Transverse momentum spectra of protons and anti-protons measured in the rapidity range 0<y<3.1 from 0–10% central Au+Au collisions at sNN=62.4 GeV are presented. The rapidity densities, dN/dy, of ...protons, anti-protons and net-protons (Np–Np¯) have been deduced from the spectra over a rapidity range wide enough to observe the expected maximum net-baryon density. From mid-rapidity to y=1 the net-proton yield is roughly constant (dN/dy∼10), but rises to dN/dy∼25 at 2.3<y<3.1. The mean rapidity loss is 2.01±0.14±0.12 units from beam rapidity. The measured rapidity distributions are compared to model predictions. Systematics of net-baryon distributions and rapidity loss vs. collision energy are discussed.
In this work we give an attempt to introduce a temporal scale for nuclear collisions inspired by the Hubble cosmology and check it for Au+Au collisions at energies of 200 GeV/nucleon characteristic ...to BRAHMS Collaboration. We also give some correlations with different phenomena.
Invariant p sub()Tspectra and rapidity densities covering a large rapidity range (-0.1<y<3.5) are presented for pi super(+/-) and K super(+/-) mesons from central Au + Au collisions at MathML ...equation. The mid-rapidity yields of meson particles relative to their anti-particles are found to be close to unity (pi super(-)/pi super(+)not, vert, similar1, K super(-)/K super(+)not, vert, similar0.85) while the anti-proton to proton ratio is MathML equation. The rapidity dependence of the pi super(-)/pi super(+) ratio is consistent with a small increase towards forward rapidities while the K super(-)/K super(+) and MathML equation ratios show a steep decrease to not, vert, similar0.3 for kaons and 0.022 for protons at ynot, vert, similar3. It is observed that the kaon production relative to its own anti-particle as well as to pion production in wide rapidity and energy ranges shows an apparent universal behavior consistent with the baryo-chemical potential, as deduced from the MathML equation ratio, being the driving parameter.
Heavy ion collisions at RHIC energies (Au + Au collisions at
√S
NN = 200GeV
) exhibit significant new features as compared to earlier experiments at lower energies. The reaction is characterized by a ...high degree of transparency of the collision partners leading to the formation of a baryon-poor central region. In this zone, particle production occurs mainly from the stretching of the color field. The initial energy density is well above the one considered necessary for the formation of the Quark Gluon Plasma, QGP. The production of charged particles of various masses is consistent with chemical and thermal equilibrium. Recently, a suppression of the high transverse momentum component of hadron spectra has been observed in central Au + Au collisions. This can be explained by the energy loss experienced by leading partons in a medium with a high density of unscreened color charges. In contrast, such high
p
t
jets are not suppressed in d + Au collisions suggesting that the high
p
t
suppression is not due to initial state effects in the ultrarelativistic colliding nuclei.
A new design of a detector plane of sub-millimetre thickness for an electromagnetic sampling calorimeter is presented. It is intended to be used in the luminometers LumiCal and BeamCal in future ...linear \(e^+e^-\) collider experiments. The detector planes were produced utilising novel connectivity scheme technologies. They were installed in a compact prototype of the calorimeter and tested at DESY with an electron beam of energy 1-5 GeV. The performance of a prototype of a compact LumiCal comprising eight detector planes was studied. The effective Moli`ere radius at 5 GeV was determined to be (8.1 +/- 0.1 (stat) +/- 0.3 (syst)) mm, a value well reproduced by the Monte Carlo (MC) simulation (8.4 +/- 0.1) mm. The dependence of the effective Moli`ere radius on the electron energy in the range 1-5 GeV was also studied. Good agreement was obtained between data and MC simulation.
Charged-particle pseudorapidity densities are presented for the d + Au reaction at sqrts(NN) = 200 GeV with -4.2 < or = eta < or = 4.2. The results, from the BRAHMS experiment at BNL Relativistic ...Heavy-Ion Collider, are shown for minimum-bias events and 0%-30%, 30%-60%, and 60%-80% centrality classes. Models incorporating both soft physics and hard, perturbative QCD-based scattering physics agree well with the experimental results. The data do not support predictions based on strong-coupling, semiclassical QCD. In the deuteron-fragmentation region the central 200 GeV data show behavior similar to full-overlap d+Au results at sqrts(NN) = 19.4 GeV.
We present particle spectra for charged hadrons pi(+/-), K(+/-), p, and pover from pp collisions at square roots = 200 GeV measured for the first time at forward rapidities (2.95 and 3.3). The ...kinematics of these measurements are skewed in a way that probes the small momentum fraction in one of the protons and large fractions in the other. Large proton to pion ratios are observed at values of transverse momentum that extend up to 4 GeV/c, where protons have momenta up to 35 GeV. Next-to-leading order perturbative QCD calculations describe the production of pions and kaons well at these rapidities, but fail to account for the large proton yields and small pover/p ratios.
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