Year
2010
Abstract
Efficient, robust neutron detection systems are paramount in nuclear safeguards and nonproliferation applications. Nearly all commercially applied neutron counting systems employ 3He gas for the detection of thermal neutrons. These systems provide high neutron detection efficiency while being almost completely insensitive to gamma rays. However, due to the large number of such systems deployed in the field, there is currently a shortage of 3He gas. Therefore, novel neutron detection systems are needed. In order to be competitive with 3He, these systems should preserve the incoming neutron energy information while maintaining high detection efficiency and allowing neutron/gamma ray discrimination. One class of detectors that has been recently explored is capture-gated scintillation detectors which consist of a standard scintillation detector that has been modified to include a neutron capturing isotope. Here, a novel detector is described consisting of slabs of commercial plastic scintillator separated by thin foils of cadmium metal. The combined signal generated by multiple (n, p) collisions in the plastic scintillator is a measure of the incident neutron kinetic energy if the neutron deposits all of its energy within the detector body. Low-energy neutrons that remain in the detector may be captured in the cadmium sheets (the thermal-neutron cross section is approximately 2,500 b for natural cadmium). A total of 9 MeV of gamma-ray energy is released upon capture and these gamma rays will provide a large scintillation pulse. Simulations of this detector will be performed using the MCNP-PoliMi code. A prototype of this detector has been constructed recently. In this paper, both simulated and measured results are presented.