Orateur
Description
The $^3$He$(\alpha,\gamma)^7$Be reaction is an important part of ongoing processes occurring in stars like our very own sun. In the fusion reaction network of the sun, the $^3$He$(\alpha,\gamma)^7$Be reaction is key to determining the $^7$Be and $^8$B neutrino fluxes resulting from the pp-II chain . In standard solar model (SSM) predictions of these neutrino fluxes, the low-energy $^3$He$(\alpha,\gamma)^7$Be $S$ factor, $S_{34}(E)$, is the largest source of uncertainty from nuclear input. The SSM uses $S_{34}(E)$ near the Gamow peak energy, roughly 18 keV, which cannot be experimentally measured since the Coulomb force between $^3$He and $^4$He suppresses the fusion reaction at such low energies. Theoretical calculations are needed to guide the extrapolation to the solar energies of interest. To this end, I will present ab initio calculations of the $^3$He$(\alpha,\gamma)^7$Be reaction using the no-core shell model with continuum starting from two- and three-nucleon chiral interactions. To demonstrate that the NCSMC provides an accurate $S$ factor, I will also compare NCSMC $^{3}$He + $^{4}$He elastic-scattering cross sections with those recently measured by the SONIK collaboration.
This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344. Lawrence Livermore National Security, LLC.
