Laboratory tests on neutron shields for gamma-ray detectors in space

Shields capable of suppressing neutron-induced background in new classes of gamma-ray detectors such as CdZnTe are becoming important for a variety of reasons. These include a high cross section for neutron interactions in ne w classes of detector materials as well as the inefficient vetoing of neutr on-induced background in conventional active shields. We have previously de monstrated through Monte-Carlo simulations how our new approach, supershiel ds, is superior to the monolithic, bi-atomic neutron shields which have bee n developed in the past. We report here on the first prototype models for s upershields based on boron and hydrogen. We verify the performance of these supershields through laboratory experiments. These experimental results, a s well as measurements of conventional monolithic neutron shields, are show n to be consistent with Monte-Carlo simulations. We discuss the implication s of this experiment for designs of supershields in general and their appli cation to future hard X-ray/gamma-ray experiments. (C) 2000 Elsevier Scienc e B.V. All rights reserved.