Impact ofO16(e,e′α)C12measurements o

Abstract

The 12 C(α, γ) 16 O reaction, an important component of stellar helium burning, has a key role in nuclear astrophysics. It has direct impact on the evolution and final state of massive stars and also influences the elemental abundances resulting from nucleosynthesis in such stars. Providing a reliable estimate for the energy dependence of this reaction at stellar helium burning temperatures has been a longstanding and important goal. In this work, we study the role of potential new measurements of the 16 O(e, e α) 12 C reaction in reducing the overall uncertainty. A multilevel R-matrix analysis is used to make extrapolations of the astrophysical S factor for the 12 C(α, γ) 16 O reaction to the stellar energy of 300 keV. The statistical precision of the S-factor extrapolation is determined by performing multiple fits to existing E 1 and E 2 ground state capture data, including the impact of possible future measurements of the 16 O(e, e α) 12 C reaction. In particular, we consider a proposed MIT experiment that would make use of a high-intensity low-energy electron beam that impinges on a windowless oxygen gas target as a means to determine the total E 1 and E 2 cross sections for this reaction.

Expanding Nuclear Physics Horizons with the Gamma Factory

“…There is a revived interest in studying this process at electron‐scattering facilities. [ 217,218 ] While one wins in the rates due to high intensity of electron sources, the price to pay are electromagnetic background processes and the necessity to extrapolate to the real photon point. At GSI, Coulomb dissociation of a 500 MeV per nucleon 16 O beam colliding with a Pb target is used to address this reaction.…”

The status and future of direct nuclear reaction measurements for stellar burning

“…= 1.0 MeV but also at higher energies. One advantage of measuring the 16 O(γ, α) 12 C reaction is the enhancement by a factor of 100 of the cross section with respect to the inverse 12 C(α, γ) 16 O process [66,290] at the same E c.m. .…”

Operation and characterization of a windowless gas jet target in high-intensity electron beams

“…Furhtermore, the study of reactions of astrophysical importance such as 16 O(e, e α) 12 C, where the α-particle is detected with a detector arrangement inside the scattering chamber, will become possible at unprecedented low center-of-mass energies [12,13].…”