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HK: Physik der Hadronen und Kerne
HK 19: Nuclear Structure/Spectroscopy III
HK 19.3: Talk
Tuesday, March 9, 2004, 16:30–16:45, D
New Insights into the Nuclear Structure of 42,44,46Ca from g Factor and B(E2) measurements of 21+ States+ — •S. Schielke1, K.-H. Speidel1, O. Kenn1, J. Leske1, D. Hohn1, H. Hodde1, J. Gerber2, P. Maier-Komor3, O. Zell4, Y.Y. Sharon5, and L. Zamick5 — 1Helmholtz-Institut für Strahlen- und Kernphysik, Univ. Bonn — 2Institut de Recherches Subatomiques, Strasbourg, France — 3Physik-Dept. TU München — 4Institut für Kernphysik, Univ. Köln — 5Department of Physics and Astronomy, Rutgers Univ., USA
The low-level structure of calcium isotopes is generally characterized by the valence neutrons in the fp shell and a 40Ca core. The gradual filling of the f7/2 shell with neutrons for 42,44,46Ca, between doubly-magic 40Ca and 48Ca, causes strong variations in the excitation energies and B(E2)’s of their 21+ states. If fp shell neutrons are the dominant components in the nuclear wave functions one expects for these states negative g factor values (g≃ −0.4). From recent g factor measurements, employing projectile Coulomb excitation and the transient field technique, however, very surprising results were obtained. For 42,44Ca(21+) positive values of g factors were observed which could only be explained by shell model calculations including substantial cross-shell configurations from 40Ca core excitation [1]. In contrast, a recent first measurement on 46Ca(21+), using an enriched 46Ca beam, however, yielded a negative g factor, in complete disagreement with the positive value prediction. Evidently, in this case the valence neutrons of the fp shell play the dominant role.
+ supported by the DFG under Sp 190/9-2
[1] S. Schielke et al., Phys. Lett. B 571(2002)29