共查询到20条相似文献,搜索用时 328 毫秒
1.
《Pramana》2003,60(5):1059-1065
We present the measurements of charged particle pseudorapidity distributions dNch/dη performed by the NA50 experiment in Pb-Pb collisions at the CERN SPS. Measurements were done at incident energies of 40
GeV (√s = 8.77 GeV) and 158 GeV (√s = 17.3 GeV) per nucleon over a broad impact parameter range. The multiplicity distributions are studied as a function of
centrality using the number of participating nucleons(N
part
), or the number of binary nucleon-nucleon collisions (Ncoll). Their values at midrapidity exhibit a linear scaling withN
part
at both energies. Particle yield increases approximately by a factor of 2 betweeny √s = 8.77 GeV and √s = 17.3 GeV. 相似文献
2.
M. V. Tokarev 《Physics of Particles and Nuclei Letters》2007,4(5):403-414
Experimental data on transverse particle spectra obtained by the STAR, PHENIX, PHOBOS, and BRAHMS collaborations at the RHIC
are analyzed in the framework of the generalized concept of z-scaling. It was developed for analysis of inclusive particle production in proton-(anti)proton collisions at high p
T
and high multiplicities. The general scheme of the approach based on the physical principles of self-similarity, locality,
and fractality is reviewed. Independence of the scaling function ψ(z) from energy, multiplicity, and atomic weight for h
±, π
±,0, K
S
0
, and Λ hadrons produced in Au-Au and Cu-Cu collisions at √s = 130 and 200 GeV is discussed. Based on z-scaling, the multiplicity dependence of pion transverse spectra up to p
T
= 25 GeV/c in Au-Au collisions at √s = 200 GeV for experiments at the RHIC is predicted.
The text was submitted by the author in English. 相似文献
3.
《Pramana》2003,60(5):921-931
The PHOBOS detector has been used to study Au + Au collisions at√sNN = 56,130, and 200 GeV Several global observables have been measured and the results are compared with theoretical models.
These observables include the charged-particle multiplicity measured as a function of beam energy, pseudo-rapidity, and centrality
of the collision. A unique feature of the PHOBOS detector is its almost complete angular coverage such that these quantities
can be studied over a pseudo-rapidity interval of |η|≤5.4. This allows for an almost complete integration of the total charged
particle yield, which is found to be about N
ch
tot
= 4200 ±470 at √sNN = 130 GeV and N
ch
tot
= 5300 ±530 at √sNN = 200 GeV.
The ratio of anti-particles to particles emitted in the mid-rapidity region has also been measured using the PHOBOS magnetic
spectrometer. Of particular interest is the ratio of anti-protons to protons in the mid-rapidity region, which was found to
be (i.e.921-1) at √sNN = 130 GeV. This high value suggests that an almost baryon-free region has been produced in the collisions. 相似文献
4.
T. J. Humanic 《Physics of Particles and Nuclei Letters》2011,8(9):903-906
A kinematic model based on the superposition of p + p collisions, relativistic geometry and final-state hadronic rescattering is used to predict two-boson HBT parameters in √s
NN
= 2.76 TeV Pb + Pb collisions. A short proper time for hadronization is assumed. Previous calculations using this model which
were performed for √s
NN
= 200 GeV Au + Au collisions were shown to describe reasonably well the trends of two-pion HBT in experiments carried out
at that energy, giving the present predictions for Pb + Pb at higher energy some degree of credibility. 相似文献
5.
The Monte Carlo version of quark-gluon string model is employed to study the multiplicity, rapidity and pr spectra of particles
in pp collisions at energies from √s = 200 GeV to 14 TeV. A good quantitative agreement with the experimental data is found in a broad energy range. It means
that the general features of ultrarelativistic pp interactions can be well understood in terms of soft- and hard-Pomeron exchanges. Predictions are made for the top LHC energy
√s = 14TeV. 相似文献
6.
P. Chung 《Physics of Particles and Nuclei Letters》2011,8(9):1019-1022
Three-dimensional source images for mid-rapidity, low transverse momentum kaon and pion pairs have been extracted from central
Au + Au collisions data at √s
NN
= 200 GeV by the STAR experiment at RHIC. The pion source function displays significant non-Gaussian features implying a
finite pion emission duration. On the other hand, the kaon source function is essentially Gaussian, consistent with instantaneous
emission from the fireball. 相似文献
7.
Hanna Paulina Zbroszczyk 《Physics of Particles and Nuclei Letters》2011,8(9):931-933
The analysis of two-particle femtoscopy provides a powerful tool to study the properties of matter created in heavy ion collisions.
Applied to identical and nonidentical hadron pairs, it makes the study of space-time evolution of the source in femtoscopic
scale possible. Baryon femtoscopy allows extraction of the radii of produced sources which can be compared to those deduced
from identical pion studies, providing additional information about source characteristics. In this paper we present the correlation
functions obtained for protons and antiprotons for Au + Au collisions √s
NN
= 62.4 and 200 GeV. On the other hand, as STAR experiment participates in Beam Energy Scan program, we present theoretical
predictions of p − p, [`(p)] - [`(p)]\bar p - \bar p and p - [`(p)]p - \bar p femtoscopic measurements, based on UrQMD simulation for √s
NN
= 5–39 GeV. 相似文献
8.
9.
M. V. Tokarev 《Physics of Atomic Nuclei》2011,74(5):799-804
The production of hadrons in heavy-ion collisions at high-p
T
provides an important information on mechanism of particle formation and constituent energy loss in medium. Such information
is needed for search of a Critical Point and signatures of phase transition. Measurements by the STAR Collaboration of charged
hadron production in Au + Au collisions at √s
NN
= 9.2 GeV over a wide transverse momentum p
T
= 0.2−4 GeV/c and at mid-rapidity range are reported. It allows for a first measurement of the spectra for charged hadrons at high p
T
at this energy. The spectra demonstrate the dependence on centrality which enhances with p
T
. The constituent energy loss and its dependence on transverse momentum of particle, and centrality of collisions are estimated
in the z-scaling approach. 相似文献
10.
J. Mercado 《Physics of Particles and Nuclei Letters》2011,8(9):885-887
ALICE is the experiment at the CERN Large Hadron Collider dedicated to study high-energy nuclear collisions which is also
carrying out a proton-proton physics program, thanks to its wide phase-space coverage and good momentum and spatial resolution.
We present first results on two-pion Bose-Einstein correlations in pp collisions at √s = 900 GeV measured with ALICE. An increase of the HBT radius with increasing event multiplicity is observed, in agreement
with previous measurements. However, a strong decrease of the radius with increasing transverse momentum, as observed at RHIC
and at Tevatron, is not evident in our analysis. 相似文献
11.
M. Zawisza 《Physics of Particles and Nuclei Letters》2011,8(9):924-927
Correlations between non-identical particles at small relative velocity probe asymmetries in the average space-time emission
points at freeze-out. The origin of such asymmetries may be from long-lived resonances, bulk collective effects, or differences
in the freeze-out scenario for the different particle species. STAR has extracted pion-proton correlation functions from a
dataset of Au+Au collisions at √s
NN
= 200 GeV. We present correlation functions in the spherical harmonic decomposition representation, for different centralities
and for different combinations of pions and (anti-)protons. 相似文献
12.
D. O. Kotov 《Physics of Atomic Nuclei》2011,74(5):794-798
Light hadrons provide a convenient tool for studying the properties of hot and dense media formed in central collisions of
relativistic heavy nuclei. The results obtained in the PHENIX experiment at the relativistic heavy-ion collider (RHIC, Brookhaven
National Laboratory, USA) by measuring nuclearmodification factors for light hadrons in various colliding systems (pp, dAu, CuCu, and AuAu) at the c.m. energies of √s
NN
= 62.4 and 200 GeV are presented. 相似文献
13.
M. C. Suarez 《Indian Journal of Physics》2011,85(7):1085-1089
We present an analysis of relative baryon to meson production for intermediate transverse momentum hadrons associated with
a high-p
T
trigger. The results of pion and (anti)proton spectra and ratios are presented for the “jet” and “ridge” components of the
two-dimensional Δν − Δϕ triggered correlations in central Au+Au collisions at ?{sNN }\sqrt {s_{NN} } = 200 GeV. We compare these results with the inclusive (non-triggered) measurements for the same data, and discuss our observations
in conjunction with the results from d+Au, and pp data. 相似文献
14.
T. J. Tarnowsky 《Indian Journal of Physics》2011,85(7):1091-1095
Long-range forward-backward multiplicity correlations have been measured in heavy ion collisions at RHIC. Results for short
and long-range multiplicity correlations (forward-backward) are presented for several systems (Au+Au, Cu+Cu, and pp) and energies (e.g.
?{sNN }\sqrt {s_{NN} } = 200 and 62.4 GeV). A strong, long-range correlation is seen for central heavy ion collisions at ?{sNN }\sqrt {s_{NN} } = 200 GeV that vanishes in semi-peripheral events and pp collisions. There is no apparent scaling with the number of participants (N
part) involved in the collision. These correlations provide information about the longitudinal behavior of the system formed in
heavy ion collisions. To access the transverse behavior, the clusters produced in the same heavy ion collisions have been
characterized by a study of the energy and system size dependence of the percolation density parameter (ρ). The relationship between the long-range correlation and percolation has been explored to characterize the hadron-quark/gluon
phase transition and rapid thermalization of the system. 相似文献
15.
Edward K. Sarkisyan-Grinbaum 《Physics of Particles and Nuclei Letters》2011,8(9):875-880
We present measurements of charged particle production in proton-proton collisions at centre-of-mass energies of √s = 0.9, 2.36 and 7 TeV recorded with the ATLAS detector at the Large Hadron Collider. Events were collected using a single-arm
minimum bias trigger, charged tracks are measured with high precision in the inner tracking system. Minimum bias analysis
uses data samples at all three energies, while diffractive events are studied using a sample of events at √s = 7 TeV. To study diffractive interactions, the events that have hits on exactly one side of the ATLAS detector were selected.
The charged particle multiplicity, pseudorapidity and transverse momentum spectra are analyzed and compared to the predictions
by various Monte Carlo models. 相似文献
16.
In the framework of the quark-gluon string model, we calculate the inclusive spectra of secondaries produced in heavy-ion
collisions at intermediate (CERN SPS) and at much higher (RHIC) energies. We demonstrate that the mechanism of secondary production
changed drastically in the energy interval √s = 20–60 GeV and that it is in agreement with qualitative estimates of Glauber-Gribov theory. The results of numerical calculations
at intermediate energies are in reasonable agreement with the data without change of the model parameters. At RHIC energies,
numerically large inelastic screening correlations should be accounted for in calculations.
The text was submitted by the authors in English. 相似文献
17.
A hadron and string cascade model, JPCIAE, together with the corresponding Monte Carlo event generator, has been employed in this paper to investigate further the charge fluctuations in Au+Au collisions at Snn = 130 GeV. The default JPCIAE calculations are in good agreement with PHENIX and STAR data. We found that the thermal predictions for the π gas, the resonance π gas and quark matter deviate, respectively, from the corresponding dynamical simulations from the JPCIAE model. The discrepancies were also found between the π charge fluctuations and the charge fluctuations of all species of hadrons. However the charge fluctuations for "π from ρ and ω decay" and for all the hadrons from resonance decay are close to each other, indicating the correlation between positively and negatively charged hadrons is not sensitive to the species of hadrons. This work shows further that it is questionable to use the charge fluctuations as a signature of QGP. 相似文献
18.
Identified π±,K
±, p and -p transverse momentum spectra at mid-rapidity in √sNN = 130 GeV Au-Au collisions were measured by the PHENIX experiment at RHIC as a function of collision centrality. Average
transverse momenta increase with the number of participating nucleonsN
part similarly for all particle species. The multiplicity densities scale faster thanN
part. TheK
± andp
±yields per participant increase faster than the π± yields. We combine the PHENIX neutral and charged pion measurement and find that in central collisions forp
T >-2 GeV/c,-p andp yields are comparable to or even exceed the pion yields. 相似文献
19.
L. M. Satarov I. N. Mishustin A. V. Merdeev H. Stöcker 《Physics of Atomic Nuclei》2007,70(10):1773-1796
A (1 + 1)-dimensional hydrodynamical model in the light-cone coordinates is used to describe central heavy-ion collisions
at ultrarelativistic bombarding energies. Deviations from Bjorken scaling are taken into account by choosing finite-size profiles
for the initial energy density. The sensitivity of fluid-dynamical evolution to the equation of state and the parameters of
initial state are investigated. Experimental constraints on the total energy of produced particles are used to reduce the
number of model parameters. Spectra of secondary particles are calculated under the assumption that the transition from the
hydrodynamical stage to the collisionless expansion of matter occurs at a certain freeze-out temperature. An important role
of resonances in the formation of observed hadronic spectra is demonstrated. The calculated rapidity distributions of pions,
kaons, and antiprotons in central Au + Au collisions at √s
NN = 200 GeV are compared with experimental data of the BRAHMS Collaboration. Parameters of the initial state are reconstructed
for different choices of the equation of state. The best fit of these data is obtained for a soft equation of state and Gaussian-like
initial profiles of the energy density, intermediate between the Landau and Bjorken limits.
The text was submitted by the authors in English. 相似文献
20.
The possibility of measuring cross sections for the production of J/ψ mesons in fixed-target experiments with the proton and ion beams of the Large Hadron Collider (LHC) at CERN (Switzerland)
is considered. At the present time, measurements of charmonium production in proton-proton collisions at an energy of 7 TeV
have begun at LHC. Previously, the production of J/ψ and ψ′ mesons was studied in the NA38, NA50, and NA60 fixed-target experiments with beams of the CERN synchrotron (SPS) and in the
PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC, Brookhaven National Laboratory, USA). A normal nuclear absorption
of J/ψ mesons in proton-nucleus collisions and an enhanced, anomalous, suppression of the production of charmonium states in central
collisions of relativistic nuclei were observed. At the present time, there are no theoretical models that could describe
the entire body of experimental data. Measurements over a broad interval of proton and ion energies are required. Measurements
of charmonium production using LHC beams with fixed targets in the energy range between the SPS and RHIC energies-a beam of
7-TeV protons (√s = 114.6 GeV) and a beam of 2.75-TeV/nucleon lead ions (√s = 71.8 GeV)-will provide an additional possibility for studying the charmonium-production mechanism. Estimates of the geometric
acceptance, luminosity, and counting rate for the production of J/ψ mesons are presented. 相似文献