Development of a Calibration System for Dosimetry and Radioactivity of Beta-Emitting Sources

This study aims to develop a calibration system for radioactivity of beta sources using a calibration constant which derived from comparing measurement and simulation. It is hard to measure the activity of beta emitter isotope due to selfabsorption and scattering. So the activity involves high levels of uncertainty. The surface dose of Sr/Y-90 standard isotope was measured using extrapolation chamber and calculated using Monte Carlo. The activity (4.077 kBq) of source was measured by NIST measurement assurance program. And several correction factors were calculated Monte Carlo method. The measurement result was corrected by correction factors. The calibration constant was defined as the ratio of surface dose to activity. It was 4.5×10-8 and 6.52×10-8 for measurement and Monte Carlo, respectively. There was about 15.4% difference in the calibration constant determined by the two techniques. The depth uncertainty makes the difference because of high dose gradients. Some correction factors have error due to scattering by detector geometry. A test source will be produced by HANARO. The activity will be calculated using calibration constant. The activity will be performed cross-calibration with NIST. Finally, the system will provide accurate information of sources.