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HK: Physik der Hadronen und Kerne

HK 3: Kernphysik/Spektroskopie

HK 3.5: Talk

Friday, March 4, 2005, 15:15–15:30, TU MA004

Structure of the 2₁⁺ state in radioactive ⁶⁸Ge from g factor and lifetime measurements⁺ — •J. Leske¹, K.-H. Speidel¹, S. Schielke¹, O. Kenn¹, J. Gerber², P. Maier-Komor³, S.J.Q. Robinson⁴, Y.Y. Sharon⁵, and L. Zamick⁵ — ¹Helmholtz-Institut für Strahlen- und Kernphysik, Univ. Bonn, Germany — ²Institut de Recherches Subatomiques, Strasbourg, France — ³Physik-Dept. TU München, Garching, Germany — ⁴Univ. of Southern Indiana, Evansville, Indiana, USA — ⁵Rutgers Univ., Piscataway, NJ, USA

The g factor of the 2₁⁺ state of radioactive ⁶⁸Ge (T_1/2 = 270 d) has been measured for the first time. The technique used is based on α transfer from a ¹²C target to 180 MeV ⁶⁴Zn projectiles that incorporates the favourable conditions of inverse kinematics as in projectile Coulomb excitation. It also includes the good features of the transient field technique applied to the nuclear spin precessions. In addition, we have remeasured the lifetimes of several excited states using the Doppler-Shift-Attenuation method. All measurements were carried out at the Munich tandem accelerator. The g factor value obtained, g(2₁⁺) = +0.55(14), is in good agreement with the collective value, g = Z/A = +0.47, and is also consistent with the precise data of the stable even-A Ge isotopes. The deduced B(E2) values and the g factor have been interpreted in the framework of the spherical shell model assuming a closed ⁵⁶Ni core and neutron and proton orbitals in the fp shell model space. Among the various effective interactions used the FPD6 interaction without A–scaling yielded surprisingly the best overall agreement with the experimental data.

[⁺] supported by the BMBF