Weak transitions in160Tb decay

Abstract

The decay scheme of the 72.3d160Tb and γ-transitions in160Dy has been studied by γ-ray spectroscopy with high-efficiency Ge(Li) and HPGe detectors. The intensity of the 1004.8 keV γ-ray is measured to be 0.04±0.01 relative to 30 for the 879.353 keV γ-ray. Gamma-rays of energies 707.6 and 239.70 keV with relative intensities 0.010±0.005 and 0.002±0.001 are observed and assigned to160Dy. The energies and relative intensities of all other γ-rays are remeasured to remove anomalies in the previous reports. A new β-group of intensity (0.032±0.012)% and logft 11.2±0.2 is proposed to feed the 1288.6 keV level in160Dy. The total conversion coefficient of the 197.008 keV transition in160Dy is measured to be 0.22±0.08. The total andK-shell conversion coefficients of the 86.796 keV transition in160Dy are remeasured and the results obtained are 4.71±0.20 and 1.54±0.12, respectively. The results of the branching ratios of β and γ transitions are discussed. The band-mixing parametersz2 for160Dy is determined and it is observed that the measured γ-ray branching ratios do not lead to a unique value ofz2 for160Dy.