Background: The C9 nucleus and related capture reaction, B8(p,γ)C9, have been intensively studied with an astrophysical interest. Due to the weakly bound nature of C9, its structure is likely to be described as the three-body (Be7+p+p). Its continuum structure is also important to describe reaction processes of C9, with which the reaction rate of the B8(p,γ)C9 process have been extracted indirectly. Purpose: We preform three-body calculations on C9 and discuss properties of its ground and low-lying states via breakup reactions. Methods: We employ the three-body model of C9 using the Gaussian-expansion method combined with the complex-scaling method. This model is implemented in the four-body version of the continuum-discretized coupled-channels method, by which breakup reactions of C9 are studied. The intrinsic spin of Be7 is disregarded. Results: By tuning a three-body interaction in the Hamiltonian of C9, we obtain the low-lying 2+ state with the resonant energy 0.781 MeV and the decay width 0.137 MeV, which is consistent with the available experimental information and a relatively high-lying second 2+ wider resonant state. Our calculation predicts also sole 0+ and three 1- resonant states. We discuss the role of these resonances in the elastic breakup cross section of C9 on Pb208 at 65 and 160 MeV/nucleon. Conclusions: The low-lying 2+ state is probed as a sharp peak of the breakup cross section, while the 1- states enhance the cross section around 3 MeV. Our calculations will further support the future and ongoing experimental campaigns for extracting astrophysical information and evaluating the two-proton removal cross sections.
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics