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Neutrons emitted by targetlike fragments after the inelastic reactions of 154 MeV $^{32}\mathrm{S}$ on $^{100}\mathrm{Mo}$ have been measured. Neutron energy spectra and multiplicities have been derived as a function of the dissipated energy for targetlike fragment mass bins ${A}_{\mathrm{TL}}$=96\char21{}98, 101\char21{}103, and 104\char21{}106 and have been compared with the results of a Monte Carlo simulation which performs statistical model calculations of the targetlike fragment decay, with different assumptions on the partition of the excitation energy between the reaction partners. The partition following an equal temperature hypothesis better describes the experimental data but a sizable influence of the exit channel is found on the experimental neutron multiplicity.

We discuss the evidence of dynamical mean field effects in medium energy peripheral fragmentation through the excitation of collective motions, mostly of isoscalar giant quadrupole resonance type, in the colliding ions before fragmentation. From an analysis of the dissipative tail in the fragment energy spectra we deduce the mean number of excited phonons at the moment of fragmentation. Since giant resonances have a very peculiar structure in momentum space we can establish a definite correlation between the dissipative part of the energy spectra and the behavior of parallel and orthogonal momentum widths of emitted fragments. Everything can be consistently evaluated without free parameters, and we finally get a thorough understanding of several unexplained features of projectile fragmentation in medium energy heavy-ion collisions. Detailed analysis of the reactions /sup 40/Ar+/sup 27/Al,/sup nat/Ti at 44 MeV/nucleon is shown.