Speaker
Dr
D. T. Yordanov
(CERN European Organization for Nuclear Research, Physics Department, CH-1211 Geneva 23, Switzerland)
Description
The island of inversion is commonly regarded as an island of deformation. Yet, the transition to a deformed configuration in the isotopes of magnesium is not well understood. This problem cannot be addressed by quadrupole-moment measurements due to nuclear spin 0 or 1/2 of most key isotopes. Experimental evidence from reaction studies as well as the spins and magnetic moments of 31,33Mg are consistent with considerable prolate deformation. However, in order to obtain a continuous picture of the evolution of the nuclear shape along the magnesium chain one has to measure a quantity accessible for all isotopes (odd and even) with the same experimental technique. Accordingly, a measurement of the rms charge radii of the neutron-rich magnesium isotopes will be presented for the first time.
This work was undertaken with the collinear laser spectroscopy setup at ISOLDE-CERN. The isotope shifts of 24-32Mg were measured using different detection methods for increased sensitivity to the exotic nuclei in the island of inversion. Classical fluorescence detection was used for the intense beams of 24-29Mg. Beta detection was applied on the odd isotopes 29Mg and 31Mg and used for isotope-shift measurements for the first time. The application of this technique was justified after a recent development of computer simulations of the beta-asymmetry produced by optical pumping. This approach is essential for extracting the small nuclear-volume effect contributing to the isotope shifts of light atomic systems. The equivalence of optical and beta detection is investigated on the basis of 29Mg, which is accessible with both methods, and thus used as a proof of principle. Fluorescence spectra of 30Mg were recorded by gating on the short release from the ISOLDE target. The case of 32Mg was investigated with the use of photon-ion coincidence.
The measurements on the rms charge radii of the neutron-rich magnesium isotopes will be presented with emphasis on the novel methodology for extracting accurate isotope shifts from beta-detection spectra. The results will be discussed in terms of deformation in light nuclei near N=20 and in the context of evolution of the shell structure away from stability.
| Is this an invited talk? (please answer yes or no) | No |
|---|---|
| Would you prefer your contribution to be an oral presentation? (please answer yes or no) | Yes |
| Would you prefer your contribution to be a poster presentation? (please answer yes or no) | No |
Author
Dr
D. T. Yordanov
(CERN European Organization for Nuclear Research, Physics Department, CH-1211 Geneva 23, Switzerland)
Co-authors
Mr
A. Krieger
(Institut für Kernchemie, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany)
Dr
C. Geppert
(Institut für Kernchemie, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany; GSI Helmholtz Centre for Heavy Ion Research GmbH, D-64291 Darmstadt, Germany)
Prof.
G. Neyens
(Instituut voor Kern- en Stralingsfysica, Katholieke Universiteit Leuven, B-3001 Leuven, Belgium)
Mr
J. Krämer
(Institut für Kernchemie, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany)
Prof.
K. Blaum
(Max-Planck-Institut für Kernphysik, D-69117 Heidelberg, Germany)
Mr
K. Kreim
(Max-Planck-Institut für Kernphysik, D-69117 Heidelberg, Germany)
Dr
M. Bissell
(Instituut voor Kern- en Stralingsfysica, Katholieke Universiteit Leuven, B-3001 Leuven, Belgium)
Mr
M. Hammen
(Institut für Kernchemie, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany)
Dr
M. Kowalska
(CERN European Organization for Nuclear Research, Physics Department, CH-1211 Geneva 23, Switzerland; present address: Max-Planck-Institut für Kernphysik, D-69117 Heidelberg, Germany)
Prof.
P. Lievens
(Laboratorium voor Vaste-Stoffysica en Magnetisme, Katholieke Universiteit Leuven, B-3001 Leuven, Belgium)
Mr
P. Vingerhoets
(Instituut voor Kern- en Stralingsfysica, Katholieke Universiteit Leuven, B-3001 Leuven, Belgium)
Prof.
R. Neugart
(Institut für Kernchemie, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany)
Prof.
W. Nörtershäuser
(Institut für Kernchemie, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany; GSI Helmholtz Centre for Heavy Ion Research GmbH, D-64291 Darmstadt, Germany)
