Proton capture cross section of Ge-72 and astrophysical implications

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This work was supported by the National Science Foundation under Grants No. PHY 1102511 (NSCL), No. PHY 1350234 (CAREER), No. 1430152 (JINA-CEE), and No. PHY 1306074.


This paper reports on the first cross section measurement of the Ge-72(p, gamma)As-73 reaction. The proton capture reaction on Ge-72 is relevant to the astrophysical p-process and was identified in a sensitivity study as one of the important reactions required to estimate the abundances of the light p nuclei. The gamma-summing technique was employed using the summing NaI(Tl) detector (SuN) from the National Superconducting Cyclotron Laboratory. The experiment was performed at the University of Notre Dame using a 1.8-3.6 MeV proton beam. In order to test the predictive power of different theoretical calculations in the region, experimental values were compared to the results given by the nuclear reaction code TALYS1.6. The theoretical uncertainties in the cross section arising from different combinations of nuclear level densities, gamma-ray strength functions, and optical model potentials were reduced to 10-18% by the experimental data. The recommended reaction rates from the standard astrophysical libraries, BRUSLIB and REACLIB, are found to be in good agreement with the experimental results.