München 2006 – wissenschaftliches Programm
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HK: Physik der Hadronen und Kerne
HK 10: Kernphysik/Spektroskopie
HK 10.1: Gruppenbericht
Montag, 20. März 2006, 16:30–17:00, C
Nuclear moments and charge radii of n-rich Mg isotopes — •M. Kowalska1, K. Blaum1, K. Flanagan2, P. Himpe2, P. Lievens2, S. Mallion2, R. Neugart1, G. Neyens2, N. Vermeulen2, and D. Yordanov2 — 1Universität Mainz, Germany — 2K.U. Leuven, Belgium
Among other observables, ground state properties of nuclei, such as moments and charge radii, contribute widely to our understanding of nuclear structure, particularly in the context of shell closures. Of special interest is the ’island of inversion’ around Z=10-12, where data shows that N=20 is not a magic number. Mg isotopes in this region were studied via laser and β-NMR spectroscopy at ISOLDE, CERN. For laser spectroscopy (24−27Mg), the ion velocity is Doppler-tuned into resonance with laser light and resonances are observed in fluorescence. To obtain magnetic and quadrupole moments, we measure the hyperfine structure (HFS), and for charge radii, we determine the isotope shift for an atomic transition. β-NMR (29,31,33Mg) requires optical polarization and implantation into a crystal. The HFS is seen in β-decay asymmetry, using Doppler tuning, and NMR measurements are performed for the laser at resonance, with changing radio-frequency. Disappearance of asymmetry yields the Larmor frequency, and thus the g-factor. Recently we measured changes in mean square charge radii for 24−27Mg, which we plan extending to more n-rich isotopes, thus reaching the ’island of inversion’. We measured HFS for 27,29,31Mg, and β-NMR resonances of 29,31Mg yielding their g-factors and the unknown spin of 31Mg. Recently we also obtained β-asymmetry signals of 33Mg. We will present experimental techniques, results and their discussion.