"Electron-captures on medium-heavy nuclei play an important role in the late evolution of core-collapse supernovae. Sensitivity studies of simulations of these supernovae indicate a region of nuclei near the N = 50 shell closure, just above doubly magic 78Ni, that have a significant effect on key characteristics of the evolution, such as the lepton fraction, electron fraction, entropy, stellar density and in-fall velocity. However, the vast majority of the nuclei in this region do not have dedicated weak-rate calculations; instead their rates are approximated via a method known for its overestimation of rates in heavy, neutron-rich nuclei. In order to guide the development of microphysical theoretical models, which yield Gamow-Teller strength distributions, from which more accurate electron-capture rates can be deduced, experimental data is needed to verify the validity of current models and to guide the development of improved models. Charge-exchange reactions at intermediate energies are an excellent tool with which to extract Gamow-Teller strength distributions model-independently, because of the well-established proportionality between the reaction cross section and the Gamow-Teller strength. In an attempt to obtain more accurate nuclear physics inputs for astrophysical simulations, an experimental campaign was performed at the National Superconducting Cyclotron Laboratory to study nuclei near the N = 50 shell closure. 86Kr lies immediately adjacent to the region of interest for core-collapse supernovae; it was probed using the (t,3He+gamma) with the S800 magnetic spectrometer and the gamma-detection array, GRETINA. The Gamow-Teller strength distribution, and the associated electron-capture rates, were extracted from the experimental data, to compare with theoretical models and to determine the validity of the current nuclear physics inputs for core-collapse supernova simulations."--Pages ii-iii.
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