Radiation-Induced Currents in Coaxial Cables

The effects of gamma and neutron radiation on coaxial cables should be described as a current due to kinetically moved charge and a conductivity. Simple models, using known cross sections for gamma and neutron interactions can be used to calculate the amount of charge displacement. The radiation-induced conductance of a cable can also be estimated from data on the dielectric material. Experimental data frequently show larger initial response than the estimates. The observed current is proportional to instantaneous dose rate or flux, but the proportionality factor is a generally decreasing function of dose or fluence, even changing signs in some cases. The anomalies suggest relaxation of space charges created in the dielectric by the manufacturing process or by physical motion.