Radiation-induced conductivity in polystyrene at extremely low (79 K) temperature

Abstract

Radiation-induced conductivity (RIC) of polystyrene has been studied experimentally and numerically in a broad time range from milliseconds to seconds at 79 K, which seems to have been done for the first time. It has been established that the hole dispersive transport is still operative but unlike the room temperature behavior it features an extremely small frequency factor (4 × 103 s−1) and accordingly low dispersion parameter (0.09). It has been shown that prompt conductivity per unit dose rate does not depend on temperature (290 or 79 K) and is equal to Kp=3.5×10−15Ω−1m−1Gy−1s (±20%) at 4 × 107 V/m. At 79 K, current–voltage characteristics of both prompt and delayed components are close enough and non-linear. Due to the contribution of the thermalized charge carriers, the RIC even at 79 K can be satisfactorily described by the semi-empirical Rose–Fowler–Vaisberg model based on the quasi-band multiple trapping mechanism just as it happens at room temperature.