G. Graebner

Hot, dense hadronic and quark matter in relativistic nuclear collisions

Abstract We discuss a possible percolation of hot, dense hadronic and quark matter in violent high-energy heavy ion collisions. The quark matter is treated in the bag model as an excited state of nuclear matter. Quark matter formation probabilities λ Q as high as 50% are found for laboratory bombarding energie of several GeV/n. The actual values of λ Q , however, depend strongly on the equation of state used for the dense, hot hadronic and quark matter. Rapidly pulsating blobs of quark matter are predicted to appear as a result of the expansive flow of quark matter against the contracting influence of confinement.

3+1 DIMENSIONAL RELATIVISTIC HYDRODYNAMIC SPACE TIME EVOLUTION OF THE REACTION O(200 GeV/n)→Pb

3+1 dimensional relativistic calculations of the time-space evolution of the reaction 16O→ Pb at 200 GeV/nucleon are presented. An energy density regime of several GeV/fm3 containing more than 100 nucleons is built up. The lift time of this high energy density region turns out to be quite short, τ~4 fm/c. Therefore a transformation of the hadronic matter into a quark gluon plasma may not be achievable with such light projectiles. It is interesting, on the other hand, that collective acceleration of the whole target to rapidities Y=2–3 is obtained in collisions with impact parameters b≤4 fm/c. This should be a unique signal for fluid dynamical behaviour at these high energies.

Irradiation symmetry of heavy ion driven inertial confinement fusion (ICF) targets

The symmetry of heavy ion driven inertial confinement fusion targets is investigated with a two-dimensional Eulerian hydrodynamic code. The importance of the beam geometry is studied. The HIBALL design in its present form seems to inhibit a spherical implosion of the target. It is shown that the beam angle in the HIBALL geometry should be about 35 degrees.

Detection of possible density isomers by means of high energy reaction products

We present a drastic effect in the cross section of high energy target fragments caused by a possible density isomer in the nuclear equation of state. The fluid dynamical model used here contains dissipative processes such as shear viscosity and heat conduction as well as a thermodynamic evaporation model at a late stage of the nuclear collision. In our calculations we consider as an example the reaction Ne+U at an impact parameterb=4 fm.

Pulsating blobs of quark matter in relativistic nuclear collisions

The formation of hot, dense quark matter in violent high energy heavy ion collisions is discussed in a relativistic hydrodynamical model. Rapidly pulsating blobs of quark matter (treated in the bag model) are predicted to appear as a result of the expansive flow of the compressed quark matter against the contracting influence of confinement. The radial oscillations may result in pulsed matter emission.

Dynamics of Medium Energy Nuclear Collisions

Recent theoretical attempts to study high energy heavy ion reactions are reviewed. Special emphasis is given to the description of the dynamical evolution and to the production of pions and light fragments in the collision. Evidence for a collective quasi-hydrodynamic flow behaviour of compressed nuclear matter is presented. We show that the pion yield is sensitive to the nuclear equation of state and to the viscosity in hot dense nuclear matter. A 4? exclusive flow analysis of intermediate energy nuclear collisions can be used to reveal the compressibility coefficient of nuclear matter.

Rapidity distributions and energy densities from hydrodynamical studies at 5–200 GeV/n

3 + 1 dimensional relativistic calculations of the space-time evolution of heavy ion collisions at bombarding energies from 5 to 200 GeV/n are presented. Collisions with heavier projectiles seem to be more rewarding to form extended regimes of highly excited nuclear matter containing enough baryons for a sufficient time span to enable a transition of the hadron matter into a quark gluon plasma. A strong impact parameter dependence has to be taken into account when comparing the final baryon rapidity distributions with experimental results. Experimental results of the reactions 16O(60, 200 GeV/n)→Pb are compared with hydrodynamical calculations.