Experimental Check of Bremsstrahlung Dosimetry Predictions for 0.75 MeV Electrons

Bremsstrahlung dose in CaF2 TLDs from the radiation produced by 0.75 MeV electrons incident on Ta/C targets is measured and compared with that calculated via the CYLTRAN Monte Carlo code. The comparison was made to validate the code, which is used to predict and analyze radiation environments of flash x-ray simulators measured by TLDs. Over a wide range of Ta target thicknesses and radiation angles the code is found to agree with the 5% measurements. For Ta thicknesses near those that optimize the radiation output, however, the code overestimates the radiation dose at small angles. Maximum overprediction is about 14 ± 5%. The general agreement, nonetheless, gives confidence in using the code at this energy and in the TLD calibration procedure. For the bulk of the measurements, a standard TLD employing a 2.2 mm thick Al equilibrator was used. In this paper we also show that this thickness can significantly attenuate the free-field dose and introduces significant photon buildup in the equilibrator.