Abstract
Neutron scintillator films composed of a Eu2+-doped CaF2-AlF3-6LiF (Eu:CALF) polycrystalline ceramic powder and a poly(vinylidene fluoride) (PVDF) polymer matrix have been fabricated for neutron position-sensitive detectors (n-PSDs). Scintillation light yield and neutron detection efficiency have been measured as a function of film thickness (L) in the range of L=0.08-1.0 mm. The light yields of the films are 17,000-19,000 photons per thermal neutron. Based on a photon diffusion model in disordered media, the mean-free path of scintillation photons is 1.25±0.35 mm. Light emission cone size, the Full-width-at-half-maximum (FWHM) of spatial distribution of emitted light, is expected to increase with the film thickness. There is a large difference in the longest lifetime component (~800 ns) between neutron and gamma events at L≦0.39 mm, but this difference diminishes for films thicker than 0.39 mm, making neutron-gamma-discrimination (NGD) harder for these thicker films. The NGD ratio, or neutron-gamma-efficiency ratio, has been estimated using primitive digital-signal processing and machine-learning algorithms for a 1.0-mm-thick film. It reaches (2-3) x 105 using Principle Component Analysis (PCA) and 2-feature based pulse-shape discrimination methods, but they give a low thermal-neutron detection efficiency (~10%). A conventional Nonnegative Matrix Factorization (NMF) and a Graph-regularized NMF (GNMF) algorithms generate NGD ratios of 1 x 107 and 8 x108, and thermal-neutron detection efficiencies of 15 and 37%, respectively. Potential applications of our microcomposite scintillation films include neutron scattering for materials research, and neutron imaging and spectroscopy for nondestructive testing and security.
Original language | English |
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Title of host publication | 2020 IEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2020 |
Publisher | Institute of Electrical and Electronics Engineers Inc. |
ISBN (Electronic) | 9781728176932 |
DOIs | |
State | Published - 2020 |
Event | 2020 IEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2020 - Boston, United States Duration: Oct 31 2020 → Nov 7 2020 |
Publication series
Name | 2020 IEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2020 |
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Conference
Conference | 2020 IEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2020 |
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Country/Territory | United States |
City | Boston |
Period | 10/31/20 → 11/7/20 |
Funding
Manuscript received Nov. 16, 2020. This work was supported by Key-Area Research and Development Program of Guangdong Province, China (2020B0303090001), and by Laboratory Directed R&D (LDRD) fund of ORNL, and by the Scientific User Facilities Division, Office of Basic Energy Sciences, US Department of Energy.