［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

Tuesday 27 Dec 2011, 13:30 → 18:00 Asia/Tokyo

Meeting Room 203 (RIBF Building)

Hiroshi Watanabe (RIKEN)

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.

Application to ULIC app_miniWS_A=110_Watanabe.pdf

Report report-form_A=110.pdf

13:30 → 13:35 Opening

Speaker: Dr Hiroshi Watanabe (RIKEN Nishina Center)

13:35 → 14:05 Beta-decay half-life measurement and future perspective

Speaker: Dr Shunji Nishimura (RIKEN Nishina Center)

14:05 → 14:40 Effects of shape transitions and fission-fragment accumulations to the r-procesee in the neutron-rich A=110 region

Speaker: Dr Hiroyuki Koura (JAEA)

14:40 → 15:10 Prolate-oblate shape coexistence and enhanced gamma-softness in neutron-rich Nb and Mo isotopes around A=110

Speaker: Dr Hiroshi Watanabe (RIKEN Nishina Center)

15:10 → 15:25 break

15:25 → 15:55 TBA

Speaker: Dr Toshiyuki Sumikama

15:55 → 16:30 Theoretical research on the isoscalar giant monopole resonance in Cd, Sn and Pb isotopes

Speaker: Prof. Li Gang Cao (Chinese Academy of Science)

16:30 → 17:00 Effect of tensor interaction on deformation and shell structure of SHE

Speaker: Prof. Hiroyuki Sagawa (Aizu University)

17:00 → 18:00 Discussions