Antiparticle to particle ratios and identified hadron spectra in Cu+Cu and Au+Au collisions

New results on antiparticle to particle ratios in Cu+Cu and Au+Au collisions at sqrt(s_NN) = 62.4 and 200 GeV from the PHOBOS experiment at RHIC are presented. Transverse momentum spectra of pions, kaons, protons and antiprotons from Au+Au collisions at sqrt(s_NN) = 62.4 GeV close to mid-rapidity are also discussed. Antiparticle to particle ratios are found to be remarkably independent of the collision centrality in both colliding systems. The collision energy dependence of the pbar/p ratios is very significant in Cu+Cu collisions. Baryons are found to have substantially harder transverse momentum spectra than mesons. The pT region in which the proton to pion ratio reaches unity in central Au+Au collisions at sqrt(s_NN) = 62.4 GeV fits into a smooth trend as a function of collision energy. The observed particle yields at very low pT are comparable to extrapolations from higher pT for kaons, protons and antiprotons. The net proton yield at mid-rapidity is found to be proportional to the number of participant nucleons in Au+Au collisions at 62.4 and 200 GeV energies.Comment: 5 pages, 3 figures, Presented at the Quark Matter 2006 conference in Shanghai, Chin

BRAHMS Overview

A brief review of BRAHMS measurements of bulk particle production in RHIC Au+Au collisions at $\sqrt{s_{NN}}=200GeV$ is presented, together with some discussion of baryon number transport. Intermediate $p_{T}$ measurements in different collision systems (Au+Au, d+Au and p+p) are also discussed in the context of jet quenching and saturation of the gluon density in Au ions at RHIC energies. This report also includes preliminary results for identified particles at forward rapidities in d+Au and Au+Au collisions.Comment: 8 pages 6 figures, Invited plenary talk at 5th International Conference on Physics and Astrophysics of Quark Gluon Plasma (ICPAQGP 2005), Salt Lake City, Kolkata, India, 8-12 Feb 200