Laser-assisted decay spectroscopy for the ground states of $^{180,182}$Au

A study of the ground states of the laser-ionized and mass-separated odd-odd isotopes $^{180,182}$Au 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 $^{180}$Au was deduced, providing insight into the low-lying levels in the daughter nucleus $^{176}Ir$. An $α$-decay branching ratio of $b_α$($^{180}$Au)=0.58(10)% and a half-life of $T_{1/2}=7.2(5)$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 $^{180,182}$Au, the nuclear magnetic moments of $μ$($^{180}$Au)=−0.83(9)$μ_N$ and $μ$($^{182}$Au)=1.66(9)$μ_N$ 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 $I^π(^{180}\textrm{Au}^{gs}=(1^+)$ is proposed, and the earlier assignment of $I^π(^{180}\textrm{Au}^{gs}=(2^+)$ is confirmed. For $^{182}$Au, 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 $^{180,184}$Au.