27 research outputs found
Rapidity dependence of deuteron production in Au+Au collisions at = 200 GeV
We have measured the distributions of protons and deuterons produced in high
energy heavy ion Au+Au collisions at RHIC over a very wide range of transverse
and longitudinal momentum. Near mid-rapidity we have also measured the
distribution of anti-protons and anti-deuterons. We present our results in the
context of coalescence models. In particular we extract the "volume of
homogeneity" and the average phase-space density for protons and anti-protons.
Near central rapidity the coalescence parameter and the space
averaged phase-space density are very similar for both protons and
anti-protons. For protons we see little variation of either or the
space averaged phase-space density as the rapidity increases from 0 to 3.
However both these quantities depend strongly on at all rapidities. These
results are in contrast to lower energy data where the proton and anti-proton
phase-space densities are different at =0 and both and depend
strongly on rapidity.Comment: Document updated after proofs received from PR
Rapidity and centrality dependence of particle production for identified hadrons in Cu+Cu collisions at GeV
The BRAHMS collaboration has measured transverse momentum spectra of pions,
kaons, protons and antiprotons at rapidities 0 and 3 for Cu+Cu collisions at
GeV. As the collisions become more central the collective
radial flow increases while the temperature of kinetic freeze-out decreases.
The temperature is lower and the radial flow weaker at forward rapidity. Pion
and kaon yields with transverse momenta between 1.5 and 2.5 GeV/c are
suppressed for central collisions relative to scaled collisions. This
suppression, which increases as the collisions become more central is
consistent with jet quenching models and is also present with comparable
magnitude at forward rapidity. At such rapidities initial state effects may
also be present and persistence of the meson suppression to high rapidity may
reflect a combination of jet quenching and nuclear shadowing. The ratio of
protons to mesons increases as the collisions become more central and is
largest at forward rapidities.Comment: 19 pages, 11 figures and 6 table
Production of Mesons and Baryons at High Rapidity and High Pt in Proton-Proton Collisions at = 200 GeV
We present particle spectra for charged hadrons and from pp collisions at =200\bar{p}/p$ ratios associated with baryon transport
Nuclear stopping and rapidity loss in Au+Au collisions at sqrt{s_{NN}}=62.4 GeV
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 sqrt{s_{NN}}=62.4
GeV are presented. The rapidity densities, dN/dy, of protons, anti-protons and
net-protons N()p-N(pbar) 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 +-0.16 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.Comment: 5 pages, 5 figures. Submitted Phys.Lett.
Kaon and Pion Production in Central Au+Au Collisions at \sqrt{s_{NN}}=62.4 GeV
Invariant pT spectra and rapidity densities covering a large rapidity
range(-0.1 < y < 3.5) are presented for and mesons from
central Au+Au collisions at = 62.4 GeV. The mid-rapidity yields
of meson particles relative to their anti-particles are found to be close to
unity (, ) while the anti-proton to
proton ratio is . The rapidity dependence of the
ratio is consistent with a small increase towards forward
rapidities while the and ratios show a steep decrease to
0.3 for kaons and 0.022 for protons at . 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
ratio, being the driving parameter.Comment: Submitted to PLB, 6 journal pages, 7 figure
A new SPS programme
A new experiemntal program to study hadron production in hadron-nucleus and nucleus-nucleus collisions at the CERN SPS has been recently proposed by the NA49-future collaboration. The physics goals of the program are: (i) search for the critical point of strongly interacting matter and a study of the properties of the onset of deconfinemnt in nucleus-nucleus collisions, (ii) measurements of correlations, fluctuations and hadron spectra at high transverse momentum in proton-nucleus collisions needed as for better understanding of nucleus-nucleus results, (iii) measurements of hadron production in hadron-nucleus interactions needed for neutrino (T2K) and cosmic-ray (Pierre Auger Observatory and KASCADE) expriments. The physics of the nucleus-nucleus program is reviewed in this presentation
Measurements of Cross Sections and Charged Pion Spectra in Proton-Carbon Interactions at 31 GeV/c
Interaction cross sections and charged pion spectra in p+C interactions at 31
GeV/c were measured with the large acceptance NA61/SHINE spectrometer at the
CERN SPS. These data are required to improve predictions of the neutrino flux
for the T2K long baseline neutrino oscillation experiment in Japan. A set of
data collected during the first NA61/SHINE run in 2007 with an isotropic
graphite target with a thickness of 4% of a nuclear interaction length was used
for the analysis. The measured p+C inelastic and production cross sections are
257.2 +- 1.9 +- 8.9 mb and 229.3 +- 1.9 +- 9.0 mb, respectively. Inclusive
production cross sections for negatively and positively charged pions are
presented as a function of laboratory momentum in 10 intervals of the
laboratory polar angle covering the range from 0 up to 420 mrad. The spectra
are compared with predictions of several hadron production models.Comment: updated version; as published by Phys. Rev.
Search for the QCD critical point at SPS energies
Lattice QCD calculations locate the QCD critical point at energies accessible at the CERN Super Proton Synchrotron (SPS). We present average transverse momentum and multiplicity fluctuations, as well as baryon and anti-baryon transverse mass spectra which are expected to be sensitive to effects of the critical point. The future CP search strategy of the NA61/SHINE experiment at the SPS is also discussed.Lattice QCD calculations locate the QCD critical point at energies accessible at the CERN Super Proton Synchrotron (SPS). We present average transverse momentum and multiplicity fluctuations, as well as baryon and anti-baryon transverse mass spectra which are expected to be sensitive to effects of the critical point. The future CP search strategy of the NA61/SHINE experiment at the SPS is also discussed