Measurement and simulation of the response to fast neutrons of VPE GaAs detectors with polyethylene converter

The response of VPE GaAs detectors with a polyethylene converter under fast neutron irradiation from a 241 Am-Be source was measured and simulated. The detection efficiency experimentally obtained was 1.30 · 10 −3 puls./neutr. The simulation of the detector characteristics has showed a good agreement with the experimental data and allowed to estimate the maximum theoretical efficiency of polyethylene converter (1.37 · 10 −3 puls./neutr.). The simulation of the detector response depending on the polyethylene converter thickness and the active layer thickness made it possible to optimize the design of the fast neutron detector. On the basis of the obtained results the following design of the fast can be chosen: the polyethylene converter thickness is 700 μm, the active GaAs layer thickness is in the range from 20 to 30 μm.