Impact parameter dependence of light charged particle production in25A MeV 16Oon Tb, Ta, and Au and35A MeV 14Non Sm and Ta

Abstract

The impact parameter dependence of light charged particle $(p,d,t,\ensuremath{\alpha})$ emission has been studied using an impact parameter selection based on coincident detection of residues or fission fragments. The energy spectra at twelve angles between $20\ifmmode^\circ\else\textdegree\fi{}$ and $150\ifmmode^\circ\else\textdegree\fi{}$ have been fit by a multiple moving source parametrization. The angle and energy integrated preequilibrium proton multiplicities decrease with increasing impact parameter in qualitative agreement with a Fermi jet calculation. The preequilibrium $d/p$ and $t/p$ multiplicities increase slowly with increasing impact parameter and are nearly identical at the two bombarding energies. The preequilibrium $\ensuremath{\alpha}/p$ ratio shows a less consistent dependency on impact parameter but decreases significantly with increasing bombardment energy. A calculation of the $d/p$ and $t/p$ multiplicity ratios with a transport model incorporating complex particle emission is quite successful in reproducing the absolute magnitude, impact parameter dependence, and bombarding energy dependence of the experimental total multiplicities.