Alanine-polystyrene dosimeters prepared by injection moulding

The alanine-polystyrene dosimeters analysed by electron spin resonance (ESR) spectrometry were manufactured for large-scale use as a routine dosimeter in industrial radiation processing facilities by using an injection moulding method. Injection moulding enables us to achieve mass production of uniform dosimeters at a reduced cost. Their primary characteristics for dosimetry were studied in terms of their gamma-ray dose-response at radiation processing dose levels, precision, and effect of temperature during irradiation at an absorbed dose of 1 kGy. The precision of dose-response in the range 0.1-100 kGy is within ± 2% at a 68% confidence level with and without correction for sample-to-sample mass scattering. The irradiation temperature coefficient for dosimeters irradiated to 1 kGy is estimated to be 0.25%/oC, by normalizing to those irradiated at 25oC in the temperature range from 5 to 45oC. The fading of the radiation-induced ESR signal at doses of 0.1-100 kGy at 25oC and r.h. 40% is <1% for at least 2 months after irradiation. (Author)