Advancements in microstructured semiconductor neutron detector (MSND)-based instruments

Microstructured semiconductor neutron detectors (MSNDs) represent a compact, low-cost, high-efficiency means of solid-state thermal neutron detection. Trenches are etched into a 1-cm
²
or 4-cm
²
active area pn-junction diode and backfilled with
⁶
LiF neutron converting material. Charged-particle reaction products produced from neutron capture within the conversion material can be measured to indicate the presence of neutrons. MSNDs can be arranged into larger instruments due to their small size, high-efficiency, and low power consumption. A small, inexpensive electronics package named the ‘Domino’ was developed to facilitate the deployment of the MSND™ technology. The Domino is a complete electronics package that supports a single MSND™ with all necessary signal processing electronics. The Domino electronics were tiled together to form large-area arrays and portable detector arrays. Both were characterized with a small
²⁵²
Cf source. A hand-held portable ‘Briefcase’ detector with 84 Dominoes™, forming a 30 cm × 38 cm array, weighed 21 lbs. A vehicle-portable ‘Panel Array’ detector with 480 Dominoes formed a 1 m × 1 m. For a bare
²⁵²
Cf source, the ‘Briefcase’ detector and the ‘Panel Array’ detector yielded 0.27 ± 0.01 cps ng
⁻¹
(at 2 m) and 0.45 ± 0.01 cps ng
⁻¹
(at 5 m), respectively. Modified Domino packages (with upgraded MSNDs) were arranged into a 2-in. diameter, 6-in. long cylindrical form factor (HeRep Mk II) for direct
³
He replacement, matching the efficiency of a 4-atm
³
He with similar dimensions. A third generation helium replacement (HeRep Mk III) was constructed to replace more compact
³
He form factors, with a 0.75-in. diameter and 4.5-in. length. Populated with dual-sided MSNDs, this detector yielded 0.293 ± 0.003 cps ng
⁻¹
for bare
²⁵²
Cf at 0.2 m.