Münster 2002 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 39: Nuclear Physics / Spectroscopy VI

HK 39.3: Talk

Thursday, March 14, 2002, 14:45–15:00, B

Dipole strength distribution in the well deformed nucleus ¹⁷⁸Hf and the systematics of the Scissors Mode in the even-even Hf nuclei — •M. Scheck¹, D. Belic¹, P. von Brentano², J.J. Carrol³, A. Gade², H. von Garrel¹, U. Kneissl¹, C. Kohstall¹, A. Linnemann², H.H. Pitz¹, F. Stedile¹, R. Toman³, and V. Werner² — ¹Institut für Strahlenphysik, Universität Stuttgart,D-70569 Stuttgart — ²Institut für Kernphysik, Universität zu Köln, D-50937 Cologne — ³Dep. of Physics and Astronomy, Youngstown State University, USA

The strength distribution of low-lying dipole excitations in ¹⁷⁶Hf was studied in nuclear resonance fluorescence experiments (NRF) performed at the Stuttgart bremsstrahlung facility (endpoint energy 4.1 MeV). Spectroscopic information on about 40 new spin 1 states in ¹⁷⁶Hf have been obtained. Ascribing to all observed K=1 states a positive parity, the detected total B(M1)↑ strength in the energy range of the Scissors Mode amounts to 3.1(4) µ_N² as for midshell rare earth nuclei [1] and is higher as in ^178,180Hf [2]. The M1 strength in ¹⁷⁶Hf fits well into the systematics, however, is more fragmented as in ^178,180Hf. On the other hand, the distribution patterns look quite similiar in all even-even Hf isotopes, with two strength concentrations at 2.7 and 3.7 MeV, respectively.
Supported by the DFG, contract Nos. Kn-154/31, Br-799/6,
[1] U. Kneissl et al., Prog. Part. Nucl. Phys. 37, (1996), 349.
[2] N. Pietralla et al., Nucl. Phys. A618, (1997), 147.