Experimental verification of dosimetry predictions of bremsstrahlung attenuation as a function of material and electron energy

Dose attenuation with depth in an absorber of on-axis bremsstrahlung generated from an electron target is measured. It is shown to agree within ±9% with Monte Carlo predictions as a function of absorber material (Al, Fe, Pb) and incident electron-beam energy (5.5-25.1 MeV). For this on-axis bremsstrahlung, 1 to 5 g/cm² of upstream and 0.2 to 1 g/cm² of downstream Al buffer are sufficient to provide electron equilibration for CaF₂ :Mn thermoluminescent dosimeters (TLDs) over the measured energy range of 5.5 to 25.1 MeV. Once effective equilibration has been established, an expression is given that can be used to predict the dose-area product per absorbed beam charge at a given incident beam energy in TLDs as a function of depth in absorbers, within a fixed solid angle centered about the beam axis. This expression is quantified for the measurements presented here