Revisiting the decay scheme and half-life of 139Ba

Abstract

The decay of 139Ba to levels of 139La has been studied employing singles and \( \gamma\) -\( \gamma\) coincidence spectroscopy techniques, using four Compton suppressed Clover detectors. The \( \gamma\) -\( \gamma\) coincidence data obtained in the present work has been more conclusive as compared to the coincidence data obtained using NaI(Tl)-Ge(Li) detectors in the earlier investigations. The relative intensities of twenty-seven \( \gamma\) -ray transitions have been determined. The \( \gamma\) -ray transitions with energies 1044 and 1525keV, attributed to the decay of 139Ba in the previous works, have been found to be due to long-lived impurities. The 1691keV transition, previously assigned to the decay of 139Ba , is found to be mainly associated with an impurity with only a small fraction belonging to 139Ba decay. The half-life of 139Ba has been measured. The present work attempts to resolve some of the discrepancies in the previous investigations, which will be helpful in the precise determination of \( \beta\) -decay scheme of 139Ba.