Non-Langevin recombination and dose effects in the radiation-induced conductivity of polymers

The features of radiation-induced conductivity under both continuous irradi ation and strong pulse action is analyzed theoretically for polymers (PTFE and LDPE) exhibiting a non-langevin mechanism of the bulk recombination. Re combination in the "encounter pairs" occurring only during the exposure is demonstrated to be the dominant recombination process in this case. After t he maximum conductivity for continuous exposure has been reached, the trans ition to the decay law t(-1) is observed immediately in the course of expos ure, what is connected to the formation of radiation-induced traps (mainly the radical products of radiolysis). The effect of preliminary irradiation consists in a decrease in the nonstationary radiation-induced conductivity measured in the small-signal mode only during the exposure. The decay bf th e delayed component upon termination of the radiation pulse is almost unaff ected; only at the observation times greater than or equal to 0.1 s the dec ay can be accelerated due to the appearance of radiation traps generated by preliminary irradiation.