A Gateway to Astrophysically Important (n,p) Reactions*

To understand the role of np-process in production of p-nuclei in the neutrino driven winds of core-collapse supernova, the cross sections of key (n,p) nuclear reactions are particularly important [1]. A small variation in cross sections of these reactions brings about a significant difference in the abundance distribution of p-nuclei [1]. However, there are several uncertainties in the cross sections of these reactions, and the sensitivity studies rely on theoretically calculated cross sections. The direct experimental measurement of (n,p) cross sections on short-lived exotic nuclei is extremely challenging. Because of this, an indirect reaction measurement technique, called the Surrogate Reaction Method (SRM) [2], is being expanded to extract cross sections of (n,p) reactions. Using stable ⁹⁶Mo target, the ⁹⁶Mo(p,p`g) measurement was performed with a 20.97 MeV proton beam using the GODDESS (GRETINA-ORRUBA: Dual Detectors for Experimental Structure Studies) detection system at ATLAS to utilize the (p,p`) reaction as a surrogate for the (n,p) reaction. The experimental details and preliminary results will be presented.

[1] S. Wanajo, H-T. Janka, and S. Kubono, The Astrophysical Journal 729, 46 (2011)

[2] J.E. Escher et al., Rev. Mod. Phys. 84, 353 (2012)