Constraining the νp-process through the first direct measurement of the ⁵⁶Ni(n,p)⁵⁶Co reaction cross section at LANSCE

The rate of the ⁵⁶Ni(n,p)⁵⁶Co reaction is a critical input for understanding the synthesis of heavy elements through the νp-process. However, there currently exists no experimental data for the reaction. This is due to the technical difficulties of producing a quality neutron beam at the relevant energies and in the fabrication of a short-lived ⁵⁶Ni target (T_1/2 ≈ 6 days). We are leveraging a world unique capability that currently exists at LANSCE by producing the radioactive sample at the Isotope Production Facility (IPF) then performing the measurement using the well characterized beam of fast neutrons, spanning a broad energy range from 100s of keV to 100s of MeV, available at the WNR facility. Details on the target fabrication process, technical considerations for the experimental setup, and results of the ⁵⁶Ni(n,p)⁵⁶Co measurement will be presented. With the newly obtained experimental information, the reaction rate of ⁵⁶Ni(n,p) has been updated and compared with other theoretical predictions. The final impact on the νp process will be discussed along with a plan for improving the experimental uncertainty in future measurements using an optimized solenoidal spectrometer.