The role of light-particle emission in fusion-like reactions between 40Ar+ 40Ca at 20 MeV/u

Abstract

Heavy reaction products resulting from central collisions in the mass-symmetric system 40Ar+ 40Ca were studied at an incident energy of 20 MeV/u. The data allow for a separation between evaporation residues produced in central collisions and fragments from more peripheral reactions. The velocity distributions of individual masses are analyzed and a mass spectrum of evaporation residues is extracted. A statistical model is presented which accounts well for the mass distributions obtained at 20 MeV/u as well as at lower bombarding energies. The resulting branching ratios are consistent with experimentally deduced nucleon and light charged particle multiplicities. The mass difference between the observed fragments and the compound system can be explained entirely by the emission of light particles with Z ≤ 2.