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Conference: Bucharest University Faculty of Physics 2002 Meeting

Section: Nuclear and Elementary Particles Physics

Title:

Charged particle multiplicity distributions in Au-Au collisions at RHIC-BNL energies (BRAHMS Experiment)

Authors:

D. Argintaru[2], I.G. Bearden[6], D. Beavis[1], C. Besliu[2], Y. Blyakhman[5], H. Boggild[6], J. Brzychczyk[3], B. Budick[5], C. Chasman[1], C.H. Christensen[6], P. Christiansen[6], J. Cibor[7], F. Constantin[2], R. Debbe[1], D. Felea[2], J.J. Gaardhoje[6], K. Grotowski[3], K. Hagel[7], O. Hansen[6], A. Holm[6], A.K. Holme[11], H. Ito[9], E. Jacobsen[6], Al. Jipa[2], J.I. Jorde[8], F. Jundt[12], C.E. Jorgensen[6], E.J. Kim[4], T. Kozik[3], T. Keutgen[3], T.M. Larsen[11], J.H. Lee[1], Y.K. Lee[4], G. Lovhoiden[11], Z. Majka[3], A. Makeev[7], E. McBreen[1], M. Murray[7], J. Natowitz[7], B.S. Nielsen[6], K. Olchanski[1], J.W. Olness[1], D. Ouerdane[6], R. Planeta[3], F. Rami[12], C. Ristea[2], O. Ristea[2], D. Roehrich[8], B. Samset[11], S.J. Sanders[9], R. Scheetz[1], Z. Sosin[3], P. Staszel[3], T.F. Thorstein[8], T.S. Tveter[11], F. Videbaek[1], R. Wada[7], A. Wieloch[3], R. Zaharia[2], I.S. Zgura[2], Ionut Arsene[2], Ciprian Mitu[2], Mihai Potlog[2], Emil Stan[2]

Affiliation:

BRAHMS Collaboration, Atomic and Nuclear Physics Department, Faculty of Physics, University of Bucharest, ROMANIA

[1] Brookhaven National Laboratory, Upton, NY 11973, U.S.A.

[2] University of Bucharest, ROMANIA

[3] Jagellonian University, Krakow, POLAND

[4] Johns Hopkins University, Baltimore, MD 21218, U.S.A.

[5] New York University, New York, NY 10003, U.S.A.

[6] Niels Bohr Institute for Astronomy, Physics and Geophysics, University of Copenhagen, DENMARK

[7] Texas A&M University, College Station, TX 77843-3366, U.S.A.

[8] Fysisk Institutt, Universitetet i Bergen, Bergen, NORWAY

[9] University of Kansas, Lawrence, KS 66045, U.S.A.

[10] University of Lund, 22100 Lund, SWEDEN

[11] University of Oslo, Oslo, NORWAY

[12] University Louis Pasteur, Strasbourg, FRANCE

E-mail

Keywords:

Abstract:

The BRAHMS Experiment (Broad RAnge Hadronic Magnetic Spectrometers) takes place at the Relativistic Heavy Ion Collider (RHIC) from Brookhaven National Laboratory and is searching for a transition of matter into a new phase called quark-gluon plasma (QGP), phase transition that appears in extreme conditions of nuclear matter densities and temperatures. Important signals for this transition are related to dependencies of the charged particle multiplicity distributions on the pseudorapidity range. The charged particle multiplicity distributions in Au-Au collisions at RHIC energies are obtained from the global detectors measurements. These detectors are : # An array of Si strip detectors and scintillation tiles placed around the interaction region; they cover the range |eta|<2 in pseudorapidity, measuring the majority of charged particles. # Two systems of Cerenkov detectors (Beam-Beam Counters) placed both sides of the nominal interaction point at 220 cm and cover the range 3<|eta|<4.3 in pseudorapidity. These detectors are used for vertex determination and supply a level zero trigger for the entire experiment. # Zero Degree Calorimeters placed at zero degree respect to the beam axis, both sides of the vertex, measuring the spectator neutrons from the nuclear reactions. These detectors supplies information about the reaction centrality and could estimate the interaction vertex. The paper present some results on charged particle multiplicities in different pseudorapidity ranges, at different impact parameters. Interesting dependencies of the average charged particle multiplicities on the pseudorapidity range, impact parameters and total available energy in the centre of mass system. Some comparisons with the simulation codes predictions and theoretical model estimations are included, too.