Repulsive three-body force and channel-coupling effects via 12C+12C scattering at 100A MeV

The angular distributions of differential cross sections of C-12 + C-12 elastic and inelastic scattering populating the ground and excited states in C-12 up to 15 MeV excitation energy are precisely measured for the first time at an incident energy of 100A MeV to study the effect of repulsive three-body forces. Using the high-resolution spectrometer Grand Raiden at the Research Center for Nuclear Physics (RCNP), Osaka University, we have obtained the differential cross sections for the ground state (0(1)(+)) and 4.44 MeV (2(1)(+)) excited state, as well as the summed differential cross sections for the states between 4.44 and 15 MeV in the angular range of 1.0 degrees-7.5 degrees. The results are compared with microscopic coupled-channel calculations. The potential between the colliding nuclei is determined by the double folding method with three different complex G-matrix interactions, the ESC, CEG07b, and MPa interactions. The CEG07b and MPa interactions, which include repulsive three-body forces, describe the data well, whereas the ESC interaction, which does not include repulsive three-body forces, fails to reproduce the data. The results provide evidence of repulsive three-body forces in C-12 and demonstrate the possible sensitivity of elastic scattering to three-body forces.