Studies on Internal Bremsstrahlung Radiation Accompanying Second Forbidden β-Decay of 36 Cl and 99 Tc

The internal bremsstrahlung (IB) radiation accompanying the β-decay of the second forbidden β- transtionof 36 Cl and 99 Tc sources are Studied. The IB measured using a scintillation -spectrometer. It was analyzed by the variable width peeling-off-method, and then corrected applying the proper corrections. The analyzed and corrected IB spectrum was compared with those calculated according to Monte Carlo simulation and modified KUB calculations(M.KUB).It was found that the present experimental results have a better agreement with the theory than the previous work. Also It was found that the present experimental results are in a better agreement with M.KUB calculations than Monte Carlo simulation. This may be due to that the effect of Coulomb-charge(Z) on the IB process is treated in a more refined manner in M.KUB calculations than Monte Carlo Simulation.The 36 Cl and 99 Tcsources have the same degree of forbiddness but different values of Coulomb charge (Z)and different values of β-endpoint energy( 709 KeV and 292 KeV respectively). Therefore the effects of Coulomb charge (Z) and values of β-endpoint energy on the IB-processare studied. It was found that these effects have a large contribution into IB-spectrum for the sources of larger Coulomb charge (Z) and lower β-endpoint energy , as in the case of 99 Tc-source.