The Pixie-Net is a multi-channel digital spectrometer for radiation detectors in desktop format with integrated processor, networking and USB resources. No PC is required for operation. Advantages include:

  • Compact desktop or OEM card formats
  • Embedded processor with Linux OS, – no PC required
  • Web Server interface for remote operation
  • High Performance specification: 250 MSPS at 12-bit resolution
  • Optional IEEE 1588 PTP time synchronization over network




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. Applications include:

  • High resolution Gamma Spectroscopy
  • Coincidence / anti-coincidence spectroscopy
  • Neutron/Gamma Discrimination
  • Waveform capture and analysis
  • Time of Flight and other precision timing measurements
  • Networked distributed detector systems
  • Precision Timing Protocol and Network Synchronization

More about Applications…


Technical Data

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 250 MSPS with 12-bit ADCs.  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.


  • Compact standalone detector readout electronics.
  • 4 channels, 12-bit, 250 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 15)
  • 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
  • Optional IEEE 1588 PTP time synchronization over network
  • Approx. 8x8x14cm, 1 kg, 18 W
  • Low cost


Front-Panel I/O

Signal Input 4 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 or PTP Ethernet port
factory set to 5V (default) or 2.5V logic.

Power 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 connectorUsage: 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)
Memory 1 GB of DDR3 SDRAM
128 Mb of QSPI Flash
16 GB micro SD card (removable)
Operating System Linux (Ubuntu 15)
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.
Filtering Trapezoidal filter with peaking times 0.048 to 63.4 μs
Adjustable flat top to eliminate ballistic deficit effects
Trigger Digital trapezoidal trigger filter with adjustable threshold. Rise time and flat top set independently.
Coincidence 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.
Timing Events are time stamped with ADC clock in List Mode.
Optional online constant fraction timing
Pulse Shape Analysis Optional general purpose pulse shape analysis.
Can discriminate gammas/neutrons, betas/gammas etc insuitable detectors.
List Mode Pulse height (energy), time stamps, pulse shape analysis results, waveform data (up to 4Ki samples) and ancillary data like hit patterns.