Reaction mechanisms in the 40Ar + 197Au collisions at 35 MeV/nucleon

Abstract

The fission fragment angular correlation has been measured in the Ar + Au reaction at 35 MeV/nucleon. Two components are clearly separated: the sequential fission of the target ( σ = 320 ± 80 mb) and a fusion-like process ( σ = 480 ± 120 mb). The linear momentum transfer per nucleon for the fusion-like events reaches the limitation of 190 MeV/ c observed in earlier studies. This limitation does not reflect a limit to the excitation energy that a nucleus can contain. Heavy residues with energies larger than 0.13 MeV nucleon have been measured in the forward region. This observation of residues with high excitation energies implies the existence of a competition between fission and evaporation at excitation energies as high as ∼800 MeV. Particles and light nuclei have been detected in a forward multidetector in coincidence with two fission fragments or a heavy residue.