Joyce, Malcolm and Aspinall, Michael and Cave, Frank and Lavietes, Anthony (2014) A 16-channel real-time digital processor for pulse-shape discrimination in multiplicity assay. IEEE Transactions on Nuclear Science, 61 (4). pp. 2222-2227. ISSN 0018-9499
Full text not available from this repository.Abstract
In recent years, real-time neutron/?-ray pulse-shape discrimination has become feasible for use with scintillator-based detectors that respond extremely quickly, on the order of 25 ns in terms of pulse width, and their application to a variety of nuclear material assays has been reported. For the in-situ analysis of nuclear materials, measurements are often based on the multiplicity assessment of spontaneous fission events. An example of this is the 240Pueff assessment stemming from long-established techniques developed for 3He-based neutron coincidence counters when 3He was abundant and cheap. However, such measurements when using scintillator detectors can be plagued by low detection efficiencies and low orders of coincidence (often limited to triples) if the number of detectors in use is similarly limited to 3 or 4. Conversely, an array of > 10 detector modules arranged to optimize efficiency and multiplicity sensitivity, shifts the emphasis in terms of performance requirement to the real-time digital analyzer and, critically, to the scope remaining in the temporal processing window of the firmware in these systems. In this paper we report on the design, development and commissioning of a custom-built, 16-channel real-time pulse-shape discrimination analyzer specified for the materials assay challenge summarized above. The analyzer incorporates 16 dedicated and independent high-voltage supplies along with 16 independent digital processing channels offering pulse-shape discrimination at a rate of 3 × 106 events per second. These functions are configured from a dedicated graphical user interface, and all settings can be adjusted on-the-fly with the analyzer effectively configured one-time-only (where desired) for subsequent plug-and-play connection, for example to a fuel bundle organic scintillation detector array.