Search for cluster effects in p+12C elastic scattering by a diffractional method

We investigate medium-energy angular distribution data of proton elastic scattering on C-12, with the aim to probe the existence of cluster distributions in the ground state of C-12. In our approach, we exploit Coupled-channel calculations to describe the scattering from a spheroidal-like structure, and we include a further contribution, based on a diffraction scattering formula, to explicitly take into account a possible triangular alpha-cluster structure of the target. From the present analysis, we find a quite small cluster component in C-12 ground state (with an upper limit on the occurrence probability of 1%, 99.75% confidence level) and an inter-cluster distance of similar or equal to 3.9 fm. These values are compared with several theoretical predictions reported in the literature.