discrimination
  • Waveform analysis
  • Time dependent spectroscopy


The Pixie-32 is operated through XIA's graphical user interface OmmniVore. All interfaces call functions from the same C driver library, which handles conversion of physical parameters (e.g. filter times) into numbers used by the firmware. All parameters can be saved to disk for easy reloading at boot time.

The C library is largely compatible with Linux and code is available to users who plan to integrate Pixie-32 modules into a custom data acquisition system. All host software is provided as open source. Users can also add their own functions to the DSP events processing code.


Inputs Analog 32 or 64 preamplifier inputs, switchable input impedance:
50 Ω or 1 kΩ (or according to user specification)
Works with common resistive feedback preamplifiers of either signal polarity
  Digital 10 digital inputs / ouputs for triggers or veto signals.
(Also configurable as 5 high speed differential signals.)
Backplane I/O Clock Low skew system clock distributed to all modules

Digital Configurable LVTTL and LVDS lines for veto, run synchronization, multiplicity, and trigger distribution
PXI Express Interface 3U CompactPCI form factor with x4 PCI Express interface

Data Transfer Rate Memory readout to host: 400 MByte/sec (sustained)
Parallel readout of modules with suitable chassis and PC
(e.g. a x16 host PC can read 4 modules in parallel)
Digital Controls Gain On-board variable gain amplifier for flexible gain selection, +/- 10% digital adjustment
  Offset -1.25 V to 1.25 V in 16384 steps by channel

Energy Filter Rise time and flat top: 0.08 - 162 µs
  Acquisition Local and shared trigger, hit pattern, coincidence window
  Data collection MCA limits and number of bins, waveform lengths
Data Outputs MCA 1024 to 32,768 channels (32 bits deep) per Pixie channel
  List Mode Energies, timestamps and waveforms
  Statistics All values required for pileup correction are available: livetime, realtime, input events, output events
  Diagnostics ADC trace, baseline distribution, baseline history

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http://www.xia.com/DGF_Pixie-32.html, last updated June 22, 2018
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