Thin-film-coated bulk GaAs detectors for thermal and fast neutron measurements

GaAs-based structures are presently under investigation as the substrate fo r B-10-coated and polyethylene-coated neutron detectors. The semi-insulatin g (SI) GaAs-based devices operate at low bias voltages by employing the tru ncated electric field effect, which allows for acceptable signals to be pro duced with bias voltages ranging between 10 and 50 V. At this time, the B-1 0-coated devices have demonstrated over 3.5% intrinsic thermal neutron dete ction efficiency with reactive films 1.8 mum thick. Relatively high neutron /gamma -ray rejection ratios can be achieved with an appropriate choice of lower level discriminator setting. Polyethylene-coated GaAs devices are bei ng studied as fast neutron detectors and have shown evidence of (n,p) react ions for 14MeV neutrons. Theoretical neutron responses and experimental neu tron detection data are presented and compared. (C) 2001 Elsevier Science B .V. All rights reserved.