Phase transitions (SPhN)

Alice in LHC

Heavy ion collisions provide the means of forming in the laboratory samples of nuclear matter under extreme conditions of density and pressure. It is thus possible to study two particular regimes of the equation of state of nuclear matter, the liquidgas phase transition and the quark-gluon plasma, which are predicted by realistic nuclear models and strong interaction theory, respectively. The liquid-gas phase transition is actively investigated experimentally by the INDRA collaboration at GANIL and GSI. This programme is currently in a data interpretation phase to which the service actively contributes.

SPhN also participates in the search for and the study of the quark-gluon plasma (QGP). A signature of this plasma is colour screening, which is expressed as a suppression of heavy resonances (J/Ψ and Y) consisting of quark-antiquark pairs. It is this channel that the service has chosen in studying the production of these resonances through their decay into pairs of muons in the PHENIX experiment at RHIC (BNL) and the ALICE experiment at the LHC (CERN). We have participated in data taking at PHENIX and in the analysis for the past three years. The ALICE experiment is in the course of preparation. Our main effort is in the construction of the muon spectrometer, a key element of this experiment. It will enable the QGP to be studied in detail from about 2008 onwards at the LHC, which will offer an available energy 30 times larger than that of RHIC.

#574 - Last update : 02/10 2005

Nuclear Physics Division

Institute of Research into the Fundamental Laws of the Universe