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DGF Pixie-16
16-Channel 100/250/500 MHz Digital Gamma Finder in PXI format

DGF Pixie-16 - Datasheet
(PDF format, 1.35MB, April 2015)

The DGF Pixie-16 is a 16-channel data acquisition system for nuclear physics and other applications requiring coincident radiation detection with large number of channels. It provides digital spectrometry and waveform acquisition for 16 input signals per module; several modules can be combined into a larger system. The DGF Pixie-16 is based on the CompactPCI/PXI standard which allows data transfer rates from Pixie-16 memory to the host computer of up to 109MByte/s. Commercial PXI/CompactPCI modules - DSP processor boards, HV supplies, embedded host computers - can be added to build a flexible standalone data acquisition and analysis system.

Each channel of the Pixie-16 accepts signals from virtually any radiation detector that has an exponential decay output. Incoming signals are digitized with 12 or 14 or 16-bit, 100 or 250 or 500 MSPS ADCs. Digitally controlled offsets can be individually adjusted for each channel. While the voltage gain is fixed to a factory set value, there are two software selectable attenuation factors as well as jumper selectable 50 Ω input termination. Triggering, pile-up inspection and filtering of the data stream is performed in real time; pulse heights and other event data is calculated on an event-by event basis. Results are stored in 512K of spectrum memory and 128K of list mode FIFO memory.

The Pixie-16 module(s) can be controlled either by an in-crate CompactPCI/PXI embedded computer or through a CompactPCI/PXI bridge by a desktop computer. The Pixie-16 is operated through a simple graphical user interface running on Windows. A C driver library, compatible with Linux, is provided for users who plan to integrate Pixie-16 modules into a custom data acquisition system.

The Pixie-16 is operated in a custom made 6U CompactPCI/PXI chassis with high current power supplies. The lower half of the chassis backplane provides a PCI data interface compatible with the 3U CompactPCI/PXI standard. The upper half of the backplane provides high current power connections and more than 150 lines for clock, trigger and data distribution between modules.

The Pixie-16 Software page contains information about Pixie-16 software.

The Pixie-16 Download page contains links to Datasheets, Manuals, Application Notes and Articles.

Click here for details about purchasing the Pixie-16.


Pixie-16 Software

Host software and drivers for the Pixie-16.

Pixie-16 Downloads

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

PXI Support Products

PXI crates, interface modules, power supplies.

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

NEW Pixie-Net

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

NEW Pixie-32

32-Channel Low Cost PXI Express Digital Processor

Pixie-4 Express

125-500 MHz Multichannel DGF in PXIe format


  • 12-16 bit, 100-500 MSPS digitizing of input signal
  • 32bit/33MHz PCI interface with module-to-host transfer rates up to 109MB/s
  • Simultaneous amplitude measurement and pulse shape analysis for each channel
  • Pulse heights measured with up to 16 bits accuracy on each of the four channels
  • Waveform acquisition up to 163us for each channel, in 10 or 4 or 2 ns intervals
  • 32K x 32bit on-board spectrum memory for each channel
  • 128K x 16bit additional on-board FIFO memory for continuous readout of list mode data
  • Fixed gain, adjustable input offset, trigger and energy filter parameters
  • Coincident data acquisition across channels and modules
  • Triggers, run synchronization and clocks distributed over PXI backplane
  • Graphical user interface and C-based driver libraries
  • Operated through in-crate single board PC or through bridge from desktop
  • Can be combined with commercial CompactPCI/PXI processor, power, and computer modules
  • Mixed Pixie-16 variant (12-16 bit, 100-500 MSPS) systems with different detector types


The Pixie-16 can be operated through XIA's host control software or by integrating C libraries into existing user acquisition software. Users can set all parameters relevant to the data acquisition, store them in settings files, and run the modules. Results can be displayed from data files to provide instant feedback on the state of the experiment.

XIA’s host control software provides several diagnostic tools for setting up a new system. There is an oscilloscope display of untriggered waveforms as they are seen by the Pixie module. The waveforms can also be subjected to a fast Fourier transformation (FFT). These displays are useful to investigate if there is any electromagnetic interference in the system, from 50/60Hz to radio-frequency pickup. For system setup, users can employ automated tools to determine the decay time of the preamplifier and to set the offset to a specified fraction of the dynamic range.

Experimenters who run their own data acquisition software can use XIA’s driver (written in C) to integrate Pixie modules into their system. Module setup, start and stop of runs, and data readout can be performed using a small number of functions. The Pixie Viewer is based on the same driver and can be used as a programming example.

Pixie-16 Data Acquisition Systems

A basic data acquisition system can consist of a 14-slot Pixie-16 crate with integrated preamp power supplies, one Pixie-16 module, a single board host computer and a high voltage module. The host computer is used to download software and settings to the Pixie module, start and stop runs, read out the data and write it to disk.

Instead of a single board computer residing in the PXI crate, a regular desktop or laptop computer can act as a remote crate controller using a set of adapter cards with a high speed copper or fiber optic data link. Data readout speeds are equivalent for local and remote controllers.

For bigger detector arrays, one or more slots can be occupied by commercial, user-programmable DSP processor modules to process data for event reconstruction. High speed I/O modules can be added, either on the DSP modules or in a separate slot, for fast data readout from the Pixie front end electronics to external data processing computers.


Inputs Analog Sixteen preamplifier inputs, switchable input impedance and attenuation:
50 Ω or 1 kΩ or 4 kΩ (or according to user specification)
Full scale range +/-2V (Not to exceed +/-3.5V if terminated with 50 Ohms and attenuation is not used)
Works with common resistive feedback preamplifiers of either signal polarity
  Digital 28 digital inputs/ouputs, including:
4 high speed LVDS input/output connections
16 LVDS inputs for channel specific gating
LVTTL inputs and outputs for general purpose Option for external clock through front panel input. In addition, there are more than 160 digital lines on the backplane for low skew system clock distribution, trigger, run synchronization, and global veto lines, and complex trigger logic, multiplicity information, or data transfers between modules.
Data I/O Interface Compact PCI/PXI standard, 33 MHz, 32-bit

Data Transfer Rate Memory readout to host: 109 MByte/sec
Digital Controls Gain Fixed voltage gain set to user specification, digital gain adjustement +/- 10%.
  Offset -1.5V to +1.5V in 65536 steps

Filtering Rise time and flat top: 0.02 to 80 us in small steps
Adjustable flat top to eliminate ballistic deficit effects
  Pileup Fast channel filter time, pulse detection threshold, and fast channel pileup inspection test limits may be set independently to achieve best results in every gamma-ray energy regime
  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 Time stamp (48-bit), energy, optional waveforms and QDC sums for each event stored in 128K (16-bit) FIFO for uninterrupted data acquisition
  Timing Events are time stamped with 100 or 125 MHz clock in list mode with fractional constant fraction discriminator (CFD) time that is captured at full ADC clock rate (100 or 250 or 500 MHz)
  Statistics All values required for pileup correction are available: livetime, realtime, input events, output events
  Diagnostics ADC trace, baseline distribution, baseline history, FFT noise spectrum

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http://www.xia.com/DGF_Pixie-16.html, last updated November 30, 2017
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