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2-8 Channel, 125-500 MHz Desktop Digital Processor

Pixie-Net - Datasheet
(PDF format, 512kB, April 2018)

The Pixie-Net is a multi-channel digital spectrometer for radiation detectors in desktop format with integrated networking and USB resources. Designed for high-precision coincidence gamma-ray spectroscopy using HPGe detectors, scintillators, or silicon detectors, the Pixie-Net offers not only detector signal digitization and waveform capture but also pulse height measurements, on-board energy histograms, time stamping and constant fraction timing, pileup inspection, external gating and online pulse shape analysis. Besides nuclear spectroscopy, the Pixie-Net can be used for neutron/gamma discrimination, time-of-flight measurements, and coincidence/anti-coincidence measurements.

The Pixie-Net combines an embedded Linux system with XIA’s digital pulse processing developed on the Pixie PXI/PXIe spectrometer series. Incoming signals are digitized at 125-500 MSPS with 12-16 bit ADCs, depending on the variant purchased. Using a ZYNQ All Programmable SoC with programmable logic (FPGA) and a dual-core ARM® processor on the same chip, the ADC data stream is captured and processed in the FPGA section and the ARM processor writes the results to a local SD card or USB drive, or makes them available on a web server. Multiple units can share signals though GPIO.

The Pixie-Net Software page contains information about Pixie Viewer software, which is used to operate the Pixie-4e.

The Pixie-Net Download page contains links to Datasheets, Manuals, Application Notes and Articles.

Click here for details about purchasing the Pixie-4e.


Pixie-Net Software

Host software and drivers for the Pixie-4 and Pixie-500.

Pixie-Net Downloads

Datasheets, Manuals, Application Notes and Articles, as well as downloadable software and firmware.

Pulse Shape Analysis with the Pixie-Net

Micro-power, credit-card-sized DGF for portable applications.

Pixie-4 Express

125-500 MHz Multichannel DGF in PXIe format


  • Compact standalone detector readout electronics.
  • 2-8 channels, 12-16 bit, 125-500 MSPS pulse processor.
  • 32K on-board MCA spectrum per channel.
  • Waveform capture and Pulse Shape Analysis.
  • Sub-nanosec Timing Resolution.
  • Embedded Linux platform (based on Ubuntu 12.04 LTS)
  • Front and back panel digital I/O signals.
  • Gbit Ethernet
  • Local data storage on removable USB drive or SD card
  • 1 GB processor memory
  • Web interface
  • No PC required for setup and operation
  • Open source C/C++ data acquisition software
  • Approx. 8x8x14cm, 1 kg, 18 W
  • Low cost


The Pixie-Net runs a customized version of Ubuntu 12.04 LTS “in the box”. Many applications from the Linux universe are installed (gcc, ftp, http, ssh, SMB, etc), more can be added by the user. A number of simple C/C++ programs read results and waveforms from the FPGA section, format and store them to file, and make them available on a web server. Settings and results can be managed through a web interface provided by XIA, or with plug-ins for common acquisition/analysis tools (e.g. LabVIEW, MATLAB, Igor Pro). All parameters can be saved to file for easy switching between applications.

The Pixie-Net is a standalone data acquisition system, eliminating the need for a host PC and software drivers to control and readout a USB or PXI peripheral. Data acquisition can be set up, started/stopped, and monitored over the network, with data saved to local storage or shared over the network.

Options for operation include:

  • Remote login to the embedded Linux system via a basic terminal program
  • Monitor MCA spectra and run statistics via a web page hosted by the Pixie-Net Linux system
  • Save data to mounted network drive or local USB drive
  • Download MCA spectra, run statistics, and list mode
    data files from web server
  • Integrate web API into front end GUI built on analysis software

Multiple Pixie-Net units can be assembled as a distributed data acquisition system, each Pixie-Net collecting locally, yet synchronized over the network. Hardware support for IEEE 1588 clock synchronization is included in the Zynq SoC, allowing sub-microsecond synchronization of multiple devices.


Front-Panel I/O Signal Input 2-8 analog SMA inputs with:
Programmable input impedance: 50 Ohm or 10 kOhm
After termination and attenuation, up to ±1.25V DC can be added to compensate signal DC offsets
After DC offset compensation, signals in the range from 0V to (2V/analog gain) are accepted by the ADC. (See below for analog gain values)
  Pulser Output 1 MMCX coaxial connector with:
Periodic, exponentially decaying reference pulser.
Programmable on/off
  Control Voltage Output 1 MMCX coaxial connector with:
0-5V programmable control voltage via DAC (e.g. for HV control)
Rear Panel I/O Logic

General Purpose I/O connected to programmable logic:

1 MMCX coaxial connector
   input only
   default use: Veto signal to suppress event triggering
   2.5V logic, 5V compatible

1 micro HDMI connector with 13 GPIO signals (not video)
   single ended or differential
   can be used as clock input
   factory set to 5V (default) or 2.5V logic. 

12V DC in.
AC adapter requirements: 12V, 18W, Barrel Plug 2.1mm I.D. x 5.5mm O.D., center positive
5V DC out
MMCX coaxial connector

Usage: typical ~10W, peak ~14W
  PMOD 12-pin 0.1” connector for 8 I/O signals, 3.3V power, GND
Compatible with PMOD I/O modules (I2C, GPIO, serial, wifi, GPS, …)
Embedded Processing Processor

Xilinx Zynq

  Data Interfaces

10/100/1000 Ethernet
USB 2.0 (host)


128 Mb of QSPI Flash
16 GB micro SD card (removable)

  Operating System

Linux (Xillinux – based on Ubuntu LTS 12.04)
Operates from Linux partition on SD card

Digital Controls Gain

Coarse gain:
  250 MSPS variant: 2 gain settings: 2 and 5
  Other variants: please contact XIA
Digital gain:
  Arbitrary gain factor for channel matching

  Offset DC offset adjustment from –1.25V to +1.25V, in 65535 steps.

Trapezoidal filter with peaking times 0.048 to 63.4 us
Adjustable flat top to eliminate ballistic deficit effects

  Trigger Digital trapezoidal trigger filter with adjustable threshold. Rise time and flat top set independently.

Programmable coincidence window: 40 to 1016 ns
Reject unwanted hit patterns of the 4 channels

  Data collection

MCA number of bins
Waveform lengths and pre-trigger delay
List mode data format (text, binary, content)

Data Outputs MCA

1024-32768 bins per channel, 32 bit deep (4.2 billion counts/bin).
Additional memory for sum spectrum for clover detectors.

  Statistics Real time, counting time, filter dead time, input and throughput counts.
  List Mode

Pulse height (energy), time stamps, pulse shape analysis results, waveform data (up to 4Ki samples) and ancillary data like hit patterns.

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http://www.xia.com/Pixie-Net.html, last updated June 22, 2018
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