Cryogenic neutron detector by InSb semiconductor detector with high-density helium-3 gas converter

The neutron-detection characteristics of a cryogenic neutron detector comprising an InSb semiconductor detector and a helium-3 gas converter were evaluated at a gas pressure up to 12.4 atm at 4.2 K. The detector successfully detected stable neutrons under these conditions, where the density of the helium-3 gas is a few-hundred times higher than that at room temperature. It was found that the neutron detection efficiency was correlated with the gas pressure—even in a backward-detection configuration—in low-temperature, high-pressure helium-3.