Solid-state thermal neutron detectors are desired to replace 3 He tube tube-based technology for the detection of special nuclear materials.
3He tubes have some issues with stability, sensitivity to microphonics and very recently, a shortage of 3 He. There are numerous solid-state approaches being investigated that utilize various architectures and material combinations. Our approach is based on the combination of high-aspect-ratio silicon PIN pillars, which are 2 µm wide with a 2 µm separation, arranged in a square matrix, and surrounded by 10 B, the neutron converter material. To date, our highest efficiency is ~ 20 % for a pillar height of 26 µm. An efficiency of greater than 50 % is predicted for our device, while maintaining high gamma rejection and low power operation once adequate device scaling is carried out. Estimated required pillar height to meet this goal is ~ 50 µm. The fabrication challenges related to 10 B deposition and etching as well as planarization of the three-dimensional structure is discussed.
Solid state thermal neutron detectors are desirable for replacing the current 3 He based technology, which has some limitations arising from stability, sensitivity to microphonics and the recent shortage of 3 He. Our approach to designing such solid state detectors is based on the combined use of high aspect ratio silicon PIN pillars surrounded by 10 B, the neutron converter material. To date, our highest measured detection efficiency is 20%. An efficiency of greater than 50% is expected while maintaining high gamma rejection, low power operation and fast timing for multiplicity counting for our engineered device architecture. The design of our device structure, progress towards a nine channel system and detector scaling challenges are presented.
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