First direct measurement of ${}^{59}$Cu(p,$\alpha$)${}^{56}$Ni: A step towards constraining the Ni-Cu cycle in the Cosmos

Abstract

Reactions on the proton-rich nuclides drive the nucleosynthesis in Core-Collapse Supernovae (CCSNe) and in X-ray bursts (XRBs). CCSNe eject the nucleosynthesis products to the interstellar medium and hence are a potential inventory of p-nuclei, whereas in XRBs nucleosynthesis powers the light curves. In both astrophysical sites the Ni-Cu cycle, which features a competition between ${}^{59}$Cu(p,$\alpha$)${}^{56}$Ni and ${}^{59}$Cu(p,$\gamma$)${}^{60}$Zn, could potentially halt the production of heavier elements. Here, we report the first direct measurement of ${}^{59}$Cu(p,$\alpha$)${}^{56}$Ni using a re-accelerated ${}^{59}$Cu beam and cryogenic solid hydrogen target. Our results show that the reaction proceeds predominantly to the ground state of ${}^{56}$Ni and the experimental rate has been found to be lower than Hauser-Feshbach-based statistical predictions. New results hint that the $\nu p$-process could operate at higher temperatures than previously inferred and therefore remains a viable site for synthesizing the heavier elements.

References in corpus (11)

• Origin of the heavy elements in binary neutron-star mergers from a gravitational wave event
• A kilonova as the electromagnetic counterpart to a gravitational-wave source
• Production of Light Element Primary Process nuclei in neutrino-driven winds
• Dependence of X-Ray Burst Models on Nuclear Reaction Rates
• Further explorations of the alpha-particle optical model potential at low energies for the mass range A=45-209
• Successful prediction of total $\alpha$-induced reaction cross sections at astrophysically relevant sub-Coulomb energies using a novel approach
• The nuclear force imprints revealed on the elastic scattering of protons with ${}^{10}$C
• Direct study of the alpha-nucleus optical potential at astrophysical energies using the 64Zn(p,alpha)61Cu reaction
• Observation of excited states in ${}^{20}$Mg sheds light on nuclear forces and shell evolution
• Consistent optical potential for incident and emitted low-energy $\alpha$ particles. II. $\alpha$-emission in fast-neutron induced reactions on Zr isotopes
• Determination of the ${}^{60}$Zn level density from neutron evaporation spectra

Cited by in corpus (2)

• Extension of the particle x-ray coincidence technique: The lifetimes and branching ratios apparatus
• Charged-particle optical potentials tested by first direct measurement of 59Cu(p,alpha)56Ni reaction