Recent works proved the possibility of using common low-cost plastic polymers like polyethylene naphthalate (PEN) as a scintillator for radiation sensing applications. Scintillators are transparent materials that emit light upon excitation by energetic charged particles and are used to detect energetic particles and measure their properties. PEN offers excellent scintillation properties like high density (1.33g/cm3), a peak emission wavelength at ~ 425 nm and a light yield of roughly 104 photons/MeV. Because of these good properties and of its ease of manufacture and low cost, PEN is a very attractive solution for many applications, from dosimetry purposes in irradiation facilities or nuclear medicine to particles energy measurement in High Energy Physics (HEP) or Space experiments. Many of these applications require the instrumentation to operate in very high radiation environments and have pushed the problem of the detector's radiation hardness to the high priority level.
In this work, we investigate the radiation hardness of a PEN thin-film scintillator. Several samples have been irradiated in air with a 11 MeV proton beam and with a 1 MeV electron beam at the maximum doses of 15 Mrad and 80 Mrad, respectively. The radiation-induced damage has been measured in terms of light-yield loss as a function of the dose. Post-irradiation measurements have been performed by coupling the scintillator samples to a Photo-Multiplier Tube and by measuring the light induced by excitation with Am-241 and Cs-137 sources. This investigation revealed a reduction of the light yield emission, with similar trends for both irradiation beams. At the maximum dose of 80 Mrad, a light yield loss of ~35% has been observed. The results described in this work enrich the literature on radiation hardness studies on plastic scintillators, providing useful studies for the introduction of PEN scintillators in nuclear, space and HEP applications.
