Ni cross section

The merger of two neutron stars was recently observed in a combination of gravitational and electromagnetic radiation.  The time profile of the electromagnetic signature of the merger event confirmed that an r-process event had taken place, identifying neutron-star mergers as at least one site for the astrophysical r-process.  The neutron-capture cross sections of the neutron-rich nuclei needed to inform r-process abundance predictions in neutron-star merger scenarios are poorly known and must be constrained through indirect techniques.  One indirect technique, the β-Oslo method, extracts the nuclear level density (NLD) and γ-ray strength function (γSF) following beta decay and uses these two quantities in a Hauser-Feshbach calculation to constrain the neutron capture cross section.  The β-Oslo method has been used previously to obtain experimentally-constrained neutron-capture cross sections of ^68,69Ni. An experiment at the National Superconducting Cyclotron Laboratory measured the β-delayed γ rays of nuclei in the A~70 region to extract NLD and γSFs of neutron-rich nuclei. Results for ⁷⁰Ni(n,γ)⁷¹Ni will be presented and the statistical properties and neutron-capture cross section will be compared to those of the lighter nickel isotopes.