Survival of orbiting inNe20(7–10 MeV/nucleon) +C12reactions

Abstract

The inclusive energy distributions of fragments with Z $\ensuremath{\ge}$ 3 emitted from the bombardment of $^{12}\mathrm{C}$ by $^{20}\mathrm{Ne}$ beams with incident energies between 145 and 200 MeV have been measured in the angular range ${\ensuremath{\theta}}_{\mathrm{lab}}~{10}^{\ifmmode^\circ\else\textdegree\fi{}}\text{\ensuremath{-}}{50}^{\ifmmode^\circ\else\textdegree\fi{}}$. Damped fragment yields in all cases have been found to be characteristic of emission from fully energy equilibrated composites; for B and C fragments, average Q values, $\ensuremath{\langle}Q\ensuremath{\rangle}$, were independent of the center-of-mass emission angle (${\ensuremath{\theta}}_{\mathrm{c.m}.}$), and the angular distributions followed a $~1/\mathrm{sin}{\ensuremath{\theta}}_{\mathrm{c.m}.}$-like variation, signifying long lifetimes of the emitting dinuclear systems. Estimates of total yields of these fragments have been found to be much larger than those predicted by the standard statistical model. This may be indicative of the survival of an orbiting-like process in the $^{12}\mathrm{C}+^{20}\mathrm{Ne}$ system at these energies.