10/10/19 ASHE Seminar
Malcolm J Joyce Department of Engineering, Lancaster University and Hybrid Instruments Ltd.
TITLE: Positive (neutron!) discrimination
Neutrons are relatively easy to detect when slow (thermalized), due to the extensive prior art associated with 3He-filled ionisation chambers. Helium-3 has the benefits of long-term stability in use and relative immunity to g rays; the latter is important because neutron fields almost always co-exist with an associated g-ray environment. However, fast neutrons have some important characteristics, such as their energy prior to thermalisation, that we often wish to exploit to our advantage. For example, the energy spectrum of fast neutrons in a given environment can provide important information on the adequacy or otherwise of radiation shielding and neutrons detected otherwise unimpeded (i.e., having not undergone an interaction), can provide information as to their origin for location, thus yielding imaging capabilities. Further, the temporal correlation of fast neutrons emitted from correlated phenomena (most often fission) can be used to target such phenomena, specifically, often for the purposes of nuclear safeguards assay. In this seminar, a commercial means by which fast neutrons can be discriminated from g rays digitally and in real-time will be described, and some of the pitfalls and highlights of running a business for > 15 years based on this technology for what can be an extraordinarily esoteric customer base will be described.