Absorption Induced in Optical Waveguides by Pulsed Electrons as a Function of Temperature, Low Dose Rate Gamma and Beta Rays, and 14 MeV Neutrons

Abstract

Three separate studies of radiation-induced absorption in glass and plastic waveguides have been completed. First, the absorption induced by low dose-rate 60Co gamma rays and 90Sr beta rays has been measured and compared with results obtained using higher dose rates. The comparison shows the absorption is independent of dose-rate from 500 rads/day to 106 rads/day to total doses of 6 x 104 rads. Second, the absorption induced in optical fibers by 14 MeV neutrons has been measured. The data were compared with results from 60Co gamma-ray irradiations using calculated values of the neutron ionizing dose as a basis of comparison. The results show that the absorption induced by 14 MeV neutrons at the fluences reported here is determined by the neutron ionizing dose in the spectral region from 400 nm to 1100 nm. Third, the effects of temperature on the transient absorption following pulsed electron irradiation has been measured. Predictions from kinetic models for geminate recombination, tunneling, thermal untrapping, and impurity-associated scavenging were compared with the experimental data. The results appear to identify kinetic processes that determine recombination in various irradiated waveguides.