Description
Trends in nuclear excited-state observables along isotopic or isotonic chains can reveal changing nuclear shell structure and emerging physics away from stability. Nuclear magnetic moments, or g factors, are an important observable for challenging nuclear shell-model predictions due to their sensitivity to the ratio between broken proton and neutron pairs and their orbital occupation. However, to make meaningful comparisons one must have precise and accurate data. Measurements of g factors on states with sub-nanosecond lifetimes are challenging due to the kilotesla-magnitude magnetic fields required to induce a measurable interaction. Historically, an ion-solid interaction known as the transient field (TF) has been utilised. However, a first-principles description of how this field arises is elusive. Therefore, empirical parametrisations have been used to calibrate its strength. These parametrisations may inflate uncertainty up to 15% for otherwise precise measurements (<5%). Alternatively, relative measurements can be made to states with known g factors, i.e. to longer-lived states in neighbouring isotopes obtained using an alternative technique. However, these may be imprecise, and/or introduce complications such as static-field contributions. An alternative, the recoil-in-vacuum (RIV) technique, utilises the hyperfine fields present in ions recoiling into vacuum. These fields can be calculated precisely from first principles using atomic-structure theory. When used in a time-differential manner this technique shows promise to yield precise, calibration-independent results. This is achieved by modelling the net hyperfine interaction arising from the atomic states present across a single or multiple ionic species in the measurement. These results can be used to reduce the uncertainty in existing TF measurements by improving the precision of data points in the empirical calibration or scaling relative measurements directly. With the improved precision, shell-model calculations can be more critically evaluated.
| I am the presenting author | Yes |
|---|