Use of BC-523a liquid scintillator for simultaneous neutron spectroscopy and gamma counting with the implementation of a neutron history reconstruction algorithm
by Frey, Wesley D., Ph.D., OREGON STATE UNIVERSITY, 2009, 114 pages; 3352011

Abstract:

Real-time, high efficiency neutron spectroscopy has, historically, been a persistent challenge in the field of radiation detection and, for the most part, has gone unsolved. The most promising method to resolve this challenge, is the boron-capture technique using an organic scintillation system (BC-523a). Detectors that utilize this method possess an unusual property that allows them to be used for estimation of initial neutron energy over a large range of incident energies with very high intrinsic efficiencies. The two most significant problems with this method are that the recoil proton light response is non-linear (resulting in inaccurate neutron energy spectra) and the amount of analog circuitry required to process the pulses is prohibitive. This research resolves these two problems. The non-linear response is corrected by implementing a neutron history reconstruction algorithm. This algorithm tracks the theoretical amount of scintillation light generated by each neutron collision with hydrogen. Neutron interactions that do not produce a measurable scintillation pulse (non-hydrogen collisions and inelastic scatter photons leaving the detector’s active volume) will be characterized in MCNP, so that these signal losses can be accounted for. The majority of analog circuitry is replaced by a fast waveform digitizer and pulse processing program using digital filters. A plutonium beryllium neutron source was characterized. Results are available in real-time and are in good agreement with a historically accepted spectrum. Potential applications for this system include real-time mixed field dosimetry, neutron/gamma-ray sensitive portal monitors, and the possible replacement of the He-3 tube.

 
AdviserDavid M. Hamby
SchoolOREGON STATE UNIVERSITY
SourceDAI/B 70-04, p. , May 2009
Source TypeDissertation
SubjectsNuclear Physics; Radiation Chemistry; Nuclear physics
Publication Number3352011
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