Berlin 2005 – wissenschaftliches Programm
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HK: Physik der Hadronen und Kerne
HK 22: Postersitzung
HK 22.26: Poster
Montag, 7. März 2005, 16:30–18:00, TU MA141
Laser spectroscopy and β-NMR measurements on 11Li and on Mg isotopes around N=20 — •M. Kowalska1, K. Blaum1,2, D. Borremans3, P. Himpe3, P. Lievens3, S. Mallion3, R. Neugart1, G. Neyens3, N. Vermeulen3, and D. Yordanov3 — 1Universität Mainz, Germany — 2CERN, Switzerland — 3K.U.Leuven, Belgium
Measurements of nuclear moments are crucial for a better understanding of nuclear structure, in particular in connection with halo and shell effects. This is demonstrated for recent results on 11Li and 31Mg. Beams from ISOLDE are optically polarised with laser light and implanted into a host crystal. Scans of the optical excitation frequency show the hyperfine structure in the β-decay asymmetry. NMR measurements are performed for the laser frequency at resonance. Radio-frequency is applied and the nuclear g-factor and quadrupole moment are measured.
High-resolution NMR measurements were performed recently on the halo nucleus 11Li. They reveal a quadrupole moment significantly larger than that of the 9Li core, showing the influence of the halo neutrons on the proton core. Similar experiments took place on neutron-rich Mg isotopes, to further explore the "island of inversion". A combined measurement of the hyperfine structure and g-factor of 31Mg reveals an unexpected 1/2+ ground state, dominated by 2p-2h intruder configurations, proving a weakening of the N=20 shell closure. These investigations are being extended to 29Mg and 33Mg.
(Supported by BMBF and FWO Vlaanderen)