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HK: Physik der Hadronen und Kerne

HK 29: Nuclear Structure/Spectroscopy V

HK 29.5: Vortrag

Mittwoch, 10. März 2004, 15:45–16:00, A

Lifetime Measurements for Dipole Bands in ¹⁴¹Eu and ¹⁴²Gd with EUROBALL — •R.M. Lieder¹, E.O. Podsvirova^1,2, A.A. Pasternak^1,2, W. Gast¹, H.M. Jäger¹, T. Venkova^1,3, S. Chmel⁴, A. Dewald⁵, D. Bazzacco⁶, E. Farnea⁶, R. Menegazzo⁶, S. Lunardi⁶, G. de Angelis⁷, D.R. Napoli⁷, A. Gadea⁷, G. Duchêne⁸, W. Urban⁹, T. Morek⁹, and T. Rzaca-Urban⁹ — ¹IKP, FZ Jülich, D-52425 Jülich — ²A.F. Ioffe PTI, RU-194021 St. Petersburg — ³INRNE, BAS, BG-1784 Sofia — ⁴HISKP, Univ. Bonn, D-53115 Bonn — ⁵IKP, Univ. Köln, D-50937 Köln — ⁶INFN, Sezione di Padova, I-35131 Padova — ⁷INFN, LNL, I-35020 Legnaro — ⁸IReS, F-67037 Strasbourg — ⁹IEP, Univ. Warsaw, PL-00-681 Warsaw

Lifetimes in ¹⁴¹Eu and ¹⁴²Gd have been measured in a DSAM experiment with EUROBALL IV at IReS Strasbourg using the ¹¹⁴Sn(³²S,ypxn) reaction at a beam energy of 160 MeV. As target a selfsupporting metallic ¹¹⁴Sn foil of 8 mg/cm² thickness has been used. The initial recoil velocity was v/c = 2.2%. Lifetimes have been deduced for dipole bands in ¹⁴¹Eu and ¹⁴²Gd. In total 26 values were obtained. Two of the dipole bands in ¹⁴²Gd are considered to have π h_11/2² ⊗ ν h_11/2⁻² and π h_11/2¹ ⊗ π g_7/2⁻¹ ν h_11/2⁻² configurations, respectively, and to experience band crossings. The dipole bands in ¹⁴¹Eu may result from the former by subtraction of an h_11/2 proton. The deduced B(M1) and B(E2) values are generally well reproduced in the framework of the tilted axis cranking model. The results indicate that these bands can be considered as magnetic rotational bands.

The work was partly supported by the German-Russian WTZ contract RUS 99/191 and by the EU contract HPRI-CT-1999-00078.