Development of compact high efficiency microstructured semiconductor neutron detectors

Abstract

Semiconductor diode detectors coated with neutron reactive materials are generally fashioned as planar diodes coated with 10 B, 6 LiF, or Gd. Planar detectors coated with 10 B or 6 LiF are limited to less than 5% intrinsic thermal neutron detection efficiency. Detectors coated with Gd can achieve higher efficiencies, but the low-energy signatures are problematic in the presence of background radiations.

Improving Detection Efficiency of Silicon Carbide Neutron Detector Using Double Trench

“…From the previous discussion, it can be seen that 10 B has a higher probability of capturing thermal neutrons but produces lower secondary particle energy [35], so the 10 B-type SiC neutron detector has a smaller structure size parameter [9], [13], [32], [33], [37]. However, 6 LiF has a lower probability of capturing thermal neutrons but produces higher secondary particle energy [35], so the structure size parameter of 6 LiF type SiC neutron detectors is larger [9], [13], [32], [33], [37]. If 10 B is backfilled into a trench with a width of T B , and 6 LiF is backfilled into a trench with a width of T LiF , the properties of 10 B and 6 LiF to react with thermal neutrons can be fully utilized.…”

“…Thus, the output response of the semiconductor neutron detector indirectly realizes the detection of neutrons. Several groups have made substantial early contributions to the development of Si-based neutron detectors [9], [10], [11], [12], [13], [14], [15]. Typically, the thermal neutron intrinsic detection efficiency for thin-film-coated detectors is lower than 5% [6], [10], [16].…”

“…To improve the detection efficiency, researchers have proposed a stacked silicon neutron detector structure [17], [18]. In addition, McGregor's group developed a silicon microstructured semiconductor neutron detector (MSND) that significantly improves the neutron detection efficiency [13], [14], [15], [19], [20].…”

A semiconductor-based neutron detection system for planetary exploration

“…Crystalline density of 6 LiF is 2.55 g cm -3 , however, the method by which the 6 LiF powder is filled into the microcavities, a packing fraction of approximately 35% is achieved. The backfilled trenches are repeated every 30 µm, with the remaining volume filled with Si, as shown in Figure 8 (Shultis and McGregor, 2009;McGregor et al, 2015). Neutrons intersecting the 6 LiF trenches have some probability of absorption by the 6 Li nucleus based on the angle of impact and the neutron absorption cross section for the given energy of the neutron.…”

“…To meet these demands, we have developed a semiconductor-based lowenergy neutron detection system capable of differentiating thermal and epithermal neutrons. The system uses multiple microstructured semiconductor neutron detectors (MSNDs) arranged into a planar-type detector array (McGregor et al 2015;Ochs et al 2018). We experimentally measured the performance of three different configurations of the low-energy neutron detection system for spaceflight application, which resulted in a functioning sensor system prototype that is able to detect and differentiate thermal and epithermal neutrons.…”