Multilayered Solid-State Neutron Sensor

Abstract

Recent advances in semiconductor processing technology have enabled development of a solid-state neutron sensor with exceptional efficiency for its unique reduced size. The boron-10 ( n, alpha) capture reaction is used to detect incident thermal neutrons. This reaction offers significant advantages for a small detector because the reaction products have high energies which can generate a large number of charge carriers in semiconductor materials by impact ionization. The enabling and differentiating technology of the sensor design is a stack consisting of multiple bilayers alternating between converter material (boron) and collector semiconductor material (silicon). As the number of these bilayers increases, the probability of a neutron interacting with boron-10 in at least one of the bilayers-so it is captured in the detector before it has a chance to pass through-approaches unity. The sensor can be made very thin while also remaining highly efficient, offering a unique possibility for low-profile in situ dosimetry. Calculations have shown that a multilayer sensor with an efficiency greater than 70% is feasible in a sensor stack 2 mm thick.