Pixie-16 16-channel PXI Digital Pulse Processor for Nuclear Spectroscopy

The Pixie-16 provides digital spectrometry and waveform acquisition for 16 input signals per module; several modules can be combined into a larger system. The 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 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.

• 14-16 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 (14-16 bit, 100-500 MSPS) systems with different detector types