The Pixie Hybrid is a multichannel data acquisition system for fast radiation detectors in nuclear physics and other applications requiring coincident radiation detection, and provides the following advantages:
Based on the CompactPCI/PXI standard, the Pixie Hybrid is a 4-channel Digital Pulse Processor used in a variety of nuclear physics applications, including:
Each of the four channels of the Pixie Hybrid accepts signals directly from a detector preamplifier or photomultiplier tube. After a digitally controlled gain and offset state, signals are digitized in a 16 bit ADC at a rate of 250 MHz. 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 32K of spectrum memory per channel, and 256MB of list mode memory organized as a FIFO.
Pixie Hybrid modules can be controlled either by an in-crate single board computer or through a remote PCI or PCIe bridge by a desktop computer. XIA provides a set of C driver functions as well as a graphical user interface, the Pixie-Viewer, based on Wavemetric’s Igor Pro.
Inputs |
Analog | Four preamplifier inputs, switch-selectable input impedance: 50 Ohm or 2 kOhm. Not to exceed +/-1.0V if terminated with 50 Ohms and attenuation is not used. Optional 1/8 attenuation. Works with common resistive feedback preamplifiers of either signal polarity. |
| Digital | Each module has two front panel MMCX connectors for general purpose digital I/O connected to programmable logic.
The Pixie Hybrid connects to the PXI backplane lines, including bussed, nearest neighbor, star and differential star trigger lines. All clock, trigger and synchronization signals are distributed over these lines. |
Data I/O |
Interface | PCI standard |
| Data Transfer Rate | Memory readout to host: ~ 100 MB/s | |
| Transfer Type | Interrupt driven DMA transfers from Pixie Hybrid FIFO memory to host PC memory. FIFO buffer ensures uninterrupted acquisition of detector pulses up to the maximum transfer rate. |
Digital Controls |
Gain | Coarse gain: 2 or 5 course gain setting +/-20% digital gain adjustment for channel matching Pulse amplitudes up to 1.0V (after termination) at gain=2 Proportionally lower at higher gain |
| Offset | DC offset adjustment: -2.5V to +2.5V (before gain) | |
| Trigger | Adjustable trigger filter to suppress noise Filter length: 0.016 to 0.504 μs Threshold range: 4 to 2000 ADC steps (after filter) |
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| Filtering | Trapezoidal filter with peaking times 0.048 to 63.4 μs Adjustable flat top to eliminate ballistic deficit effects |
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| Pileup | Options to reject (default), ignore, exclusively accept piled up pulses which follow too closely to measure pulse heights individually | |
| Coincidence | Programmable coincidence window: 40 to 1016 ns Reject unwanted hit patterns of the 4 channels |
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| Data collection | MCA limits and number of bins Waveform lengths and pre-trigger delay |
Data Outputs |
MCA | 1024 to 32,768 channels (32 bits deep) per Pixie channel Additional memory for sum or 2D spectra |
| List Mode | Time stamp, energy, optional waveforms for each event buffered in 256MB FIFO. | |
| Timing | Events are time stamped with ADC clock in list mode. | |
| Statistics | Livetime, runtime, input rate, output rate, filter dead time | |
| Diagnostics | ADC trace, baseline distribution, baseline history, FFT noise spectrum |
Digital nuclear spectroscopy with pulse shape analysis
Digital X-ray spectroscopy, ultra-high rate
Ultra-low Background Alpha Counters
Differential Pumps, PXI Support Products
Contact XIA LLC Home Office
31057 Genstar Rd.
Hayward, CA 94544, USA
+1-510-401-5760
