Mechanical Design and Fabrication of Compact, Portable Nuclear Particle Detectors

Over the past decade there has been an increased interest in compact, portable particle detectors for a variety of applications – nonproliferation, nuclear waste management, fundamental physics research, etc. As a result, many institutions are now designing and building various radiation detectors that can be transported by two or fewer persons or a small vehicle. Historically, neutrino (e.g., Super-Kamiokande experiment in Japan) and neutron detectors have been very large and immobile. These large, static detectors have a substantial volume of passive scintillator, and in the case of neutrino detectors, are buried far beneath the ground surface, minimizing the effects of background radiation. The transition to a compact, portable detector has introduced several challenges in various focus areas. Less scintillator volume means a lower interaction rate requiring more efficient detection techniques and more powerful digitization capabilities. For these reasons, readout components with very high quantum efficiency per unit area and compact, fast-timing electronics with a high-channel count are desirable. The reduction of passive scintillator volume also requires other physical aspects of the detector be cleverly designed and precisely fabricated. Furthermore, these compactness and portability requirements introduce challenges with regard to power and thermal management as well as background radiation discrimination. This paper examines on the mechanical design and fabrication process of compact detector components intended to optimize the optical characteristics of a neutron detector. It focuses on our current optically segmented neutron double scatter camera design, but also reviews lessons learned from our previous compact detector designs, including miniTimeCube and NuLat.