Speaker
Description
The existence of the intermediate neutron-capture process (i-process) explains the observed astrophysical abundances of elements around the Z<50 region [1]. Neutron capture reactions in the A=70 mass region for Ni, Cu, and Zn isotopes are known to produce large variations in predicted i-process abundances [1]. Predicted stellar abundances of Ga are particularly affected by the $^{69}$Zn(n,$\gamma$) reaction. The $\beta$-decay of $^{70}$Cu offers an opportunity utilize the $\beta$-Oslo method to experimentally determine the $\gamma$-strength function ($\gamma$SF) and nuclear level density (NLD) of $^{70}$Zn to constrain the $^{69}$Zn(n,$\gamma$) reaction rate for i-process nucleosynthesis. $^{70}$Cu has three different $\beta$-decaying spin-parity states that populate different spin ranges at similar excitation energies in the daughter nucleus: the 6$^-$ ground state, the 101 keV 3$^-$ isomeric state, and the 242 keV 1$^+$ isomeric state [2]. In an experiment performed at the National Superconducting Cyclotron Laboratory the three states of $^{70}$Cu was produced and delivered to the Summing NaI (SuN) Total Absorption Spectrometer [3]. Spectra from the $\beta$-decays of each state were isolated using different beam on/off periods. Preliminary results from $\beta$-Oslo analysis to obtain $\gamma$SF and nuclear level densities will be presented. The preliminary constrained $^{69}$Zn(n,$\gamma$)$^{70}$Zn reaction rate will also be presented.
[1] J. E. McKay et al. MNRAS 491, (2020) 5179-5187.
[2] P. Vingerhoets et al. Phys. Rev. C 82, 064311 (2010).
[3] A. Simon et al. Nucl. Inst. and Meth. Phys. Res. A 703, (2013) 16.
