Pixie-16

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.

It can be used in a variety of applications including:

• Segmented HPGe detectors
• Silicon Strip detectors
• Scintillation detector arrays
• Synchronous waveform capture for gamma-ray tracking
• Sub-nanosecond timing measurements
• Fast coincidence gamma-ray spectroscopy