Rapidity dependence of proton cumulants and correlation functions

The dependence of multi-proton correlation functions and cumulants on the acceptance in rapidity and transverse momentum is studied. We find that the preliminary data of various cumulant ratios are consistent, within errors, with rapidity and transverse momentum independent correlation functions. However, rapidity correlations which moderately increase with rapidity separation between protons are slightly favored. We propose to further explore the rapidity dependence of multi-particle correlation functions by measuring the dependence of the integrated reduced correlation functions as a function of the size of the rapidity window.Comment: 13 pages, 5 figure

Thermal photons as a measure for the rapidity dependence of the temperature

The rapidity distribution of thermal photons produced in Pb+Pb collisions at CERN-SPS energies is calculated within scaling and three- fluid hydrodynamics. It is shown that these scenarios lead to very different rapidity spectra. A measurement of the rapidity dependence of photon radiation can give cleaner insight into the reaction dynamics than pion spectra, especially into the rapidity dependence of the temperature

Baryon Stopping in Au+Au and p+p collisions at 62 and 200 GeV

BRAHMS has measured rapidity density distributions of protons and antiprotons in both p+p and Au+Au collisions at 62 GeV and 200 GeV. From these distributions the yields of so-called "net-protons", that is the difference between the proton and antiproton yields, can be determined. The rapidity dependence of the net-proton yields from peripheral Au+Au collisions is found to have a similar behaviour to that found for the p+p results, while a quite different rapidity dependence is found for central Au+Au collisions. The net-proton distributions can be used together with model calculations to find the net-baryon yields as a function of rapidity, thus yielding information on the average rapidity loss of beam particles, the baryon transport properties of the medium, and the amount of "stopping" in these collisions.Comment: Proceedings for Quark Matter 2009, for the BRAHMS collaboratio

Overview and Recent Results from BRAHMS

The BRAHMS experiment was designed to measure and characterize in particular the properties of rapidity dependence of particle production in heavy ion collisions. The data-taking is now over, results of several years of analysis have been published and demonstrates several important features of the rapidity dependence, not envisioned from the start of the RHIC program. The bulk properties of the system formed at high rapidity resemble that of systems at lower energies at mid-rapidity when referenced via the baryo-chemical potential. New physics in AA are essentially observed at mid-rapidity including the demonstration that high-\pT suppression is a final state effect. Another key result is that in d+A collisions at forward rapidities where the very low-x region of the nucleus was probed, a strong suppression of pion production was observed consistent with the picture of gluon saturation. The latest results examines the centrality and rapidity dependence of nuclear stopping, the particle production of pions, collective expansion vs. rapidity, and the baryon enhancement at intermediate values of \pT .Comment: 8 pages, 6 figures - To appear in the conference proceedings for Quark Matter 2009, March 30 - April 4, Knoxville, Tennessee Fixed typos and minor text issues as per organizers review reques