Determination of S18 from 9C breakup reaction within a four-body reaction model
Abstract
The astrophysical factor S18 for the 8B(p,γ)9C has indirectly been measured with the proton removal reactions from 9C, elastic breakup of 9C off a heavy target, and transfer reactions. Quite recently, the elastic breakup cross section data were reanalyzed with the continuum-discretized coupled channels method (CDCC) assuming a p+ 8B two-body model for 9C and the S18 was modified. It was not well justified, however, to treat 8B as an inert nucleus given its proton separation energy is only 137~keV. We reexamine the elastic breakup of 9C by the four-body CDCC with a p+p+ 7Be three-body model for 9C and evaluate S18. To achieve this, we propose a method to disentangle the p+ 8B+ 208Pb three-body channel in the four-body CDCC calculation, for the first time. We calculate the elastic breakup cross section of 9C off a 208Pb target at 65~MeV/nucleon. The obtained breakup cross sections are decomposed into the contributions of the p+ 8B+ 208Pb and p+p+ 7Be+ 208Pb channels by using the solution of the complex-scaled Lippmann--Schwinger equation. The breakup cross section to the p+ 8B+ 208Pb channel reproduces well the shape of the experimental data in the low breakup energy region, which is important for determining S18. By fitting the theoretical result to the experimental data, the asymptotic normalization coefficient of 9C for the p+ 8B configuration is determined and we obtain S18=38.41.1 eVb. This result is smaller than the previous value obtained with the three-body CDCC by about 45\%. Thus, our new results suggest the necessity of taking into account the fragile nature of 8B in the 9C breakup.
Turn this paper into a full lesson
ArcXiv compiles a staged curriculum from this paper: 8-12 lessons across beginner → advanced, synthesised section guides, visuals, flashcards, a quiz, exercises, and on-demand deep dives per section. Grounded in the abstract, never invented.