Nuclei in their ground states behave as quantum fluids, Fermi liquids. When the density, or the temperature of that fluid increases, various phase transitions may occur. Thus, for moderate excitation energies, of the order of a few MeV per nucleon, nuclear matter behaves as an ordinary fluid with gaseous and liquid phases, and a coexistence region below a critical temperature. For higher excitation energies, of the order of a few Ge V per nucleon, the composition of nuclear matter changes, nucleons being gradually turned into baryonic resonances of various kinds. Finally, when 3 the energy density exceeds some few GeV /fm , nuclear matter turns into a gas of weakly interacting quarks and gluons. This new phase of matter has been called the quark-gluon plasma, and its existence is a prediction of Quantum Chromodynamics. Collisions of heavy ions produce nuclear matter with various degrees of excitation. In fact, by selecting the impact parameter and the bombarding energy, one can produce nuclear matter with specified baryonic density and excitation energy. Several major experimental programs are under way (for instance at GANIL, with the detector INDRA, at GSI with the detector ALADIN, at the CERN-SPS, at the AGS of Brookhaven, etc. ), or are in preparation (RRIC, LHC, etc. ). The goal of these experiments is to get evidence for the different phases of nuclear matter predicted by the theory, and to study their properties.

Inhalt
Section I Thermal and chemical equilibrium.- Probing thermalizing nuclear matter with hard photons.- Hadron multiplicities in high energy e+e?, p?p and pp collisions with a statistical - thermal model.- Phase transitions without thermodynamic limit.- The role of statistics and thermodynamics in nuclear multifragmentation.- Hydrodynamic description of very high energy heavy ion collisions.- Section II Non-equilibrium dynamics.- Hadronic transport model with a phase transition.- Baryon transport dynamics : from p p to Pb Pb collisions.- Semihard interactions in nuclear collisions based on a unified approach to high energy scattering.- Dynamics of the chiral phase transition.- Filamentation instability in ultrarelativistic heavy-ion collisions.- Section III Phase transitions and the critical behaviour.- Critical behaviour in finite temperature QCD.- Chaos as a signature of quark hadron phase transition.- Universality of the off-equilibrium critical fragmentation.- Bose-Einstein condensation in trapped atomic gases.- Thermodynamics and cluster content of finite excited systems of classical particles with short and long range interactions.- Percolation approach to the liquid gas phase transition Isospin degree of freedom.- Critical phenomena in finite systems.- Deuteron versus ?-particle condensation and precritical pair fluctuations in low density nuclear matter.- Section IV Hadronic matter and the quark gluon plasma.- QCD phases at high density and instantons.- Colour deconfinement in high energy collisions.- The phase transition between the quark-gluon plasma and the hadronic matter : What can we learn from vector mesons?.- Quark gluon plasma in A + A collisions at CERN SPS.- Chemical equilibrium in ultra-relativistic nuclear collisions.- Flowphenomena as possible signals of the QCD phase transition.- Quark-hadron interactions in nuclear matter : Deconfinement signal.- Constraining a simple hadronization model of relativistic heavy-ion collisions using hadronic observables.- Probing chiral symmetry restoration with heavy ions.- Low mass dilepton production at the CERN SPS.- Strangeness and in-medium effects in heavy-ion collisions at SIS energies.- Bose-Einstein condensation in multipion systems.- Determination of emission times using two particle correlation.- Section V Multifragmentation, liquid gas phase transition.- Boltzmann Langevin approaches.- Liquid-gas phase transition in finite nuclei within fermionic molecular dynamics.- Multifragmentation a dynamical or a statistical process?.- Multifragmentation in heavy ion reactions : Dynamical effects and thermalization.- The caloric curve of hot nuclei.- Critical behavior in nuclear multifragmentation : A determination of critical exponents and the scaling function.- Light particle probes of the dynamical evolution of multifragmentation reactions.- Cluster-cluster collisions : Fusion, phase transition and fragmentation phenomena.- On microscopic insights into metal cluster fragmentation.- List of participants.