The heavy cluster knockout reaction ${}^{16}\mathrm{O}({}^{12}\mathrm{C},2{}^{12}\mathrm{C}){}^4\mathrm{He}$ performed for the first time, reveals the true nature of the ${}^{12}\mathrm{C}\mathrm{\text{−}}{}^{12}\mathrm{C}$ 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 ${}^{12}\mathrm{C}\mathrm{\text{−}}{}^{12}\mathrm{C}$ 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 $\sim 3.65\mathrm{fm}$ explains the data. The present investigation of ${}^{16}\mathrm{O}({}^{12}\mathrm{C},2{}^{12}\mathrm{C}){}^4\mathrm{He}$ along with the ${}^{12}\mathrm{C}\mathrm{\text{−}}{}^{12}\mathrm{C}$ 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.

• Received 25 October 2010

DOI:https://doi.org/10.1103/PhysRevLett.106.022501