The low temperature electric quadrupole orientation of184Ir and185Ir in rhenium

Abstract

The half-lives of184Ir,185Ir and186Ir have been determined to be 3.14(2) h, 14.4(1) h and 16.64(3) h, respectively. The quadrupole frequenciesv Q = e2qQs/h of184Ir and185Ir in rhenium single crystal have been determined to be Qs(184Ir) = + 2.0(3) b MHz and Qs(185Ir) = +2.0(3) b MHz. Adopting the value of −3.6(2)×1017 V·cm−2 for the electric field gradient eq at T=0 K, the values of the ground-state spectroscopic quadrupole moments of these isotopes are determined to be Qs(184Ir)=+2.0(3) b and Qs(185Ir)=−2.5(3) b. The185Ir moment is only consistent with the ground state Nilsson configuration $$I^\pi K = \tfrac{5}{2} - \tfrac{1}{2}$$ , the184Ir moment is consistent with K≥4 with a predominant K=4 component, in disagreement with K=0,1 found for186Ir. Our analysis differs in detail from the recent nuclear orientation study by Hagn et al.[1].