Advanced multilayer composite structures for fast neutron detection and shielding protection applications

Abstract A new type of multilayer composite heavy-oxide scintillator detector (named “ZEBRA”) was developed and characterized for fast neutron detection for homeland security and nuclear safeguards applications. In this heterogeneous detector medium, composite layers, comprising microgranules of heavy-oxide scintillators [CdWO4 (CWO), ZnWO4 (ZWO), PbWO4 (PWO), Bi4Ge3O12 (BGO), Gd2SiO5(Ce) (GSO(Ce)), and some others] dispersed in transparent plastic, are alternated with layers of clear plastic that serve as scintillation light guides and as a neutron moderator material. The efficiency and sensitivity of ZEBRA-detectors compare favorably with those of detectors based on large-size single crystals, but the composite ZEBRA structures are much less expensive and can be manufactured in much larger dimensions. These composite detectors represent a significant advancement from earlier single-crystal detector types and are the result of recent efforts to explore alternatives and improvements to conventional 3He counters. The high detection efficiency of ZEBRA detectors is due to both substantial energy reduction from processes such as elastic scattering, and the subsequent resonant absorption of moderated fast neutrons. Therefore, similar multilayer composite ZEBRA structures can also be considered as new shielding materials for protection against fast neutrons.