Prototype of a CLYC Based Detector System for Special Nuclear Material Accounting

Accounting for nuclear material is important for nuclear fuel processing, and the He-3 tube has been used extensively for neutron detection in accounting methods. While He-3 tubes are the gold standard, they require high voltages to operate, and the shortage of 3He has driven up their cost; thereby providing an impetus to develop new neutron detectors. An instrument that could replace 3He and provide additional information, such as gamma-ray and neutron spectra, would provide an important tool for nuclear material accountability applications. CLYC (Cs2LiYCl6), a scintillation material that produces a light flash with an intensity proportional to the energy deposited from an ionizing event, has the potential for replacing 3He, while proving gamma and neutron spectroscopy. RMD is fabricating 6Li enriched CLYC, where the 6Li(n,a)t reaction has a large neutron capture cross section, and with a high density of 6Li, the material exhibits a high detection efficiency for neutrons. CLYC provides identification of gammas and neutrons through pulse-shape discrimination, but the light yield from the material produces a long decay tail. This long decay has been observed as one of the major drawbacks for CLYC, as the material will be limited in providing discrimination at very high gamma rates. By observing the behavior of the CLYC light pulse in more detail, we provide a detector prototype that will discriminate gamma and neutrons at gamma ray event rates up to at least 1 MHz