Neutron Detector System Using Cross Fiber Scintillator Readout

75320B New types of neutron detector technologies are required for the next generation of neutron sources in the United States, embodied at two extremes in size by the SNS national laboratory and the regional university-based LENS facility. For many neutron scattering instruments, detector specifications call for high rate capability, large area coverage, high spatial resolution, and low gamma sensitivity. Currently, no detector satisfies this demanding set of requirements. To meet this set of requirements, this project will develop a detector consisting of a scintillator with two perpendicular arrays of wavelength-shifting optical fibers. In this configuration, neutrons are incident on the front face of the scintillator, and scintillation light is collected in two perpendicular arrays of wavelength-shifting (WLS) fibers optically coupled to the scintillator. The fibers conduct the scintillation light to multi-anode photomultiplier tubes (MAPMTs), which produces analog pulse information that is decoded by electronics to determine the coordinates of the neutron capture event. Phase I studied the light balance of the scintillator/fiber arrangement and implemented prototype data acquisition electronics and software appropriate for a crossed-fiber readout system. A prototype scintillator/WLS-fiber detector was built, which demonstrated the feasibility of these technologies. Phase II will design, optimize, and construct a full-scale prototype of a neutron imaging detector with improved position resolution, efficiency, and maximum counting rate capability. A state-of-art electronics readout system will be developed, and the detector will be thoroughly tested in a thermal neutron beam. Commercial Applications and Other Benefits as described by the awardee: Improved neutron detection devices should expand the scope of scientific research and development possible at neutron science instruments at both National and University facilities. Extensions of the technology may find use as large area neutron detectors for homelend security applications.