Light particle emission in the reaction 144Sm(32S, fission) at Elab=838 MeV.

Abstract

Energy spectra of light charged particles have been measured in coincidence with fissionlike fragments using the 4\ensuremath{\pi} charged-particle detector AMPHORA. Preequilibrium, prescission, and postscission components of emitted protons, deuterons, and alphas have been extracted from the energy spectra using a multiple source fit procedure. Including previously measured exclusive neutrons, a complete data set for light particle emission from the system $^{144}\mathrm{Sm}$${+}^{32}$S(26A MeV) is now available. Mass and excitation energy of an equilibrated composite system has been defined by application of the massive transfer model using multiplicities and apparent temperatures of the preequilibrium components. The results have been compared to statistical model computations. A fair overall agreement is observed for different parametrizations of the Fermi-gas level-density parameter with indications for a decrease of the level density parameter with increasing nuclear temperature. The correlations between slope parameter, prescission, and total particle multiplicity turned out to be a sensitive probe for the level density parameter. In the energy spectra of alpha particles a low-energy component has been observed with strong focusing into directions perpendicular to the fission axis.