Laser-assisted spectroscopy of Au and Na isotopes at ISOLDE

Lasers are a powerful spectroscopic tool that have been exploited for decades to elucidate information about nuclear structure. Presented in this work are two different complementary laser interaction studies. The first is a combined laser spectroscopy and α-decay study of odd-odd isotopes 180,182Au, while the second highlights the recent developments at ISOLDE’s new laser polarisation beamline, culminating in the most precise deduction of the magnetic moments of 26−31Na to date. The investigation of laser-ionized odd-odd isotopes 180,182Au was performed using the Resonant Ionisation Laser Ion Source, Windmill and ISOLTRAP Multi-Reflection Time-of-Flight Mass Spectrometer. A complex fine structure α-decay pattern of 180Au was deduced providing an insight into the low-lying levels in the daughter nucleus 176Ir. The α-decay branching ratio of bα(180Au) = 0.58(10) % has also been derived, permitting calculation of the reduced α-decay widths and determining the degree of hindrance of respective α-decay branches. From complementary measurements of the hyperfine structure, magnetic moments of μI(180Au) = 0.83(7) μN and μI(182Au) = +1.68(5) μN were deduced. Based on the observed hyperfine structure pattern, a preferred ground state spin I(180Aug) = (1+) is proposed, and the assignment of I(182Aug) = 2+ in this work, is consistent with previous studies. The magnetic moment of 26Na, has been determined for the first time with parts-per-million precision, which is a hundred-fold improvement over the usual precision achievable for such short-lived nuclei. This achievement was possible by applying the ultrasensitive β-detected Nuclear Magnetic Resonance technique to a liquid-state sample at the laser polarization beamline. This result, combined with data from the literature, has further improved the uncertainty of the magnetic moments of 27−31Na to the dozen ppm level. Extending this approach to other isotopic chains would enlarge the palette of β-NMR nuclei to a variety of new isotopes across the nuclear chart.