First measurement in the Gamow window of a reaction for the γ-process in inverse kinematics: 76Se(α,γ)80Kr

J Fallis,C Akers,A.M Laird,A Simon,A Spyrou,G Christian,D Connolly,U Hager,D.A Hutcheon,A Lennarz,P O'Malley,S.J Quinn,J Riley,A Rojas,C Ruiz,M Williams

doi:10.1016/j.physletb.2020.135575

Abstract

The p-nuclei are the few stable nuclei heavier than iron on the neutron-deficient side of the valley of stability that cannot be produced through astrophysical neutron-capture reactions. The limited experimental data on reactions through which the p-nuclei might be produced leaves the origin of their production largely unknown. This work presents the first cross section measurements of the 76Se(α,γ)80Kr reaction. The rate of the time reversed reaction, 80Kr(γ,α)76Se, is one of the most uncertain of possible reactions which can occur at the 80Kr branching point on the γ-process photo-disintegration pathway. The reaction flow through 80Kr will directly affect the final abundance of the p-nuclide 78Kr. Experimental cross sections at two astrophysically relevant energies are reported and compared to cross sections calculated using Hauser-Feshbach codes talys, non-smoker, and smaragd. The success of these first (α,γ) cross section measurements performed in inverse kinematics in the energy region of the γ-process opens the door for future studies of reactions on radioactive γ-process nuclides.

Highlights

Very few of the reactions relevant to the ferentially pumped gas target; (ii) a high-supression γ-process have been studied experimentally and, two-stage separator; and (iii) a recoil detector sys-
Mary’s University, Halifax, Nova Scotia B3H 3C3, models with metallicity-dependent core collapse supernovae yields to investigate the contributions of Canada those various sites to the solar abundances of the
Michigan State University, East Lansing, Michigan 48824, USA 5Present address: Department of Physics, University of nuclei production was a supernova shock-front passing through the O-Ne layer of a massive star un

Summary

Introduction

Very few of the reactions relevant to the ferentially pumped gas target; (ii) a high-supression γ-process have been studied experimentally and, two-stage separator; and (iii) a recoil detector sys- Given that DRAGON was designed 185 detected in the silicon detectors could subseto study explosive nucleosynthesis with beams of quently be used to calculate the number of incident To determine the experimental recoil yield per incident ion (Y ) at each energy, the total number of in Ec.m. of 12 keV due to uncertainty in the SRIM data and target thickness.

Results

Conclusion