A fluorocarbon plastic scintillator for neutron detection: Proof of concept
Abstract
The fast neutron nuclear reactions, such as 19F(n, α)16N and 19F(n, p)19O, can be used to detect highly energetic neutrons due to their energy thresholds above which these activation reactions can occur. This was recently shown (Gozani et al., 2011 [2]) as a means to detect concealed nuclear materials via the detection of the high energy (≈3 MeV) prompt neutrons emitted during the photofission process.
Fluorine-loaded scintillation detectors, such as inorganic BaF2 and CaF2, and non-hydrogenous fluorocarbon (FC) liquid scintillators, such as Saint-Gobain BC-509 and Eljen Technology EJ-313, are possible candidates. The latter was selected and implemented in the above mentioned reference.
In our paper, we propose a new pentafluorostyrene-based plastic scintillator (F-plastic) which can be a good alternative to the abovementioned scintillators. The fluorine content of F-plastic is equal to 3.73×1022 atoms/cm3, and the F/H ratio is 1.66. The fluorescence and radioluminescence spectra of the F-plastic display an emission maximum centered approximately at 420 nm. The light output measured for gamma rays is 3100±300 photons/MeV, which is approximately 30% of the light output of the standard EJ-200 plastic scintillator and is similar to EJ-313. The response of the F-plastic to neutrons and gamma rays is presented and compared to the EJ-200 scintillator. Additionally, the n/γ pulse shape discrimination (PSD) was measured and showed improvement of the discrimination at neutron energies as high as 3 MeV.