Constraining the Astrophysical γ Process: Cross Section Measurement of the ⁸²Kr(p,γ)⁸³Rb Reaction in Inverse Kinematics

The astrophysical γ process is considered to be the main production mechanism of a small group of proton-rich isotopes, the p nuclei. This mechanism consists of the “burning” of preexisting r- and s-process seeds, through a series of photodisintegration reactions. The astrophysical site where such high temperature conditions are fulfilled is not yet clearly identified. Networks of nuclear reactions are simulated under appropriate astrophysical conditions in order to reproduce the p-nuclei abundances observed in nature. However, as experimental cross sections of γ-process reactions are largely unknown, the related reaction rates are based entirely on HF theoretical calculations and thus carry large uncertainties. For this purpose the total cross section of the ⁸²Kr(p,γ)⁸³Rb reaction has been measured at incident energies between 3.1 and 3.7 MeV. The experiment took place at the NSCL at MSU, where the ⁸²Kr beam was directed onto a hydrogen gas cell in the center of the Summing NaI(Tl) detector. Results on the spectra obtained using the γ-summing technique and the extracted cross section will be presented along with its comparison to theoretical calculations using the NON-SMOKER and TALYS codes for various inputs of nuclear level density and γ-ray strength function.