Heavy Cluster Knockout Reaction {sup 16}O({sup 12}C,2{sup 12}C){sup 4}He and the Nature of the {sup 12}C-{sup 12}C Interaction Potential

The heavy cluster knockout reaction {sup 16}O({sup 12}C,2{sup 12}C){sup 4}He performed for the first time, reveals the true nature of the {sup 12}C-{sup 12}C 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 {sup 12}C-{sup 12}C 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 {approx}3.65 fm explains the data. The present investigation of {sup 16}O({sup 12}C,2{sup 12}C){sup 4}He along with the {sup 12}C-{sup 12}C 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.