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

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 𝑏_𝛼 ⁡(¹⁸⁰Au) = 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 ^180,182Au, the nuclear magnetic moments of 𝜇⁡(¹⁸⁰Au)=−0.83⁢(9)⁢𝜇_𝑁 and 𝜇⁡(¹⁸²Au)=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⁡(¹⁸⁰Au^gs)=(1⁺) is proposed, and the earlier assignment of 𝐼^𝜋⁡(¹⁸²Au^gs)=(2+) is confirmed. For ¹⁸⁰Au, the most probable proton-neutron Nilsson configuration of 𝜋⁢3/2^−⁢[532]⊗𝜈⁢5/2⁻⁢[512] suggests the same proton state as in the heavier deformed odd-odd nuclei
^182,184Au.