Limitation of the fusion cross section for the 12C+11B system at Ec.m.=36.5 and 41.7 MeV.

Abstract

Inclusive spectra of protons, \ensuremath{\alpha} particles, and heavy ejectiles as well as coincidence spectra of protons and \ensuremath{\alpha} particles with heavy ejectiles were measured for $^{12}\mathrm{C}$${+}^{11}$B system at several angles and at two laborabory energies of $^{11}\mathrm{B}$: 70 and 80 MeV. A Hauser-Feshbach model analysis was performed for inclusive and coincidence spectra to extract the fusion cross section values 800 \ifmmode\pm\else\textpm\fi{} 50 mb and 750 \ifmmode\pm\else\textpm\fi{} 50 mb at ${\mathit{E}}_{\mathrm{lab}}$ 70 and 80 MeV, respectively. These values are in agreement with the limitation of the fusion imposed by entrance channel conditions and by properties of the compound nucleus, in contradiction to results of earlier investigations which suggested an anomalous energy dependence of the fusion. \textcopyright{} 1996 The American Physical Society.