［RIBF-ULIC-miniWS-012］Perspectives of shape transitions and β-decay half-lives in the neutron-rich A≈110 region near the r-process path

Neutron-rich nuclei with the mass number around A=110 have attracted considerable interest in the context both of nuclear structure and r-process nucleosynthesis. Theoretical r-process simulations based on a given type of mass model tend to underestimate the observed Solar-system isotopic abundance distributions. For Zr-Nb-Mo isotopes in the region of interest, the shape transitions from prolate, via gamma-soft, to oblate deformations are predicted to occur with increasing number of neutrons. The beta-decay half-lives of the Zr and Nb isotopes measured in the decay spectroscopy experiment at RIBF in 2009 are shorter than the predictions of standard models by a factor of two or more, suggesting that nucleosynthesis in the r-process can proceed more rapidly through this region than the expectations. New results obtained in this experiment also include the observation of interesting phenomena in nuclear-shape transitions such as the structural evolution in Zr isotopes, a possible oblate-shape isomer in 109Nb, and a large-amplitude gamma-soft (prolate-oblate) dynamics in 110Mo. The purpose of this workshop is to discuss these experimental results with theoreticians in the relevant fields, involving Professor Peter Möller from Los Alamos National Laboratory, focusing particularly on the interplay between the nuclear shape and mass. It is hoped that the workshop will deepen our knowledge concerning the underlying structural effects on the observed enhancement of the beta-decay rates and their impact on the r-process nucleosynthesis.