Berlin 2005 – wissenschaftliches Programm

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HK: Physik der Hadronen und Kerne

HK 3: Kernphysik/Spektroskopie

HK 3.7: Vortrag

Freitag, 4. März 2005, 15:45–16:00, TU MA004

Dominant neutron component in the ⁶⁸Zn(4₁⁺) wave function from g factor measurements⁺ — •J. Leske¹, K.-H. Speidel¹, S. Schielke¹, J. Gerber², and P. Maier-Komor³ — ¹Helmholtz-Institut für Strahlen- und Kernphysik, Univ. Bonn, Germany — ²Institut de Recherches Subatomiques, Strasbourg, France — ³Physik-Dept. TU München, Garching, Germany

The g factor of the 4₁⁺ state in ⁶⁸Zn has been measured for the first time employing projectile Coulomb excitation in inverse kinematics. A multilayered target consisting of thin layers of C/Gd/Ta/Cu was bombarded with a ⁶⁸Zn beam of 180 MeV provided by the Munich tandem accelerator. The γ rays emitted from the excited states were measured in coincidence with forward scattered carbon ions. Spin precessions occured in the transient field of the magnetized Gd layer. A Si detector was used for detection of the carbon ions whereas the γ rays were detected by pairs of NaI(Tl) scintillators and Ge detectors. The superior energy resolution of the Ge detectors was essential for separating the (4₁⁺ → 2₁⁺) γ line from neighbouring and Doppler-shifted (2₃⁺ → 2₁⁺) 1261 keV line in the forward hemisphere. The negative g factor deduced is a surprise as its sign contradicts large-scale shell model predictions. It can only be understood if g_9/2 neutrons are a strong component in the nuclear wave function. This result will be discussed in the context of similar measurements in ⁶⁴Zn for which the g factor of the 4₁⁺ state was found to be positive in agreement with the collective as well as shell model predictions.

[⁺] supported by the DFG