Total bremsstrahlung photon yield and Z-dependence in thick targets produced by beta emitter 45Ca and 147Pm

The total bremsstrahlung photon yield in thick metallic targets (Al, Cu, Sn and Pb) produced by beta emitter 45Ca and 147Pm has been measured by using X-PIPS Si (Li) detector in the photon energy region 5-30 keV. The Z-dependence index ‘n’ and yield constant are determined in the photon energy region 5-30 keV. The Z-dependence index ‘n’ values obtained from experimental bremsstrahlung photon distributions shows better agreement with the index ‘n’ values obtained from the modified Elwert factor (relativistic) Bethe-Heitler theory, which includes the polarization bremsstrahlung into ordinary bremsstrahlung. It was observed, that a yield constant shows exponential decaying dependence on photon energy. Further, it has been found that the Z-dependence index ‘n’ values are not constant and decreases with increasing photon energy. The higher ‘n’ values than unity clearly indicates the inadequacy of theoretical models to represent the dependence of spectral shape of total bremsstrahlung on atomic number. It was observed that total bremsstrahlung photon yield increases with the increase in atomic number and with the decrease in photon energy.