hrvatski

Određivanje energijskih spektara Co-60 u vodi pomoću CaF_2:Mn i Frickeovog dozimetra

To calculate dose in water from the results of doses measured by different dosemeters, dosemter-to-water correction factors have to be used. A critical parameter in the calculation is the ratio of mass energy absorption coefficients, which in the case of dosimetry systems with a different energy dependence in comparison with water, strongly depend on the spectral characteristics of the photon radiation. For the evaluation of spectra in water, the pair of dosimeters with different energy dependences could be used. In this work, photon energy spectra at different depths in water irradiated with 60-Co source were evaluated using a pair of dosemeters: CaF2:Mn dosemeter with a large energy dependence in comparison with water and Fricke dosemeter which is practically water equivalent. The bases of the spectra evaluations are the photon fluence spectra as a function of depth in water calculated by Seltzer. The ratios of dose readings of CaF2 (relative to those obtained by an unscreened 60-Co source) and the results obtained by Fricke dosemter, giving Fricke-to-CaF2 correction factors, were compared with water-to-CaF2 correction factors calculated using the Burlin's cavity theory. The results enabled the evaluation of the quality of the 60-Co source used. For estimated spectra, the experimental values of water-to-CaF2 correction factors were in very good agreement with the values calculated using cavity theory.

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