β decay strength function for ^{53, 55}Ni and ^{52, 54}Co

Proton-rich nuclei in the universe are created by rp-process and the νp-process. This work deals with four nuclei relevant to the nucleosynthesis of the p-nuclei: ^52,54Co and ^53,55Ni. β+ decays for each isotope were recorded with the Summing NaI(Tl) detector¹ at the National Superconducting Cyclotron Laboratory. A preliminary β+ decay intensity function, Iβ+, was found for each isotope by utilizing Total Absorption Spectroscopy (TAS). A variety of experimental spectra (e.g TAS, Sum of Segments, Multiplicity, and pixelated surface barrier detector) were compared to GEANT4 simulations of the full detector setup based on information from the National Nuclear Data Center. An important feature in the measurement of ⁵³Ni is that protons from a β delayed proton decay were detected in the pixelated surface barrier detector and gave information on the strength to proton-unbound states. The measured spectra, when fitted with the simulated spectra, give the probability that a particular child level is populated during decay. Results, when compared to shell-model theory, will provide insight and help to improve the understanding of the formation of p-process elements.

1. Simon et. al Nucl. Instr. and Meth. A703, 16 (2013)