R. Lewis

Experimental Neutron Capture Rate Constraint Far from Stability

Nuclear reactions where an exotic nucleus captures a neutron are critical for a wide variety of applications, from energy production and national security, to astrophysical processes, and nucleosynthesis. Neutron capture rates are well constrained near stable isotopes where experimental data are available; however, moving far from the valley of stability, uncertainties grow by orders of magnitude. This is due to the complete lack of experimental constraints, as the direct measurement of a neutron-capture reaction on a short-lived nucleus is extremely challenging. Here, we report on the first experimental extraction of a neutron capture reaction rate on ^{69}Ni, a nucleus that is five neutrons away from the last stable isotope of Ni. The implications of this measurement on nucleosynthesis around mass 70 are discussed, and the impact of similar future measurements on the understanding of the origin of the heavy elements in the cosmos is presented.

Enhanced low-energy γ-decay strength of Ni70 and its robustness within the shell model

Neutron-capture reactions on very neutron-rich nuclei are essential for heavy-element nucleosynthesis through the rapid neutron-capture process, now shown to take place in neutron-star merger events. For these exotic nuclei, radiative neutron capture is extremely sensitive to their

Novel Techniques for Constraining Neutron-Capture Rates Relevant to Heavy-element Nucleosynthesis

\gamma

New low-energy 0 + state and shape coexistence in Ni 70

-emission probability at very low

Strong neutron-γ competition above the neutron threshold in the decay of Co70

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Neutron-capture rates for explosive nucleosynthesis: the case of 68Ni(n, γ)69Ni

energies. In this work, we present measurements of the

Shape coexistence from lifetime and branching-ratio measurements in 68,70Ni

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Nuclear Astrophysics with Radioactive Beams

-decay strength of

Constraining the cross section of

^{70}

^{82}

Ni over the wide range