[en] Short communications only

[en] Angular distributions of charged particles produced in ¹⁶O and ³²S collisions with nuclear track emulsion were studied at momenta 4.5 and 200 A GeV/c. Comparison with the angular distributions of charged particles produced in proton-nucleus collisions at the same momentum allows to draw the conclusion, that the angular distributions in nucleus-nucleus collisions can be seen as superposition of the angular distributions in nucleon-nucleus collisions taken at the same impact parameter b_NA, that is mean impact parameter between the participating projectile nucleons and the center of the target nucleus

[en] The recent status of the EMU01 experiment where nuclear emulsions are used as both target/detector material for horizontally exposed stacks and as detector for vertically exposed chamber plates is discussed. An investigation of the behaviour in the number of produced particles per participating nucleon reveal weak nonlinear effects for the most central collisions. Intermittency index can be obtained from the density distributions for S+Au and S+Ag interactions which corresponds to fractal dimensions somewhat smaller than unity

[en] The EMU01 Collaboration has employed emulsion chamber and pellicle detectors to accumulate a large database of heavy nucleus interactions. Samples include both minimum bias and central collisions, analyzed in a uniform manner to extract multiplicities and angular distributions of charged particles and nuclear fragments. We find that the main features of these distributions are well represented by geometrical superposition models. A unique feature of EMU01 is the use of emulsion chambers with thin foil targets to observe produced particle angular distributions with exceptionally high precision, permitting extension of fluctuations and correlations analyses beyond the resolution limits imposed by other experimental techniques. The data are generally well reproduced by interaction simulations such as FRITIOF (the Lund monte carlo for nuclear collisions) which include only conventional physics effects. However, the analysis of fluctuations and correlations via factorial moment and cumulant techniques yields some suggestive results which require further investigation, both by continued analysis of existing data and from Au and Pb beam exposures scheduled for the next few years. (orig.)

[en] Pseudorapidity density distributions of charged particles in heavy-ion collisions have been studied. The results from EMU01 have been compared to the results from the experiments WA80 and E802. The recently obtained pseudorapidity distributions from Au+Au and Au+Ag interactions have been compared to a linear extrapolation from lighter systems. (orig.)

[en] The multiplicity distributions of shower particles (n_s) are measured in inclusive inelastic oxygen emulsion interactions. Scaling is observed in the normalized variable n_s/< n_s> for 14.6, 60 and 200 A GeV. The dependence of < n_s> on the charge flow in the forward direction (Q_ZD) and the distribution of the number of participating projectile protons is examined. The normalized multiplicities as a function of Q_ZD seem also to be independent of incident energies. A comparison with the Lund model Fritiof yields satisfactory agreement. (orig.)

[en] The multiplicity distributions of low-energetic target-associated particles from 200 A GeV oxygen-induced interactions with emulsion nuclei are presented. The experimental distributions are compared with distributions obtained using the Ranft and Fritiof simulation codes. It is found that the intra-nuclear cascade plays an important role in ion-induced interactions, similar to what is the case for hadron-induced interactions. (orig.)

[en] In the present letter we discuss the general features of the multiplicity distributions in relativistic heavy ion collisions. It is shown that from simple statistical considerations it is possible to predict the dependence of the dispersions of multiplicity distributions on the average multiplicities in any given rapidity window. The applicability of the negative binomial distribution to multiplicity distributions from collisions with heavy ions is discussed. (orig.)

[en] We report on an experiment in which emulsion chambers were exposed to a beam of 200 A GeV ¹⁶O at the CERN SPS. Pseudo-rapidity distributions are measured with high precision. Pseudo-rapidity densities of 140 particles per unit rapidity corresponding to an energy density of about 3 GeV/fm³ are observed. Pseudo-rapidity density distributions and fluctuations are found to satisfactorily agree with the Lund Monte Carlo model Fritiof, although new and unknown sources for fluctuations might still be present. (orig.)

[en] Fluctuations in particle densities of non-statistical origin are studied in central ¹⁶O+Ag(Br) and ³²S+Au interactions at 200 A GeV. Non-statistical fluctuations in the ³²S-induced interactions seem to enhance the local particle densities, and suggest the presence of intermittancy. The fluctuations are found to be accompanied by a clustering tendency also in the azimuthal plane. A new method for the study of azimuthal correlations is proposed. (orig.)