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Abstract

A study of the ground states of the laser-ionized and mass-separated odd-odd isotopes ^180,182Au was performed using the Resonance Ionization Laser Ion Source, Windmill detection setup and ISOLTRAP Multi-Reflection Time-of-Flight Mass Spectrometer at ISOLDE, CERN. A complex fine-structure α-decay pattern of ¹⁸⁰Au was deduced, providing insight into the low-lying levels in the daughter nucleus ¹⁷⁶Ir. An α-decay branching ratio of bα(¹⁸⁰Au)=0.58(10)% and a half-life of T1/2=7.2(5) s have also been derived, allowing for the calculation of the reduced α-decay widths and determining the degree of hindrance of respective α-decay branches. From complementary first in-source laser spectroscopy measurements of the hyperfine structure in atomic transitions of ^180,182Au, the nuclear magnetic moments of μ(¹⁸⁰Au)=−0.83(9)μN and μ(¹⁸²Au)=1.66(9)μN were extracted with an inclusion of a correction for the hyperfine anomaly. Based on the observed hyperfine structure patterns, and on the comparison of the measured and calculated μ values, a preferred ground-state spin and parity Iπ(¹⁸⁰Au^gs)=(1+) is proposed, and the earlier assignment of Iπ(¹⁸²Au^gs)=(2+) is confirmed. For ¹⁸⁰Au, the most probable proton-neutron Nilsson configuration of π3/2−[532]⊗ν5/2−[512] suggests the same proton state as in the heavier deformed odd-odd nuclei ^182,184Au.