Fusionlike processes in theN14+232Th reaction at 30 MeV/nucleon

Abstract

Fusionlike processes were studied in the $^{14}\mathrm{N}$${+}^{232}$Th reaction at 30 MeV per nucleon. Partition of the fusionlike cross section was determined by detecting nonequilibrium charged particles with an array of phoswich detectors (plastic wall) in coincidence with fission fragments for which the folding angle and thus the momentum transfer was measured. By measuring both single and multiple hits in the plastic wall and by correcting for its incomplete angular coverage a very extensive database of the fusionlike channels was obtained. The results were compared with model predictions comprising the BUU, Fermi jetting, the Boltzmann master equation model, and the nucleon-exchange transport model. It was found that these models which globally describe the dependence of the inclusive momentum transfer in fusionlike reactions cannot account for the associated particle production, in particular if the nucleons bound in the observed complex particles (d,t,\ensuremath{\alpha}) are included in the comparison. Calculations of the energy spectra of the complex particles with the coalescence formalism indicate that a large fraction of the observed complex particles in the fusionlike reactions cannot be accounted for by pre-equilibrium emission from the fused composite system. They most probably originate from massive-transfer-type reactions that contribute to the beam-velocity component in the energy spectra.