Development of neutron shields for gamma-ray detectors

The importance of shields for suppressing neutron-induced background in new classes of gamma-ray detectors such as CZT has been emphasized for a variety of reasons. These include high cross-sections for neutron interactions in detector materials and inefficienct vetoing of neutrons in conventional active shields. We previously demonstrated through Monte-Carlo simulations how our new approach, supershields, is superior to the monolithic, biatomic neutron shields which have been developed in the past. Here we show the construction of several prototype models for supershields using B and H. We verify the performance of these supershields through lab experiments using radioactive sources and monoenergetic neutron beam at the Radiological Research Accelerator Facility(RARAF*), and compare the results with monolithic neutron shields. We also discuss the implications of this experiment for designs of supershields in general.