Thermal and Fast Neutron Multiplicity Counter

Neutron multiplicity can provide effective detection and identification of shielded Special Nuclear Materials (SNM) based on analysis of the time correlated neutron multiplicity distribution. RMD is developing a composite detector, consisting of Cs2LiYCl6:Ce (CLYC) scintillator incorporated into dual-mode plastics, which provides an ideal solution for this task. CLYC offers (1) efficient thermal neutron detection - about 6 times higher than He-3 at 3 atmospheres) and (2) excellent separation between gamma and neutron particles (>10-7). Dual mode plastic scintillator, used as a matrix / moderator in the composite detector, offers high fast neutron detection efficiency and good gamma-neutron discrimination. Together, the CLYC scintillator incorporated in a dual-mode plastic scintillator / moderator will be a building block, which can be combined in variety of numbers and geometries to build versatile neutron detection systems. The goal of the effort will be to build an array, which reproduces the thermal neutron multiplicity performance of MC-15, developed by our collaborators from LLNL. In addition the system will provide fast neutron multiplicity counting. The proposed modular approach is very powerful to achieve optimal size of the system which will meet and surpass the requirement for efficiency, while maintaining low power, complexity, weight and cost.