Study of neutron-rich nuclei relevant to 1st and 2nd peak of r-process nucleosynthesis

2016 Fiscal Year Final Research Report

• Project/Area Number: 25247045
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Particle/Nuclear/Cosmic ray/Astro physics
• Research Institution: Institute of Physical and Chemical Research
• Principal Investigator: Nishimura Shunji 国立研究開発法人理化学研究所, 仁科加速器研究センター, 先任研究員 (90272137)
• Project Period (FY): 2013-04-01 – 2017-03-31
• Keywords: β崩壊 / ｒ過程 / 中性子過剰核 / 超新星爆発 / 中性子星合体 / 半減期

Outline of Final Research Achievements

High efficiency γ-ray detectors (Cluster Germanium detector) and β-ray detectors were introduced to investigate the role of the neutron-rich nuclei in the rapid-neutron capture process (r process) nucleosynthesis. In total, 234 β-decay half-lives were measured successfully during this research program. We found that newly measured 122 β-decay half-lives play important role in the determination of the shape of 1st and 2nd peaks of r-process elements. In addition, our results reduce the uncertainty of synthesis in the formation of heavier rare-earth elements. The neutron magic number N = 50 and 82 were investigated by studying the systematics of β-decay half-lives and excited states of 78Ni and 128Pd, respectively. The results suggest that neutron shell closure at N = 50 and 82 are still robust for such very neutron-rich nuclei.

Free Research Field

原子核（実験）