Gamma dosimetry by cobalt glass

A reliable method of cobalt glass dosimetry is presented for practical measurements in gamma-irradiation facilities. An empirical formula for the fading correction of radiation-induced coloration is given as a function of the optical density change, fading constant, exposure time and time elapsing between irradiation and read-out. The effect of temperature on the fading rate is negligible between 00C and 500C. An empirical equation for dose evaluation, with the correction formula, is developed. The doses can be obtained with good reproducibility (+-2% S.D.) in the range of 104 to 106 R; Accuracy of measurements is discussed. The dosimeters irradiated can be re-used by annealing at 5000C. Applications to exposure-rate mapping in radiation field and depth, dose measurement, comparison with other solid-state integrating dosimeters and practical procedure of dosimetry are also described. (auth.)