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HK: Physik der Hadronen und Kerne
HK 31: Nuclear Physics / Spectroscopy V
HK 31.2: Talk
Wednesday, March 13, 2002, 14:30–14:45, C
New experimental campaign on the 20Ne(4+) g factor+ — •J. Leske1, K.-H. Speidel1, O. Kenn1, S. Schielke1, G. Müller1, J. Gerber2, N. Benczer-Koller3, and G. Kumbartzki3 — 1Institut für Strahlen- und Kernphysik, Univ. Bonn, D-53115 Bonn — 2Institut de Recherches Subatomiques, F-67037 Strasbourg, France — 3Dept. of Physics and Astronomy, Rutgers Univ., New Brunswick, NJ 08903, USA
In view of the eminent role of 20Ne for nuclear structure calculations the early measurements of magnetic moments on the first 2+ and 4+ states have caused tremendeous turmoil (see e.g. [1]). All these experiments in which the technique of transient magnetic fields was employed have yielded surprisingly a much smaller g factor for the 4+ state compared to the 2+ state. It was argued that in analogy to heavy nuclei the pronounced backbending in 20Ne might be responsible for this observation. However, such a scenario would be in striking contradiction with isospin conservation: for pure T=0 states the g factors of 2+ and 4+ should be equal to g ≃ +0.5. Sensible T=1 admixtures cannot explain the observed large difference. New measurements were performed at the Cologne tandem accelerator in substantially improved experimental conditions. The states of interest were populated in the reaction 12C(12C,α)20Ne using a technically improved multilayered target with evaporated Gd. Deexcitation γ rays were measured in coincidence with α particles emitted at backward and forward angles implying two different Ne velocities. Experimental details and preliminary results will be discussed.
+ supported by DFG
[1] K.-H. Speidel et al., Nucl. Phys. A378 (1982) 130