Equilibrium and Pre-equilibrium Neutron Emission in Dissipative ^112Sn + ^40,48Ca Reactions at E_lab/A = 35MeV.

Exclusive measurements of neutrons, light charged particles(LCP) and intermediate-mass fragments(IMF) from the reactions ^112Sn + ^40Ca and ^112Sn + ^48Ca at E_lab/A = 35MeV have been performed in coincidence with massive projectile-like fragments(PLF). Emission patterns of neutrons, reconstructed from the measured neutron velocities have been analysed in terms of statistical emission from different moving sources. These patterns are inconsistent with a scenario of two equilibrated PLF and TLF emitters . An additional high-energy neutron component is observed with a logarithmic spectral slope of approximately 10-15 MeV attributed to pre-equilibrium processes. The average multiplicity of neutrons emitted from PLF sources for the two reactions studied, correlates strongly with the number of neutrons available in the entrance channel. This work is supported by the U.S. DOE under grant number DE-FG02-88ER40414