ESTIMATION OF PHOTON ENERGY-SPECTRA OF CO-60 IN WATER USING CAF2-MN AND FRICKE DOSIMETERS

Photon energy spectra at different depths in water irradiated with a C o-60 source were evaluated using a pair of dosemeters: a CaF2:Mn dosem eter with a large energy dependence in comparison with water and a Fri cke dosemeter which is practically water-equivalent The basis of the s pectra evaluations are the photon fluence spectra as a function of dep th in water calculated by Seltzer. The ratios of dose readings of CaF2 (relative to those obtained by an unscreened Co-60 source) and the re sults obtained by a Fricke dosemeter, giving Fricke-to-CaF2 correction factors, were compared with water-to-CaF2 correction factors calculat ed using Burlin's cavity theory. The results enabled the evaluation of the quality of the Co-60 source used. For estimated spectra, the expe rimental Values of water-to-CaF2 correction factors were in very good agreement with the values calculated using cavity theory.