Köln 2004 – scientific programme
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HK: Physik der Hadronen und Kerne
HK 29: Nuclear Structure/Spectroscopy V
HK 29.4: Talk
Wednesday, March 10, 2004, 15:30–15:45, A
Lifetimes of Low-Spin States of 93Nb and 94Zr from Nuclear Resonance Fluorescence — •A. Chyzh1, C. Fransen1, U. Kneissl2, C. Kohstall2, A. Linnemann1, D. Mücher1, N. Pietralla1,3, H.H. Pitz2, M. Scheck2, C. Scholl1, F. Stedile2, P. von Brentano1, H. von Garrel2, S. Walter2 und V. Werner1 — 1Inst. für Kernphysik, Universität zu Köln — 2Inst. für Strahlenphysik, Universität Stuttgart — 3Dept. of Physics, State Univ. of New York at Stony Brook
Short-lived low-spin states of vibrational nuclei in the
A≈ 90 mass region have recently received a great deal of
attention due to evidences [1,2] for pronounced
structures with proton-neutron mixed-symmetry character.
Data on nuclei at the Z=40 proton sub-shell closure are
particularly important for understanding the evolution of
their collectivity because of the partial decoupling of
proton- and neutron-valence shells.
For tracing the evolution of mixed-symmetry states in this mass
region knowledge about 93Nb and 94Zr is desirable.
Gamma-ray spectroscopy of Nuclear Resonance Fluorescence (NRF)
has been a powerful part of the earlier discoveries.
We have performed NRF experiments at the Stuttgart
Dynamitron accelerator on 93Nb (photon endpoint
energy at 2.7 MeV) and 94Zr (endpoints at 2.7 and 4.1 MeV).
Several short-lived dipole and quadrupole excitations were observed.
Level lifetimes, branching ratios and γ-decay matrix
elements will be presented and discussed.
Supported by the DFG under Kn 154/31 and Pi 393/1-2,
and by the NSF under PHY-0245018.
[1] N. Pietralla et al., Phys. Rev. Lett. 81 1303
(1999).
[2] V. Werner et al., Phys. Lett. B550 140 (2002).