Physics of high-energy heavy-ion collisions

Abstract

This is a review of the present status of heavy-ion collisions at intermediate energies. The main goal of heavy-ion physics in this energy regime is to shed some light on the nuclear equation of state (EO?.), hence we present the basic concept of the EOS in nuclear matter as well as of nuclear shock waves which provide the key mechanism for the compression of nuclear matter.The main part of this article is devoted to the models currently used for describing heavy-ion reactions theoretically and to the observables useful for extracting information about the EOS from experiments. A detailed discussion of the flow effects with a broad comparison with the available data is presented.The many-body aspects of such reactions are investigated via the multifragmentation break up of excited nuclear systems and a comparison of model calculations with the most recent multifragmentation experiments is presented.

Directed flow of light nuclei in Au+Au collisions at 10.8AGeV/c

“…Initially, the theoretical prediction of the effect was based on the observation that the collective motion of the higher mass fragments should be less sensitive to thermal distortions. Later, calculations [4][5][6] showed the same effect in models based on a picture where the production of light nuclei takes place by the coalescence of nucleons close to each other in momentum and configuration space. Experimental data [11] for particles with transverse momentum greater than 0.2 GeV/c per fragment nucleon were found to be consistent with momentum space coalescence, but a complete understanding of the effect is still lacking.…”

“…At lower beam energies (kinetic energies from about 0.2 to 1.15 GeV per nucleon) flow of light fragments has been studied intensively both experimentally [7][8][9][10][11][12][13][14] and theoretically [3][4][5][6]15] (and references therein).…”

Stability and instability of a hot and dilute nuclear droplet

“…Increasing interest [1,2,3,4] in this multifragmentation reaction has been initiated by the observation [5] that the fragment-mass distribution is proportional to A −σ (power law with σ ≈ 2.6) indicating that the process may be related to the critical point of the liquid-gas phase transition of nuclear matter. Indeed, simulations within molecular dynamics [6,7,8] and mean-field approaches [9,10,11,12] show that initial compression in central heavy-ion collisions or pure excitation of a nucleus by abrasion of nucleons or by absorption of light ions, pions or antiprotons cause the system to expand and to break up into pieces in a low-density regime. Powerlaw fragment-mass distributions have also been obtained from dynamical nucleation in a thermodynamically unstable nucleonic system [13].…”

Composition of Nuclear Matter with Light Clusters and Bose–Einstein Condensation of $$\alpha $$ α Particles

“…The topics of current interest are, for example, the improvements on the supernova and warm neutron star equations of state and thermodynamics [7,8] which include the multi-cluster composition of matter [9,10,11,12,13,14,15,16,17,18,19,20,21]. Another aspect of the problem is the effects of light clusters in intermediate energy heavy ion collisions [22,23,24,25,26,27] which were extensively studied using various methods, see for example [28,29,30]. Furthermore, the general many-body problem of bound state formation in nuclear medium is an outstanding problem on its own right [31,32,33,34,35,36,37,38,39,40,41,42].…”