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Collinear laser spectroscopy of fast atomic beams has been established as one of the main tools to perform precision experiments with atoms containing short-lived nuclei. Although highly sensitive, the spectral resolution of these techniques is typically limited to several MHz. Here, we study the use of transient interference phenomena to potentially improve the experimental resolution. Previous attempts to implement Ramsey-type measurements with fast beams were limited by the lack of understanding of the observed line shapes. By using a simple model, we provide a satisfactory description of the previously observed line shapes, and propose alternative experimental schemes to improve the resolution in fast ion-beam experiments., 7 pages without references, 8 figures

In spite of the high-density and strongly correlated nature of the atomic nucleus, experimental and theoretical evidence suggests that around particular 'magic' numbers of nucleons, nuclear properties are governed by a single unpaired nucleon1,2. A microscopic understanding of the extent of this behaviour and its evolution in neutron-rich nuclei remains an open question in nuclear physics 3-5. A textbook example is the electromagnetic moments of indium (Z = 49) 6, which are dominated by a hole with respect to the proton magic number Z = 50 nucleus. They exhibit a remarkably constant behaviour over a large range of odd-mass isotopes, previously interpreted as pure "single-particle behaviour". Here, we present precision laser spectroscopy measurements performed to investigate the validity of this simple single-particle picture. Observation of an abrupt change in the dipole moment at N = 82 reveals that while the single-particle picture indeed dominates at neutron magic number N = 82 2,7, it does not for previously studied isotopes. We present state-of-the-art nuclear theory developed to investigate the details of the nuclear forces that describe the experimental results. The emergence and disappearance of single-particle behaviour was reproduced from an ab initio theory, including challenging many-body correlations in these large, complex nuclei. The inclusion of time-symmetry-breaking mean fields is shown to be essential for a correct description of the nuclear electromagnetic properties within the Density Functional Theory framework. Until now, such time-odd channels have been poorly constrained, but are essential to provide accurate predictions of nuclear properties necessary for searches of new physics with neutrinos 8,9 and studies of fundamental symmetries 10,11. These findings are key to understand the microscopic origin of nuclear electromagnetism and the emergence of single-particle phenomena from complex nuclei.

Communications Physics 3(1), 107 (2020). doi:10.1038/s42005-020-0348-9, Published by Springer Nature, London

Beta-nuclear magnetic resonance (NMR) spectroscopy is highly sensitive compared to conventional NMR spectroscopy, and may be applied for several elements across the periodic table. Beta-NMR has previously been successfully applied in the fields of nuclear and solid-state physics. In this work, beta-NMR is applied, for the first time, to record an NMR spectrum for a species in solution. 31Mg b-NMR spectra are measured for as few as 10^7 magnesium ions in ionic liquid (EMIM-Ac) within minutes, as a prototypical test case. Resonances are observed at 3882.9 and 3887.2 kHz in an external field of 0.3 T. The key achievement of the current work is to demonstrate that beta-NMR is applicable for the analysis of species in solution, and thus represents a novel spectroscopic technique for use in general chemistry and potentially in biochemistry. ispartof: ChemPhysChem vol:15 issue:18 pages:3929-3932 ispartof: location:Germany status: published