Measurement of ground-state β−-branching intensities of deformed rare-earth nuclides using a total absorption γ-ray spectrometer

The utility of the method using a total absorption γ-ray spectrometer system, operating in the 4 πγ-β coincidence mode, to measure ground-state β−-branching intensities of deformed rare-earth fission-product nuclei is discussed. For such nuclei it is demonstrated that, given sufficient information concerning the lower excitation states being populated and their de-excitation modes, precise values can still be obtained for their “ground-state” β−-branching intensities; where here the “ground-state” is defined to include both the true ground state and all excited states below a selected γ-ray discriminator level. Results obtained for 153Nd, 153Pm, 154Nd, 154Pm(1.7 min), 155Pm, 156Pm, 157Pm, 157Sm and 158Sm are presented and compared with existing published data.