Heavy Cluster Knockout Reaction 16O(12C,212C)4He and the Nature of the 12C-12C Interaction Potential

The heavy cluster knockout reaction 16O(12C,212C)4He performed for the first time, reveals the true nature of the 12C-12C interaction. The observed cross section is enhanced by almost 2 orders of magnitude over the conventional zero range distorted wave impulse approximation (DWIA) predictions. An attractive 12C-12C optical potential, as obtained in the folding model, does not explain the enhanced cross section in the finite range (FR) DWIA framework. The inclusion of a hard core of fairly long range ∼3.65 fm explains the data. The present investigation of 16O(12C,212C)4He along with the 12C-12C elastic scattering also proves beyond doubt that the folding model's deep attractive heavy ion potentials are unsuitable to describe the highly overlapping heavy ions. The application of FR-DWIA opens up new avenues to use the heavy core knockout for the detailed investigation of heavy as well as Borromean halo nuclei.