Speaker
Description
Lifetime measurements with the recoil distance Doppler-shift technique
have been performed to determine yrast E2 transition strengths in 178Pt.
The experimental data are related to those on neighboring Pt isotopes,
especially recent data on 180Pt, and compared to calculations within the
interacting boson model and a Hartree-Fock Bogoliubov approach. These
models predict prolate deformed ground states in Pt isotopes close to
neutron midshell consistent with the experimental findings.
Further, evidence was found that the prolate intruder structure observed in
neutron deficient Hg isotopes that is minimum in energy in 182Hg becomes
the ground state configuration in 178Pt and neighboring 180Pt with nearly
identical transition quadrupole moments. The new data on 178Pt are further
discussed in the context of the systematics along the Pt isotopic chain
with respect to an asymmetry of the level schemes relative to the neutron
midshell that is not expected in collective models. In addition, hints for
a sharp shape transition towards a weakly deformed or a quasi-vibrational
structure in 174,176Pt will be discussed based on existing data where
contradicting model approaches exist.
Supported by the Deutsche Forschungsgemeinschaft (DFG) under Contracts
No. FR 3276/1-1 and DE 1516/3-1.
