Impact of the β-Delayed Neutron Emission Probabilities Around A = 100–125 on the r-Process and the BRIKEN Project

Abstract

Recent observations of metal-poor Eu-enriched stars show large deviations in the abundance pattern of light elements with Z≤47 suggesting the existence of a second type of r-process, called weak r-process, which has occurred besides the more robust main r-process. It is believed that Ag and Pd, the heaviest among light r-process elements, may help reveal the nature of the weak r-process. We present a sensitivity studies to clarify the role of the β-delayed neutron emission probabilities (Pn values) in shaping the final elemental abundance of Ag and Pd. We show that the uncertainty on the calculated abundance of those elements caused by the unknown Pn values is comparable with the their abundance deviations from star to star. The BRIKEN project, an experimental program at RIBF, has been proposed to study the beta decay properties of the nuclei relevant to the r-process. A brief introduction about the experimental setup will be presented.