Influence of active volume on detection efficiency of GaAs neutron detectors

The semi-insulating (SI) GaAs detectors prepared from bulk LEC (Liquid Encapsulated Czochralski) substrate polished down from both sides to 270 μm were tested as detectors of fast neutrons. The HDPE (High Density PolyEthylene) neutron converter layer was applied on the Schottky electrode using PP (PolyPropylene) glue. The influence of the detector active volume (modified via different reverse voltage applied) on the detection efficiency was studied using
²³⁹
Pu-Be source of fast neutrons. The obtained experimental results were in agreement with the simulation predictions carried out using Monte Carlo radiation transport computer code MCNPX (Monte Carlo N-Particle eXtended).