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Formation and decay of hot nuclei have been studied in Zn-64 + Ti-nat collisions between 35 and 79 MeV/nucleon. The mass and excitation energy of excited quasiprojectiles are reconstructed from the kinematical characteristics of their decay products. In central collisions, excitation energies larger than 10 MeV/nucleon are reached. Comparisons with theoretical predictions indicate that a fraction of the excitation energy is associated with an isotropic radial flow.

Azimuthal distributions of helium ions have been measured in coincidence with high-energy protons in reactions induced by {sup 16}O at 94 MeV/nucleon on {sup 27}Al, {sup 58}Ni, and {sup 197}Au. Helium ions have been detected in a large area multidetector. Protons have been observed at 90{degree}. Mean multiplicities of light charged particles (H and He) are found slightly dependent on the target mass. Strong azimuthal asymmetries whose intensity is larger for the Al target and vanishes with the increasing of the target mass are observed in the He distributions. Experimental data are discussed in the framework of the participant-spectator picture of a modified fireball model, taking into account intermediate energy corrections. In this framework the behavior of the azimuthal asymmetries, as a function of the target mass, indicates a strong final-state interaction between participant and spectator fragments. Such a result is found in agreement with interaction time predictions of a microscopical calculation based on the Boltzmann-Nordheim-Vlasov equation.

Protons and charged pions have been detected at 70\ifmmode^\circ\else\textdegree\fi{}, 90\ifmmode^\circ\else\textdegree\fi{}, and 120\ifmmode^\circ\else\textdegree\fi{} in the reaction induced by $^{16}\mathrm{O}$ on various targets at 94 MeV/nucleon incident energy. Measured energy spectra are analyzed in terms of statistical emission from equilibrated sources in a participant-spectator picture. Microscopic dynamical calculations based on the Boltzmann-Nordheim-Vlasov equation are also performed. Experimental data are well reproduced by both models.

Reaction mechanisms and multifragmentation processes have been studied for Zn-64 + Ni-58 collisions at intermediate energies with the help of antisymmetrized molecular dynamics (AMD-V) model calculations. Experimental energy spectra, angular distributions, charge distributions, and isotope distributions, classified by their associated charged particle multiplicities, are compared with the results of the AMD-V calculations. In general the experimental results are reasonably well reproduced by the calculations. The multifragmentation observed experimentally at all incident energies is also reproduced by the AMD-V calculations. A detailed study of AMD-V events reveals that, in nucleon transport, the reaction shows some transparency, whereas in energy transport the reaction is much less transparent at all incident energies studied here. The transparency in the nucleon transport indicates that. even for central collisions, about 75% of the projectile nucleons appear in the forward direction. In energy transport about 80% of the initial kinetic energy of the projectile in the center-of-mass frame is dissipated. The detailed study of AMD-V events also elucidates the: dynamics of the multifragmentation process. The study suggests that, at 35A MeV, the semitransparency and thermal expansion are the dominant mechanisms for the multifragmentation process, whereas at 49A MeV and higher incident energies a nuclear compression occurs at an early stage of the reaction and plays an important role in the multifragmentation process in addition to that of the thermal expansion and the semitransparency.

Two-particle correlations at small relative momenta were measured for /sup 16/O-induced reactions on /sup 197/Au at E/A = 94 MeV, providing information about the space-time localization and excitation energy density of the emitting system. Two-particle correlation functions suggest that emission occurs from a region which is slightly larger than observed for /sup 14/N-induced reactions at E/A = 35 MeV, but significantly smaller than for /sup 40/Ar-induced reactions at E/A = 60 MeV. In contrast, the relative populations of widely separated particle unbound states are found to be surprisingly independent of incident energy and projectile mass.

Two-particle correlations at small relative momenta provide information about the space-time extent and the excitation energy density of the emitting system. Detailed measurements of two-particle correlations were performed for $^{40}\mathrm{induced}$ reactions on $^{197}\mathrm{Au}$ at E/A=60 MeV. In general, more pronounced correlations are measured for particles of higher outgoing energy. From the relative populations of excited states, a mean emission temperature of T\ensuremath{\approxeq}5.5 MeV is extracted. Within the framework of the quantum statistical model, our findings are consistent with an expanding nuclear system which disintegrates at low temperature (T\ensuremath{\approxeq}5.5 MeV) and rather low density (\ensuremath{\rho}\ensuremath{\le}0.1${\ensuremath{\rho}}_{0}$).

The inclusive inelastic scattering of \ensuremath{\alpha} particles on $^{2}\mathrm{H}$, $^{3}\mathrm{He}$, and $^{4}\mathrm{He}$ has been measured at 7.0 GeV/c incident momentum, between 2\ifmmode^\circ\else\textdegree\fi{} and 15\ifmmode^\circ\else\textdegree\fi{} in the laboratory. The momentum spectra of the recoiling \ensuremath{\alpha} particles are richly structured, suggesting that scattering takes place, at least partially, on nuclear substructures. The differential cross sections for the three reactions show a diffractive behavior comparable to that of the corresponding elastic processes.

Correlations between coincident alpha particles and deuterons emitted in /sup 40/Ar-induced reactions on /sup 197/Au at E/A = 60 MeV were measured. The relative populations of particle-unstable states of /sup 6/Li were extracted. The measured spectra are consistent with a mean nuclear temperature at emission of T = 5 MeV. Limitations of temperature measurements via the population of excited states are discussed.

We present a complete set of eight differential cross sections of the reactions $^{2}\mathrm{H}(d, n)^{3}\mathrm{He}$ and $^{2}\mathrm{H}(d, p)^{3}\mathrm{H}$ in the 0-60\ifmmode^\circ\else\textdegree\fi{} c.m. angular range for incident deuteron momenta between 1.1 and 2.5 GeV/c. A simple phenomenological interpretation of the energy dependence of the total cross section ${\ensuremath{\sigma}}_{T}$ and of $\frac{d\ensuremath{\sigma}}{\mathrm{dt}}$ at fixed $t$ shows, in the reaction, the contribution of a nucleon exchange process to which we must add a mechanism implying the ${\ensuremath{\Delta}}_{33}$ resonance excitation in the direct channel.

At 618 MeV bombarding energy, large fission probabilities have been observed for recoil fragments heavier than the target. The probability of sequential fission seems to depend very strongly upon angular momentum as well as upon excitation energy. The out-of-plane widths of the fission fragments together with the above observations imply that a nearly random depolarization of the heavy-fragment angular momentum may occur during the deep-inelastic processes.

Light--charged-particle emission in the reaction /sup 63/Cu + /sup 20/Ne has been studied by simultaneously measuring the atomic numbers of both deep-inelastic fragments. The results seem consistent with an evaporative process and indicate that the entrance-channel kinetic energy is essentially thermalized over a broad range of bombarding energies.