Decay of ⁸¹Sr

抄録

The β⁺ decay of ⁸¹Sr to the levels of ⁸¹Rb has been investigated with high resolution Ge(Li) detectors. The half-lives of ⁸¹Sr and ^81mRb were determined to be 22.15±0.22 and 30.59±0.28 min, resrectively. Energies and relative intensities of 80 gamma rays associated with ⁸¹Sr decay were measured precisely and 30 of them are new gamma rays. The level scheme of ⁸¹Rb was constructed by applying the Ritz rule and the intensity balance. Seventy three gamma rays were incorporated into the level scheme including eleven new levels at 245.29, 463.02, 486.69, 630.58, 711.93, 923.04, 1243.64, 1513.13, 1804.41, 1848.47 and 2165.53 keV. The possible spin-parities of ⁸¹Rb levels are proposed considering logft values and gamma-ray branching ratios. The level at 245.29 keV is assigned as the anomalous 5/2⁺ state.