K[superscript pi] = 0[superscript +] 2.29 s isomer in neutron-rich [superscript 174]Tm

Abstract

Gamma-ray and conversion-electron spectroscopy have established the existence of a 2.29(1) s, K[superscript pi] = 0[superscript +], isomeric state in neutron-rich [superscript 174]Tm. The isomer deexcites via 100- and 152-keV electromagnetic transitions. First results from a newly commissioned Si(Li) detector array have established their M1 and E3 multipolarities, respectively. The single-particle configurations of the excited states suggest that the E3 transition originates from a [pi]h[superscript −1][subscript 11/2] [right-pointing arrow] [pi]d[subscript 3/2] configuration change, whereas the M1 transition occurs between members of a Gallaghar-Moszkowski doublet. From the measured half-life, the deduced B(E3) value of 0.024(2) W.u. is highly hindered. The reported measurements resolve ambiguities in the previously proposed [beta] decay scheme of [superscript 174]Er to [superscript 174]Tm.