Precise Densitometer For Thin-Film Dosimeters

A precise densitometer for thin-film dosimeters has been developed in order to measure the radiation loading on accelerator equipment in the dose range from 10(3) to 5 X 10(5) Gy. With the help of this densitometer, the optical density S = Ig(I-0/I) of coloured thin-film based on polykaproamide (CO PD (F)-5/150) was measured in the region of S from about 10(-3) to 1.6. The accuracy was about 0.2% for S = 1.6. A CsI(TI) scintillator was excited by alpha-particles from a Pu-238 radioactive source and used as a standardized pulsed light-source. The apparatus and software used and the data processing equipment were industry supplied and quite identical to what is used for gamma spectrometry.