Large irradiation doses can improve the fast neutron/gamma discriminating capability of plastic scintillators

Abstract

When new materials appear as potential alternatives for radiation detection, several criteria have to be fulfilled. The one presented herein is the response variation to large irradiation doses of neutron/gamma discriminating plastic scintillators. Thus, several samples were exposed to high gamma doses reaching 10 kGy. They were characterized in terms of gamma spectrometry and fast neutron/gamma discrimination, prior to and after irradiation. Results show an unexpected increase of the figure of merit (FoM), which is the numerical value for n/γ discrimination performances. An in-depth investigation evaluates the physicochemical impact of such large doses within the material. The characterization includes photophysics, radiation/matter interaction and chemical analyses (EPR, H NMR, fluorescence spectroscopy and HRMS).

Progress in Fast and Red Plastic Scintillators

“…Their trick was to irradiate the scintillator with electrons created from a LINAC, thereby reducing the 35 ns preliminary decay time down to 5 ns only by molecular degradation. However, the scintillator revealed to recover from irradiation (as they use to be [10]) and the decay time reincreased accordingly. Since this seminal paper, several strategies have been tested towards the preparation of new red-emitting plastics (Table 1), with the use of organic fluorophores showing highrange aromaticity or internal Förster energy transfer, organometallics, BODIPY or xanthene derivatives, or more recently with organic molecules showing thermally activated delayed fluorescence (TADF).…”