Köln 2004 – wissenschaftliches Programm
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HK: Physik der Hadronen und Kerne
HK 10: Poster Session: Nuclear Structure/Spectroscopy
HK 10.2: Poster
Dienstag, 9. März 2004, 13:30–15:30, Foyer
Shell model analysis of Q-phonon purity around A=90 ∗ — •V. Werner, P. von Brentano, and N. Pietralla — Institut für Kernphysik, Universität zu Köln
It will be shown that collective degrees of freedom still dominate low-lying levels in nuclei with only few valence particles around A=90. Nuclei with neutron number N=52 were investigated during the last years and states were identified as so-called symmetric and mixed-symmetric (MS) states. MS means that a part of the wave function is anti-symmetric under the exchange of protons and neutrons. Due to the sub-shell closure at Z=38 one may assume that the Q-phonon scheme, building the low-lying levels in nuclei by acting with the quadrupole operator on the ground state, breaks down in this region. Therefore, shell model calculations were performed for 92,94Zr and 94Mo. The Q-phonon scheme, distinguishing between F-scalar and F-vector Q-phonons holds to a large extent for 94Mo, comparable to findings in the Ba isotopic chain by the Tokyo MCSM group [1]. For the Zirconium isotopes with severely broken F-spin [2] the picture regarding seperately symmetric and MS Q-phonons indeed starts to break down. Nevertheless, it is shown that the Q-phonon scheme itself still holds to about 80 % in 92Zr showing that the main configurations of the lowest two 2+ states are still one-phonon configurations.
[1] N. Shimizu et al., Phys. Rev. Lett. 86 (2000) 1171.
[2] V. Werner et al., Phys. Lett. B 550 (2002) 140. ∗ supported by the DFG under contract Br799/11-1