Application of Pixel-Cell Detector Technology for Advanced Neutron Beam Monitors

Currently available neutron detectors are limited in their ability to be used with the intense neutron beams used for the advanced study of materials at large-scale national facilities. A large number of neutron-scattering experiments require beam monitors to operate in an intense neutron beam flux of more than107 neutrons per second per square centimeter. For instance, a 4 cm x 4 cm intense beam flux of 6.25x107 n/s/cm2 at the Spallation Neutron Source will put a flux of 1.00x109 n/s at the beam monitor. Currently available beam monitors will need to be replaced in less than two years of operation due to wire and gas degradation issues. There is also a need for beam position information that is beyond the capabilities of currently available 3He and BF3 neutron beam monitors. This project will investigate the use of pixel-cell technology for developing a new generation of stable, high-count-rate neutron beam monitors and position-sensitive detectors. In Phase I, a prototypical 2 x 4 Pixel-Cell Neutron Beam monitor was conceptualized, designed, and constructed. The prototype unit was successfully tested and evaluated in a neutron beam at the High Flux Isotope Reactor in Oak Ridge. In Phase II, the pixel cell technology will be tested further with the prototype beam monitor, leading to refinement and optimization of the technology. Using these refinements, a two-dimensional pixel-cell area detector will be designed and built for testing at a neutron beam source. Commercial Applications and Other Benefits as described by the awardee: The technology should lead to the development and commercialization of advanced neutron beam detectors that would directly benefit the Spallation Neutron Source and other intense neutron sources such as the High Flux Isotope Reactor. Advancing the detector capabilities is equivalent to increasing operational efficiency and reducing the experiment beam time at these facilities, which, in turn, results in important savings in operation cost and increased experimental output.