Low Cost, Large Volume 3He Replacement Neutron Detector

Nuclear instrumentation for the detection of thermal neutrons relies heavily upon 3He because of its desirable nuclear properties and physical characteristics. The decline in production combined with increased demand has depleted the 3He stockpile and the supply of 3He is presently insufficient for US needs. The proposed effort seeks to address this problem by developing detector technology to help replace the existing generation of 3He-based instrumentation with detectors that use other neutron-sensitive material such as lithium. The Phase I prototype will comprise multiple sandwiched layers of converter/scintillator pairs connected to readout pulse processing electronics. Completion of the prototype and testing will demonstrate a path to attain at least 50 percent thermal neutron detection efficiency and gamma ray rejection rates of at least 10-5. The detectors will be designed to match the performance specification of existing 3He detectors in terms of overall neutron detection efficiency and gamma-ray rejection. Moreover, the instruments can be inexpensively scaled to cover large surface areas to be applied in both neutron scattering research as well as homeland security screening applications. Large detectors are most critical for advancement in these areas and face the greatest risk of cancellation or curtailment due to the shortage of 3He.