Pseudorapidity Distributions Of Charged Particles Research Articles

VALIDITY OF NAKAMURA–KUDO SCALING OF CHARGED PARTICLE PSEUDORAPIDITY DISTRIBUTION IN RELATIVISTIC HIGH-ENERGY h–A INTERACTIONS

Nakamura and Kudo proposed a scaling form for charged particle pseudorapidity distributions on the basis of scaling in the mean hypothesis. This scaling form was tested primarily for hadron–hadron interaction data. But no attempt was made to verify this for hadron–nucleus interaction which offers unique opportunity to learn about the space–time structure of a strongly interacting process. In view of this we report an analysis of p–AgBr interaction data at 400 GeV/c and 200 GeV/c, π-–AgBr interaction data at 200 GeV/c and 350 GeV/c to test its (Nakamura–Kudo scaling) validity in hadron–nucleus interaction. In all cases the data show a remarkable agreement with the scaling behavior of Nakamura and Kudo.

Centrality dependences of the pseudorapidity distributions of charged particles in Au+Au collisions at RHIC energies

By employing the Glauber model, we give the centrality dependences of the numbers of participants and binary nucleon-nucleon collisions in nucleus-nucleus collisions. By taking into account the energy loss of the participants in their multiple collisions, we then present the pseudorapidity distributions of charged particles in nucleus-nucleus collisions as a function of beam energy and impact parameter. Finally, we analyze the centrality dependence of the pseudorapidity of the charged particles in Au+Au collisions at energies from = 19.6 to 200 GeV. The theoretical results are in good agreement with the experimental observations of the RHIC-PHOBOS collaboration.

Pseudorapidity Distributions of Charged Particles and Contributions of Leading Nucleons in Cu-Cu Collisions at High Energies

The pseudorapidity distributions of charged particles produced in Cu-Cu collisions over an energy range from 22.4 GeV to 200 GeV are investigated by using a multi-source ideal gas model which contains systematically the contributions of leading nucleons. It is shown that the calculated results are in agreement with the experimental data and the model is successful in the description of the pseudorapidity distribution of charged particles. The contributions of leading nucleons increase with the increasing impact parameter. The cylinder length (the longitudinal shift of the interacting system) in rapidity space increases with the increasing energy and does not depend on centrality at a given energy.

Extrapolation of multiplicity distribution in collisions to LHC energies

The multiplicity (Nch) and pseudorapidity distribution (dNch/dη) of primary charged particles in p + p collisions at Large Hadron Collider (LHC) energies of 10 and 14 TeV are obtained from extrapolation of existing measurements at lower . These distributions are then compared to calculations from PYTHIA and PHOJET models. The existing measurements are unable to distinguish between a logarithmic and power law dependence of the average charged particle multiplicity (⟨Nch⟩) on , and their extrapolation to energies accessible at LHC give very different values. Assuming a reasonably good description of inclusive charged particle multiplicity distributions by negative binomial distribution (NBD) at lower to hold for LHC energies, we observe that the logarithmic dependences of ⟨Nch⟩ are favored by the models at midrapidity. The dNch/dη versus η distributions for the existing measurements are found to be reasonably well described by a function with three parameters which accounts for the basic features of the distribution, height at midrapidity, central rapidity plateau and the higher rapidity fall-off. Extrapolation of these parameters as a function of is used to predict the pseudorapidity distributions of charged particles at LHC energies. dNch/dη calculations from PYTHIA and PHOJET models are found to be lower compared to those obtained from the extrapolated dNch/dη versus η distributions for a broad η range.

System Size, Energy, and Centrality Dependence of Pseudorapidity Distributions of Charged Particles in Relativistic Heavy-Ion Collisions

We present the first measurements of the pseudorapidity distribution of primary charged particles in Cu+Cu collisions as a function of collision centrality and energy, sqrt[s_{NN}]=22.4, 62.4, and 200 GeV, over a wide range of pseudorapidity, using the PHOBOS detector. A comparison of Cu+Cu and Au+Au results shows that the total number of produced charged particles and the rough shape (height and width) of the pseudorapidity distributions are determined by the number of nucleon participants. More detailed studies reveal that a more precise matching of the shape of the Cu+Cu and Au+Au pseudorapidity distributions over the full range of pseudorapidity occurs for the same N{part}/2A rather than the same N_{part}. In other words, it is the collision geometry rather than just the number of nucleon participants that drives the detailed shape of the pseudorapidity distribution and its centrality dependence at RHIC energies.

Charged-particle (pseudo-)rapidity distributions inp+p¯/p+pandPb+Pb/Au+Aucollisions from UrQMD calculations at energies available at the CERN Super Proton Synchrotron to the Large Hadron Collider

We present results for final state charged-particle (pseudo-)rapidity distributions in $p+\overline{p}/p+p$ and $\mathrm{Pb}+\mathrm{Pb}/\mathrm{Au}+\mathrm{Au}$ at ultra high energies ($17.3 \mathrm{GeV}\ensuremath{\leqslant}\sqrt{{s}_{\mathit{NN}}}\ensuremath{\leqslant}14 \mathrm{TeV}$) from the Ultra-relativistic Quantum Molecular Dynamics (UrQMD-v2.3) model. In addition, excitation functions of produced charged-particle multiplicities (${N}_{\mathrm{ch}}$) and pseudorapidity spectra are investigated up to CERN Large Hadron Collider energies. Good agreement is observed between UrQMD and measured pseudorapidity distributions of charged particles up to the highest Tevatron and $\mathrm{Sp}\overline{\mathrm{p}}\mathrm{S}$ energies.

Charged-particle pseudorapidity distributions in Au+Au collisions at RHIC

Using the Glauber model, we present the formulas for calculating the numbers of participants, spectators and binary nucleon-nucleon collisions. Based on this work, we get the pseudorapidity distributions of charged particles as the function of the impact parameter in nucleus-nucleus collisions. The theoretical results agree well with the experimental observations made by the BRAHMS Collaboration in Au + Au collisions at GeV in different centrality bins over the whole pseudorapidity range.

CENTRALITY, SYSTEM SIZE AND ENERGY DEPENDENCE OF CHARGED PARTICLE PSEUDORAPIDITY DISTRIBUTION

Utilizing the three-fireball picture within the quark combination model, we study systematically the charged particle pseudorapidity distributions in both Au + Au and Cu + Cu collision systems as a function of collision centrality and energy, [Formula: see text], 62.4, 130 and 200 GeV, in the full pseudorapidity range. We find that: (i) the contribution from leading particles to dN ch /dη distributions increases with the decrease of the collision centrality and energy respectively; (ii) the number of leading particles is almost independent of the collision energy, but it does depend on the nucleon participants N part ; (iii) if Cu + Cu and Au + Au collisions at the same collision energy are selected to have the same N part , the resulting charged particle dN/dη distributions are nearly identical, in both the midrapidity particle density and the width of the distribution; this is true for both 62.4 GeV and 200 GeV data; (iv) the limiting fragmentation phenomenon is reproduced. We predict the total multiplicity and pseudorapidity distribution for the charged particles in Pb + Pb collisions at [Formula: see text]. Finally, we give a qualitative analysis of N ch /〈N part /2〉 and dN ch /dη/〈N part /2〉|η≈0 as a function of [Formula: see text] and N part from the RHIC to the LHC.

Dependence of charged particle pseudorapidity distributions on centrality and energy inp(d)Acollisions at high energies

The pseudorapidity distributions of charged particles produced in deuteron-gold ($d$-Au) and proton-emulsion ($p$-Em) collisions at high energies are studied in the framework of the two-cylinder model. The experimental results of nuclear reactions induced by protons and deuterons [$p(d)A$ collisions] can be simply described by this model. The dependencies of parameter values on centrality for $d$-Au collisions and on nucleon-nucleon center-of-mass energy for $p$-Em collisions are obtained. The formula obtained by this model is a unified formula in the description of (pseudo)rapidity distributions of final-state particles produced in different interactions over an energy range from intermediate accelerator energy to ultrahigh cosmic-ray energy.

Widths of charged particle pseudorapidity density distributions in high energy [formula omitted] and AA collisions

The paper presents a fit to pseudorapidity distributions of final-state charged particles produced in hadron and heavy ion experiments at different center-of-mass energies. Distributions of charged particles measured in p p ¯ , p ( d ) A , and AA collisions at high energies are presented and good agreement between the fit and the data is found. The basis of the fits is a semi-empirical formula which is obtained from a simple Feynman gas model, namely the two-cylinder gas model. For p p ¯ and AA collisions, the dependence of the width of charged particle pseudorapidity density distributions on logarithmic center-of-mass energy is studied and found to be a linear relationship. Meanwhile, the dependences of the two-cylinder length, single cylinder length, and gap width between the two cylinders on logarithmic center-of-mass energy are found to be linear relationships. As another check and application of the semi-empirical formula, the rapidity distributions of net-protons emitted in AA collisions at high energies are studied. Similar conclusions are obtained.

Local Thermalization in d+Au Collisions

The extent of a locally equilibrated parton plasma in d + Au collisions at sqrt(s_NN) = 200 GeV is investigated as a function of centrality in a nonequilibrium-statistical framework. Based on a three-sources model, analytical solutions of a relativistic diffusion equation are in precise agreement with recent data for charged-particle pseudorapidity distributions. The moving midrapidity source indicates the size of the local thermal equilibrium region after hadronization. In central d + Au collisions it contains 19% of the produced particles.

Particle production in nuclear collisions over a broad centrality range from the PHOBOS experiment

The PHOBOS collaboration has studied the pseudorapidity and transverse momentum distributions of charged particles produced in heavy ion collisions. Results from Au+Au collisions at various center-of-mass energies and over a broad range of centrality are presented here. The data are compared to Cu+Cu, p+p and d+Au collisions at corresponding energies and centralities. The data are found to exhibit simple scaling properties such as the observed factorization of collision energy and geometry dependences. The presented data help us distinguish between models of particle production in relativistic heavy ion collisions.

Multiplicity and pseudorapidity distributions of charged particles and photons at forward pseudorapidity in Au+Au collisons atsNN=62.4GeV

We present the centrality dependent measurement of multiplicity and pseudorapidity distributions of charged particles and photons in Au + Au collisions at sqrt{s_NN} = 62.4 GeV. The charged particles and photons are measured in the pseudorapidity region 2.9 < eta < 3.9 and 2.3 < eta < 3.7, respectively. We have studied the scaling of particle production with the number of participating nucleons and the number of binary collisions. The photon and charged particle production in the measured pseudorapidity range has been shown to be consistent with energy independent limiting fragmentation behavior. The photons are observed to follow a centrality independent limiting fragmentation behavior while for the charged particles it is centrality dependent. We have carried out a comparative study of the pseudorapidity distributions of positively charged hadrons, negatively charged hadrons, photons, pions, net protons in nucleus--nucleus collisions and pseudorapidity distributions from p+p collisions. From these comparisons we conclude that baryons in the inclusive charged particle distribution are responsible for the observed centrality dependence of limiting fragmentation. The mesons are found to follow an energy independent behavior of limiting fragmentation while the behavior of baryons seems to be energy dependent.

Local thermalization in the [formula omitted] system

The extent of a locally equilibrated parton plasma in d+Au collisions at sNN=200 GeV is investigated as a function of collision centrality in a nonequilibrium-statistical framework. Based on a three-sources model, analytical solutions of a relativistic diffusion equation are in precise agreement with recent data for charged-particle pseudorapidity distributions. The moving midrapidity source indicates the size of the local thermal equilibrium region after hadronization. In central d+Au collisions it contains about 19% of the produced particles, and its relative importance rises with decreasing centrality.

Scaling of charged particle production ind+Aucollisions atsNN=200GeV

The measured pseudorapidity distributions of primary charged particles over a wide pseudorapidity range of |{eta}|{ N{sub ch}{sup pp}, and the energy dependence of the density of charged particles produced in the fragmentation region exhibits extended longitudinal scaling.

PSEUDORAPIDITY DISTRIBUTION OF CHARGED PARTICLES IN $p\bar p$ AND AA COLLISIONS AT HIGH ENERGIES

The pseudorapidity distributions of charged particles produced in [Formula: see text] annihilations and AA collisions at high energies are investigated by using a revised thermalized cylinder model. The Monte Carlo calculated results are compared and found to be in good agreement with the experimental data of [Formula: see text] annihilations at center-of-mass energy [Formula: see text], 546, 200, and 53 GeV, Au–Au collisions at [Formula: see text] and 130 A GeV, and Pb–Pb collisions at [Formula: see text].

Pseudorapidity distribution of charged particles in d+Au collisions at sqrt[sNN]=200 GeV.

The measured pseudorapidity distribution of primary charged particles in minimum-bias d+Au collisions at sqrt[s(NN)]=200 GeV is presented for the first time. This distribution falls off less rapidly in the gold direction as compared to the deuteron direction. The average value of the charged particle pseudorapidity density at midrapidity is <dN(ch)/d eta>|eta|< or =0.6)=9.4+/-0.7(syst) and the integrated primary charged particle multiplicity in the measured region is 82+/-6(syst). Estimates of the total charged particle production, based on extrapolations outside the measured pseudorapidity region, are also presented. The pseudorapidity distribution, normalized to the number of participants in d+Au collisions, is compared to those of Au+Au and p+(-)p systems at the same energy. The d+Au distribution is also compared to the predictions of the parton saturation model, as well as microscopic models.

Pseudorapidity distributions of charged particles in d + Au and p + p collisions at

The measured pseudorapidity distributions of primary charged particles are presented for d+Au and p+p collisions at over a wide pseudorapidity range of |η|⩽ 5.4. The results for d+Au collisions are presented for minimum-bias events and as a function of collision centrality. The measurements for p+p collisions are shown for minimum-bias events. The ratio of the charged particle multiplicity in d+Au and p+A collisions relative to that for inelastic p+p collisions is found to depend only on ⟨Npart⟩, and it is remarkably independent of collision energy and system mass. The deuteron and gold fragmentation regions in d+Au collisions are in good agreement with proton nucleus data at lower energies.

Indication of quark deconfinement and evidence for a Hubble flow in 130 and 200 GeV Au+Au collisions

Buda–Lund hydro-model fits are compared to BRAHMS, PHENIX, PHOBOS and STAR data on identified particle spectra, two-particle Bose–Einstein or HBT correlations, charged particle pseudorapidity distributions and pseudorapidity as well as pT dependent elliptic flow in and 200 GeV Au+Au collisions at RHIC. Preliminary results indicate that 7/8 of the particle emitting volume is rather cold, with surface temperature of 105 MeV, but the temperature has a distribution and the most central 1/8 of the volume is superheated to temperatures above the critical value, T(x) > Tc = 172 ± 3 MeV.

Charged particle production ind+Aucollisions atsNN=200GeV

We have given an explanation for the pseudorapidity distribution of charged particles produced in d+Au collisions at sNN=200GeV [the maximum relativistic heavy ion collider (RHIC) energy]. A simple cylinder model is used in this paper which contains four components: leading projectile protons, leading target protons, cascade collisions in the gold spectator, and a cylinder. The model gives a good description for the experimental data obtained with the PHOBOS detector at RHIC. The high stage and high peak in the gold fragmentation region of the pseudorapidity distribution are contributed by the leading gold protons and the cascade collisions in the gold spectator, respectively.