Total bremsstrahlung spectral photon distributions in metallic targets in the photon energy range of 5-10 keV by Tl beta particles

Total bremsstrahlung spectral photon distributions produced by beta particles of the ²⁰⁴Tl beta emitter in thick targets of Al, Ti, Sn and Pb targets were evaluated at photon energies from 5 keV to 10 keV. Experimental measurements were compared with the theoretical total bremsstrahlung spectral photon distributions obtained from Elwert corrected (non-relativistic) Bethe-Heitler theory and modified Elwert factor (relativistic) Bethe-Heitler theories for ordinary bremsstrahlung, and the modified Elwert factor (relativistic) Bethe-Heitler theory which includes polarization bremsstrahlung in the stripped atom approximation. The experimental results show better agreement with the modified Elwert factor (relativistic) Bethe-Heitler theory which includes the contribution of polarization bremsstrahlung. The contributions of polarization bremsstrahlung decrease with increased photon energy, particularly for medium and high Z elements. Hence its contribution cannot be neglected while studying the total bremsstrahlung spectral photon distributions in thick targets, produced by continuous beta particles in the studied energy region.