Elucidation of the r-process second peak from key nuclear mass measurements at N=82 with the Rare-RI Ring at RIKEN/RIBF

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K03901
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 15020:Experimental studies related to particle-, nuclear-, cosmic ray and astro-physics
• Research Institution: Institute of Physical and Chemical Research
• Principal Investigator: NAIMI SARAH 国立研究開発法人理化学研究所, 開拓研究本部, 研究員 (40747135)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: nuclear mass / storage ring / r-process / position detector

Outline of Final Research Achievements

Mass measurement of rare isotope 123Pd produced at RIBF/ RIKEN was performed with the Rare-RI Ring. The mass of this isotope was used to perform astrophysical calculation to estimate the r-process abundances of mass A=122 and A=123. We find that the abundance ratio of these two masses can be reproduced when using the new mass of 123Pd in the calculation.

We have also finalized the development of a new position-sensitive detector for the Rare-RI Ring. The detector position resolution is similar to that of the RIBF standard detector, with the advantage of being operable under the high-vacuum condition in the Rare-RI Ring.

Free Research Field

Nuclear astrophysics

Academic Significance and Societal Importance of the Research Achievements

Mass measurements of 123Pd was performed to investigate its influence in the r-process synthesis of chemical elements tin and antimony. Such measurement is only possible only at RIBF/RIKEN.
The results of this experiment was published in international journal and a press release was prepared.