Machine-Learning-Enabled Measurements of Astrophysical (p,n) Reactions with the SECAR Recoil Separator

Abstract

The synthesis of heavy elements in supernovae is affected by low-energy (n,p) and (p,n) reactions on unstable nuclei, yet experimental data on such reaction rates are scarce. The SECAR (SEparator for CApture Reactions) recoil separator at FRIB (Facility for Rare Isotope Beams) was originally designed to measure astrophysical reactions that change the mass of a nucleus significantly. We used a novel approach that integrates machine learning with ion-optical simulations to find an ion-optical solution for the separator that enables the measurement of (p,n) reactions, despite the reaction leaving the mass of the nucleus nearly unchanged. A new measurement of the ${}^{58}$Fe(p,n)${}^{58}$Co reaction in inverse kinematics with a 3.66$\pm$0.12 MeV/nucleon ${}^{58}$Fe beam (corresponding to 3.69$\pm$0.12 MeV proton energy in normal kinematics) yielded a cross-section of 20.3$\pm$6.3 mb and served as a benchmark for the new technique demonstrating its effectiveness in achieving the required performance criteria. This novel approach marks a significant advancement in experimental nuclear astrophysics, as it paves the way for studying astrophysically important (p,n) reactions on unstable nuclei produced at FRIB.

References in corpus (20)

• Astrophysical Reaction Rates From Statistical Model Calculations
• Neutrino-induced nucleosynthesis of A>64 nuclei: The nu p-process
• Tables of Nuclear Cross Sections and Reaction Rates: an Addendum to the Paper "Astrophysical Reaction Rates from Statistical Model Calculations"
• Asymmetries in core-collapse supernovae from maps of radioactive ${}^{44}$Ti in CassiopeiaA
• Nucleosynthesis in Early Supernova Winds II: The Role of Neutrinos
• The rp-Process in Neutrino-driven Winds
• Neutrino-driven wind simulations and nucleosynthesis of heavy elements
• Uncertainties in the nu p-process: supernova dynamics versus nuclear physics
• Hard X-ray emission lines from the decay of Ti-44 in the remnant of supernova 1987A
• Trends in Ti44 and Ni56 from Core-Collapse Supernovae
• Nuclear Reactions Rates Governing the Nucleosynthesis of Ti44
• Radioactive Scandium in the Youngest Galactic Supernova Remnant G1.9+0.3
• Neutrino signal from proto-neutron star evolution: Effects of opacities from charged-current-neutrino interactions and inverse neutron decay
• Proto-neutron star evolution with improved charged-current neutrino-nucleon interactions
• Uncertainties in $\nu$p-process nucleosynthesis from Monte Carlo variation of reaction rates
• The Nucleosynthetic Yields of Core-Collapse Supernovae, prospects for the Next Generation of Gamma-Ray Astronomy
• Reaction Rate Sensitivity of the Production of $\gamma$-ray Emitting Isotopes in Core-Collapse Supernova
• Sensitivity of ${}^{44}$Ti and ${}^{56}$Ni production in CCSN shock-driven nucleosynthesis to reaction rates
• Constraining the destruction rate of ${}^{40}$K in stellar nucleosynthesis through the study of the ${}^{40}$Ar(p,n)${}^{40}$K reaction
• A technique for the study of (p,n) reactions with unstable isotopes at energies relevant to astrophysics