^62,63,68,69Zn γ-Decay Probabilities for Surrogate Constraint of Neutron Capture Cross Sections

The surrogate method is an indirect technique used to constrain cross sections of nuclear reactions inaccessible for direct measurement. This method uses an alternate reaction channel to populate a nucleus of interest, combining resulting experimental data with theory to constrain the (n,γ) cross section. Hauser-Feshbach calculations use statistical nuclear models of the desired and surrogate reactions to predict cross sections from nuclear level densities, optical model potentials, and γ-strength functions (γSF). Individual γ-decay probabilities are experimentally extracted and used to constrain γSF models and therefore the resulting n-capture cross sections. The surrogate and n-capture reaction channels each populate the excited nucleus with a different spin-parity distribution, necessitating sampling a variety of spin states to correct for this difference.

This work presents γ-decay probabilities around the relevant neutron separation energies for four Zn isotopes. Reactions measured are ^64,70Zn(p,d) and ^64,70Zn(p,t) as surrogates for ^61,62,67,68Zn(n,γ). Experimental data was collected in 2021 at Texas A&M University with a 27-MeV proton beam and Hyperion, a particle-γ coincidence array utilizing in-beam γ-ray spectroscopy. This presentation will examine notable features of the extracted γ-decays and discuss possible implications for the neutron capture cross sections.