Gamma Dose Rate Measurement Using RadFET

Abstract

Radiation-sensitive field-effect transistors (RadFET) are generally known for the measurement of total ionizing dose (TID) from gamma radiations. The use of an RadFET as a TID sensor is indispensable because of its characteristic dose rate-independent response. The only drawback with the RadFET, which we consider to be important, was its inability to measure the dose rate. We report here a novel methodology to extract an instantaneous dose rate information from the indigenous RadFET, which has been designed to measure an integral dose in the range from 10 mGy to 10 Gy. The methodology has enabled us to achieve a dose rate measurement sensitivity of 1838±9 counts per second (CPS) at 1±0.05 Gy/h for 60Co irradiation. The minimum dose rate that could be determined using the indigenous RadFET is 0.5 mGy/h, which is approximately three orders of magnitude better than reported to date using an RadFET dosimeter.