Scaled factorial moment analysis for the multiplicity distribu- tions of shower particles in the pseudorapidity phase space has been done. An evidence for the presence of dynamical uctuations has been shown for the non-peripheral interactions of28Si+Ag(Br) at 14.6 A GeV/c and 4.5 A GeV/c.The results have been compared with the values obtained from data sample calculated by cascade-evaporation model.

The nuclear emulsion was exposed at CERN by the lead projectile at 160 A GeV. The angles between any pair of fragments with Z= 2–4 have been measured in the emulsion plane for the events which did not contain heavy fragments. The constant characterizing the normal angle (φ) distribution of the fragment momentum projection onto the emulsion plane with respect to initial projectile momentum p0 is found to be σφ= (0.37 ± 0.02) mrad. Corresponding value σ0= (121 ± 6) MeV/c of nucleon momentum distribution in the lead nucleus coincides with that expected from Fermi momentum distribution for this nucleus. The peak in the pair-angle distribution of double-charged fragments, 8Be → 2α, is presented for the region of small angles (<0.1 mrad). The fraction of α-particles coming from the decay of the ground state 8Be is found to be (13 ± 2)% of their whole number.

We present the results of a study performed on the interactions of 10.6A GeV gold nuclei in nuclear emulsions. In a minimum bias sample of 1311 interac- tions, 5260 helium nuclei and 2622 heavy fragments were observed as Au projec- tile fragments. The experimental data are analyzed with particular emphasis of target separation interactions in emulsions and study of criticalexponents. Multiplicity distributions of the fast-moving projectile fragments are inves- tigated. Charged fragment moments, conditional moments as well as two and three -body asymmetries of the fast moving projectile particles are determined in terms of the total charge remaining bound in the multiply charged projectile fragments. Some differences in the average yields of helium nuclei and heavier fragments are observed, which may be attributed to a target effect. However, two and three-body asymmetries and conditional moments indicate that the breakup mechanism of the projectile seems to be independent of target mass. We looked for evidence of critical point observable in finite nuclei by study the resulting charged fragments distributions. We have obtained the values for the critical exponents gamma, beta and tau and compare our results with those at lower energy experiment (1.0A GeV data). The values suggest that a phase transition like behavior, is observed.

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 bNA, that is mean impact parameter between the participating projectile nucleons and the center of the target nucleus

Using emulsion detectors a transverse-momentum analysis of projectile fragments has been performed in Au induced nuclear interactions at 11.6 A GeV/c. Evidence for collective flow of the projectile fragments has been obtained. Angular distributions of the principal vectors of projectile and target fragments have shown strong azimuthal correlation.

The complete charge distribution of products from Au nuclei fragmenting in nuclear emulsion at 10.7A GeV has been measured. Multiplicities of produced particles and particles associated with the target source are used to select peripheral and central events. A statistical analysis, based on event-by-event charge distributions, show that a population of subcritical, critical and supercritical events, i.e. a phase transition like behaviour, is observed among peripheral collisions.

We analyse the multifractal structure of moments Gq in terms of a new variable X on data of 197Au, 32S and 16O induced interactions with emulsion nuclei and Monte Carlo generated samples. The dynamical properties of the produced particles are mapped onto multifractal spectra. We compare ln ⟨G⟩ in experimental data of 197Au, 32S and 16O with pure statistical fluctuations. It is shown that the stochasticity plays an important role for the G-moments.

The experimental data on the interactions of 10.6A GeV gold nuclei in nuclear emulsions are analyzed with particular emphasis of target separation interactions and study of critical exponents. Charged fragment moments, conditional moments as well as two and three – body asymmetries of the fast moving a Present address: McGill University, Department of Physics,

In this talk we will present some of the recent results from the experiments E853 and EMU12 using the BNL AGS Au-beam at 11.6 A GeV/c and the CERN SPS PB-beam at 158 A GeV, respectively. Aspects on the particle production and on projectile break-up will be discussed. The results are compared with model expectations.

Results on charged particle multiplicities, densities and fluctuations from central Pb+Pb interactions at 158 A GeV are presented and discussed.

The anomalous behavior of 2-dimensional scaled factorial moments for charged hadrons in nucleus-nucleus collisions is studied in some detail using both mini-bias and central collision data of O-16- and Au-197-Em interactions from EMU01 experiment. The analysis is carried out in terms of Hurst exponents, suggesting the necessity of different partitions in pseudo-rapidity and azimuthal angle. The results can be interpreted tentatively as due to the superposition effect in nucleus-nucleus collisions.

Angular distributions of projectile-associated He fragments from Pb induced reactions on stationary Pb target at 158 A GeV/c incident momentum are reported. The precision of the angular measurements was about ±0.01 mrad. Two emission components are appearing in the projected angular spectra of the He particles, one representing fragmentation at Fermi momentum scale, while the other one exhibits large transverse momentum transfer. By scaling with the incident momentum the angular spectra of He particles are compared with earlier reported measurements of Au on Au interactions at 11.6 A GeV/c. The pT spectrum of the He particles appears the same for the two cases.

The anomalous behavior of 2-dimensional factorial moment in nucleus-nucleus collisions is studied in some detail using both mini-bias and central collision data of O-, Sand Au-Em interactions from EMU01 experiment. The correct value for the effective Hurst exponent in the analysis of higher-dimensional factorial moment is found to be greater than unity, showing clearly the existence of superposition effect in nucleus-nucleus collisions.

An equation is presented, which allows us to calculate the dependence of the multiplicity of the particles produced in nucleus-nucleus collisions, [n(pi)](AA), on an experimentally measured value Q/Z(pr), which is strongly correlated to the impact parameter b. The equation combines data from a wide range of projectile masses (A(pr) = 6-197) over a large momentum region (P-pr = 4-200 A GeV/c). The possible meaning of the parameters is discussed in the context of a simple geometrical model.

The mechanism for producing slow, target associated particles in high energy heavy ion collisions is investigated. It is shown that the same mechanism which was proposed for hadron induced interactions is likely to appear also for heavy-ion reactions. The results indicate however a much weaker correlation between impact parameter and yield of slow particles.

The fragmentation topology of28Si at 3.7A GeV and 14.6A GeV and32S at 200A GeV in reactions with emulsion nuclei is presented. The fragmentation cross sections are very similar at all three energies. A statistical percolation model can qualitatively describe the data forZ≥ 6. The He production is underestimated and the 3 ≤Z ≤ 5 fragments overestimated by this model.

EMU01 experiments tracking high energy heavy-ion interactions with nuclear emulsion detectors are performed at the BNL AGS and the CERN SPS. Some unique measurements are presented. As an illustration impact parameter selections, projectile fragmentation and particle production are discussed. Recent results from gold nucleus reactions at 11 A GeV are given.

Basic data are presented on the parameters of fragmentation, multiplicities and angular spectra of low energetic targed associated particles in the interction of 197Au nuclei of 10.7A GeV.

Charged particle pseudorapidity density distributions in Au induced reactions in nuclear emulsion at 10.7 A GeV have been measured. In peripheral events the shower particle distribution exhibits a two peak structure while in central collisions it has a Gaussian shape. The spectator protons appear in the second peak in the pseudorapidity spectra and exhibits a broader momentum distribution than expected from Fermi motion. The produced particle yield in central collisions is not substantially different from phenomenological descriptions based on data from O and S induced reactions.

Pseudorapidity density and multiplicity distributions of charged particles produced in heavy-ion collisions at the BNL AGS have been studied. The multiplicity distributions and pseudorapidity distributions of shower particles in Au-induced interactions are presented and compared with model predictions from RQMD, FRITIOF and VENUS. It is shown that the widths of the pseudorapidity distributions of produced particles in central collisions are independent of the interacting system. The results from EMU01 have been compared, and found to agree, with the results from two other heavy-ion experiments, E802 and E814.