Time response of poly (ethylene naphthalate) light emission to charged particles

Poly (ethylene naphthalate) (PEN) has attracted attention as an undoped scintillation material. It is essential to understand its fundamental properties for future applications. Here, we show unique time responses of PEN light emission generated by charged particles. Light emission decays from a 5 mm thick PEN sample exposed to Am-241 and Sr-90 radioactive sources were both represented by two exponential functions for prompt and delayed components. The prompt and delayed decay constants for the alpha particles were tau(P) = 28.7 +/- 0.6 ns, tau(D) = 161.4 +/- 6.7 ns, respectively. In comparison, the prompt and delayed decay constants for the beta particles were tau(P) = 28.9 +/- 0.2 ns, tau(D) = 257.0 +/- 26.3 ns, respectively. We thus revealed an attractive feature that the delayed decay constants were significantly different for the two charged particles. In addition, the delayed/prompt light intensity ratios were 0.51 +/- 0.04 for the alpha particles and 0.11 +/- 0.02 for the beta particles. These differences caused the light pulses to be dependent on the type of charged particles. This knowledge enhances the advantages of PEN for radiation detection.