Gamma-Ray Induced Conductivity in Polyethylene and Teflon under Radiation at High Dose Rate

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Abstract
The conductivity induced by gamma radiation from Co60 has been measured for polyethylene and Teflon as functions of temperature, dose rate, and applied voltage. The range of dose rates was from about 103 to 105 R/h and of the temperature from 190° to 300°K. The value of Δ, which shows the dependence of the induced current i on the dose rate R, i.e., i ∝ RΔ, varies from 1 (characteristic of the monomolecular recombination) to ½ (characteristic of the bimolecular recombination) with decreasing temperature. In both polymers, below about 240°K the induced current at a thermal equilibrium was independent of temperature, although it was slightly increased with decreasing temperature. From the investigation of temperature and dose‐rate dependences, it is considered that the thermal electrons are dominant as charge carriers above 230°K, but fast electrons at below that temperature.