Multiplicity distributions of produced particles in proton-nucleus collisions at 200 GeV

We analyse data for multiplicity distributions of negative particles which are produced inpp, pAr andpXe collisions, at 200 GeV. We compare two hypotheses with the data: universal (KNO) scaling and the model of independent sources. The data favour the second model.     

Multiplicity distributions in rapidity intervals forp-p andp-nucleus interactions at 200 GeV

Multiplicity distributions of charged particles produced in proton-proton, proton-argon and proton-xenon inelastic collisions at 200 GeV/c in various rapidity intervals are presented. Nuclear target data are analysed separately for the forward and the backward hemispheres. Results of a similar analysis for only negative particles are shown. The data are well parametrized in terms of negative binomial distributions. However, such a parametrization fails in describing thep-nucleus multiplicity distributions of charged particles for large rapidity intervals comprising both hemispheres. Parameters characteristic for the clan model of Giovannini and Van Hove are also presented.     

Multiplicity of charged particles in 800 GeV p-p interactions

Results are reported concerning the charged-particle multiplicity distribution obtained in an exposure of the high-resolution hydrogen bubble chamber LEBC to a beam of 800 GeV protons at the Fermilab MPS. This is the first time that such data have been available at this energy. The distribution of the number n_ch of charged particles produced in inelastic interactions obeys KNO-scaling. The average multiplicity is 〈n_ch〉 = 10.26±0.15. For n_ch⩾8 the data can be well fitted to a negative binomial. The difference between the overall experimental multiplicity distribution and that resulting from the latter fit is in agreement with the contribution expected from diffractive processes.     

Multiplicity distributions in proton-nucleus collisions at 67 and 200 GeV

New data, concerning multiplicities in collisions of 67 and 200 GeV protons in emulsions are presented. Various parameters of multiplicity distributions in collisions of protons with nuclei of photographic emulsion at primary energies between a few and about 1000 GeV are compared with p-p collisions.     

Multiplicity and angular distributions of charged particles in interactions of Fe in emulsion at 2.5A GeV/c

Data are presented on multiplicity and angular distributions of charged secondary particles from inelastic interactions of ⁵⁶Fe in emulsion at 2.5A GeV/c. Comparisons with data, at nearby the same incident momentum per nucleon from p-A, ¹⁴N-A, ¹⁶O-A and ⁴⁰Ar-A collisions are performed in order to trace the dependence on projectile and target mass. Furthermore, the ⁵⁶Fe data are compared with the results from a cascade-evaporation model. This comparison shows some significant deviations between the model and the data which are not observed for light ion induced collisions.     

Multiplicity distributions of charged hadrons invp and charged current interactions

Using data onvp and charged current interactions from a bubble chamber experiment with BEBC at CERN, the multiplicity distributions of charged hadrons are investigated. The analysis is based on 20000 events with incidentv and 10000 events with incident . The invariant massW of the total hadronic system ranges from 3 GeV to 14 GeV. The experimental multiplicity distributions are fitted by the binomial function (for different intervals ofW and in different intervals of the rapidityy), by the Levy function and the lognormal function. All three parametrizations give acceptable values forX ². For fixedW, forward and backward multiplicities are found to be uncorrelated. The normalized moments of the charged multiplicity distributions are measured as a function ofW. They show a violation of KNO scaling.     

Centrality dependence of pseudorapidity distributions of baryons in heavy ion collisions at RHIC

The energy and centrality independence of the limiting fragmentation for produced mesons have been used to extract the reduced pseudorapidity (η′ = η − η _beam ) distributions of charged baryons at forward rapidity. The distribution crosses at η′ ≈ = −1 suggesting the prominence of beam protons above that rapidity. The loss of beam rapidity has been extracted which has been found to increase with centrality.     

Centrality dependence of charged-particle pseudorapidity distributions from d + Au collisions at sqrt[sNN] = 200 GeV

Charged-particle pseudorapidity densities are presented for the d + Au reaction at sqrt[s(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 sqrt[s(NN)] = 19.4 GeV.     

Multiplicity and pseudorapidity distributions of photons in Au+Au collisions at square root of (S(NN)) = 62.4 GeV

We present the first measurement of pseudorapidity distribution of photons in the region 2.3 < or = eta < or = 3.7 for different centralities in Au+Au collisions at square root of (S(NN)) = 62.4 GeV. We find that the photon yield scales with the number of participating nucleons at all collision centralities studied. The pseudorapidity distribution of photons, dominated by pi0 decays, has been compared to those of charged pions, photons, and inclusive charged particles from heavy-ion and nucleon-nucleon collisions at various energies. The photon production has been shown to be consistent with the energy and centrality independent limiting fragmentation scenario.     

The transverse-energy distributions of 32S-nucleus collisions at 200 GeV per nucleon

Transverse-energy distributions have been measured for the collisions of the ³²S nucleus with Al, Ag, W, Pt, Pb, and U target nuclei, at an incident energy of 200 GeV per nucleon. The shapes of these distribution reflect the geometry of the collisions, including the deformation effects. For central collisions, the transverse-energy production in the region −0.1<η_lab<2.9 increases approximately as A^0.5, where A is the atomic mass number of the target. This increase is accompanied by a relative depletion in the forward region η_lab > 2.9. These results are compared with those obtained under similar conditions with incident ¹⁶O nuclei. A comparison is also made with the predictions of a Monte Carlo generator based on the dual parton model. Finally, we give estimates of the energy density reached and its dependence on the atomic mass number of the projectile.     

New scaling of charged particle pseudorapidity distributions at collider energies

A new scaling form is proposed for charged particle pseudorapidity (η) distributions on the basis of scaling in the mean hypothesis. Our new scaling accounts well the recent UA5 data of η distributions in various intervals of charged multiplicity for non single-diffractive events at energies \(\sqrt s = 200\) and 900 GeV. Similar scaling of inclusive η distributions is theoretically derived, and the validity of this scaling is assured in comparison with the data of ISR and collider energies.     

Multiplicity distributions in hadronic and heavy ion reactions

It is shown that the study of multiplicity distributionsP(n) can provide valuable information about the reaction mechanism of strong interactions. The relation betweenP(n) and Bose-Einstein correlations is discussed and the recent Na³⁵ results are interpreted as possible evidence for the existence of a chaotic and a coherent component inP(n). An experiment to test the coherent nature of pion beams is proposed.     

Multiplicity distributions and double scattering effects in π−d interactions at 205 GeV

Multiplicity distributions of charged secondaries, σ_N(π^?d) are obtained. The effective multiplicities σ_N(π^?n) and σ_N(π^?p) are extracted using the measured spectator momentum. The probability of double scattering P_N is found to be independent of multiplicity.     

Multiplicity of charged particles π− interactions on nuclei at 40 GeV/c

Multiparticle production in π^?-nucleus interactions at 40 GeV/c (Fifth Joint CERN-Serpukhov Experiment) has been studied using a spark-chamber technique at the Serpukhov accelerator. The mean multiplicities, the pseudorapidity distributions and the dispersion of the multiplicity distributions of charged particles produced on C, Al, Cu and Pb targets are presented. The data have been analysed, both subtracting and including secondary protons with p < 1 GeV/c. In the region of pseudorapidity η > 3.4 the average multiplicity is nearly independent of the size ($\text{ν}$) of the target nucleus, while it increases for η < 3.4. In the forward direction (η > 4) the mean multiplicity on nuclei is smaller than the mean multiplicity on hydrogen. The dependence upon $\text{ν}$ in the target fragmentation region is stronger when the emitted protons are included in the pseudorapidity distributions of the secondary particles. The dispersion of the multiplicity distributions for the different nuclear targets versus the mean multiplicity shows the same slope as found by the world statistics on hydrogen and by other experiments on nuclei at different energies. The results are compared with the predictions of the coherent tube model and with the soft hadron-nucleus collision model.