Comparison of CaF2 and LiF measurements of energy deposition rates in materials irradiated in a large 60Co facility

Energy deposition rates in various materials irradiated in a large 60Co facility have been measured using both CaF2 and LiF TLDs. Since the relationship between energy deposited in the TLD and that deposited in the surrounding medium (1/f factor) was different for the two types of TLD, the experiments provided a useful check on dosimetric measurements of γ-heating effects in irradiated target assemblies. One-dimensional photon transport calculations were carried out for estimating the γ-spectrum at each location, and hence appropriate 1/f factor for each TLD. In spite of the simplicity of such a model reasonable agreement was generally obtained for the CaF2, LiF measurements even in the case of a high-Z material such as lead. This was explained by the relatively rapid removal of Compton-scattered low-energy γ-rays by such a material, which reduced the sensitivity of the results to errors in the calculated γ-spectra.