Informing direct neutron capture on tin isotopes near the N=82 shell closure

Half of the elements heavier than iron are believed to be produced through the rapid neutron-capture process (r process). The astrophysical environment(s) where the r process occurs remains an open question, even after recent observations of neutron-star mergers and the associated kilonova. Features in the abundance pattern of r-process ashes may provide critical insight for distinguishing contributions from different possible sites, including neutron-star mergers and core-collapse supernovae. In particular, the largely unknown neutron-capture reaction rates on neutron-rich unstable nuclei near Sn-132 could have a significant impact on the final r-process abundances. To better determine these neutron-capture rates, the (d, p) reaction has been measured in inverse kinematics using radioactive ion beams of Sn-126 and Sn-128 and a stable beam of Sn-124 interacting with a (CD2)(n) target. An array of position-sensitive silicon strip detectors, including the Super Oak Ridge Rutgers University Barrel Array, was used to detect light reaction products. In addition to the present measurements, previous measurements of Sn-130,Sn-132(d, p) were reanalyzed using state-of-the-art reaction theory to extract a consistent set of spectroscopic factors for (d, p) reactions on even tin nuclei between the heaviest stable isotope Sn-124 and doubly magic Sn-132. The spectroscopic information was used to calculate direct-semidirect (n,gamma) cross sections, which will serve as important input for r -process abundance calculations.