Study for s-process using neutron beam provided from ANNRI of J-PARC

T Hayakawa ,Hideo Harada,Akira Kimura,Yosuke Toh,T Shizuma ,Shôji Nakamura

doi:10.1051/epjconf/201612205003

Abstract

Most isotopes heavier than iron are synthesized by the slow neutron capture reaction process (s-process) in stars. Isomers in stable isotopes have sometimes an important role as a branching point in nucleosynthesis flow in the s-process. An isomer with a half-life of 14.1 y in 113 Cd is a branching point from which a nucleosynthesis flow reaches to a rare isotope 115 Sn. The astrophysical origin of 115 Sn has remained still an open question. The s-process abundance of 115 Sn depends on the ratio of the 112 Cd(n, γ ) 113 Cd m reaction cross section to the 112 Cd(n, γ ) 113 Cd gs reaction cross section. However, the isomer production ratio following the neutron capture reaction has not been measured in the energy region higher than the thermal energy. An intense neutron beam experimental system, ANNRI, in J-PARC has a high purity germanium (HPGe) detector system consisting of two cluster detectors. We have measured γ -rays decaying to the ground state and the isomer using the HPGe detectors in conjunction with a time-offlight method at ANNRI.

Highlights

Nuclides heavier than iron were predominantly synthesized by two stellar neutron induced reactions of slow neutron capture reactions (s-process) and rapid neutron capture reaction process (r-process)
In the present experiment, we measured relative ratios of γ-rays decaying to the ground state to that to the isomer using the high purity germanium (HPGe) detectors
In the thermal energy region, the large peak originated from 113Cd is observed

Summary

Introduction

Nuclides heavier than iron were predominantly synthesized by two stellar neutron induced reactions of slow neutron capture reactions (s-process) and rapid neutron capture reaction process (r-process). Isomers in stable isotopes have sometimes an important role as a branching point in nucleosynthesis flow in the s-process The neutron capture reaction cross-sections were systematically measured and the resonance parameters were evaluated [6].

Results

Conclusion