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Experiemntal data obtained by using the 2-m propane bubble chamber of the Joint Institute for Nuclear Research (JINR, Dubna) are used to study the effect collision centrality on the spectra of Λ hyperons and KS0 mesons produced in carbon-carbon interactions at 4.2 A GeV/c. The multiplicity of participant protons having momenta in excess of 300 MeV/c is taken to be a measure of collision centrality. The features of pions and protons accompanying strange-particle production are also presented. The experimental data in question are compared with the prediction of a modified version of the FRITIOF model. It is shown that strange particles are predominantly produced in central and semicentral collisions. The average kinematical features of KS0 mesons are found to be indepedent of collision centrality. At the same time, the average transverse momentum of Λ hyperons and the average value of their emission angle increase slowly with increasing degree of collision centrality. The anisotropy of the angular distributions of both Λ hypersons and KS/0 mesons in the c.m. frame of nucleon-nucleon collisions decreases with increasing collision centrality. The average transverse momentum of KS0 mesons is approximately 1.6 times higher than the average transverse momentum of π− mesons.

Directed (in-plane) flows of protons, pions, and projectile light fragments (d, t, 3He, 4He) have been observed by investigating the dependence of the mean transverse momentum in the reaction plane 〈px〉 on the rapidity y in the c.m. system for CC collisions at a momentum of 4.2 GeV/c per nucleon. The comparison of our in-plane-flow results of protons with flow data for various projectile/target configurations was made using the scaled flow Fs = F/(AP1/3 + AT1/3). Fs demonstrates a common scaling behavior for flow values from different systems. From azimuthal distributions of protons and π− mesons, out-of-plane (squeeze-out) flow effects have been observed and the parameter a2 (the measure of the anisotropic emission strength) has been extracted. The quark-gluon string model reproduces the experimental results quite well.

Collective flows of protons and negative pions have been studied in ${}^{2}$H $+$ C, Ta and He $+$ C, Ta collisions at an energy of 3.4 GeV/nucleon. The data have been obtained by the 2-m Propane Bubble Chamber (PBC-500) at JINR. It is found that the directed flow of protons and \ensuremath{\pi}${}^{\ensuremath{-}}$ mesons characterized by $d\ensuremath{\langle}{P}_{x}\ensuremath{\rangle}/d(y)$ increases with increase of the mass numbers of colliding nucleus pairs; the elliptic proton flow points out of the reaction plane and also strengthens as the system mass increases; the negative pion directed flow is in the same reaction plane as the proton flow for the lighter (${}^{2}$H $+$ C, He $+$ C) systems and in the opposite direction for the heavier (${}^{2}$H $+$ Ta, He $+$ Ta) systems. In ${}^{2}$H $+$ C, He $+$ C, C $+$ C, C $+$ Ne, ${}^{2}$H $+$ Ta, He $+$ Ta, C $+$ Cu, and C $+$ Ta collisions, the linear dependence of directed and elliptic flow parameters from mass numbers of projectile and target nuclei, (${A}_{P}$\ifmmode\cdot\else\textperiodcentered\fi{}${A}_{T}$)${}^{1/2}$, is similar for protons while for \ensuremath{\pi}${}^{\ensuremath{-}}$mesons the dependence of directed flow parameters is stronger. The ultrarelativistic quantum molecular dynamical model (URQMD) enlarged by the statistical multifragmentation model (SMM) satisfactorily describes the obtained experimental results for all pairs of nuclei. The data for such asymmetric nuclear collisions are obtained, to the best of our knowledge, for the first time.

The slopes of the noninvariant center-of-mass energy spectrum of negative pions in inelastic collisions of {ital d}, {alpha}, C nuclei with C and Ta targets at 4.2{ital A} GeV/{ital c} are studied. The temperatures of the negative pion are obtained using the Boltzmann distribution. The two-temperature shape of c.m. energy spectra is observed. The values of temperature do not depend significantly both on collision centrality'' and on atomic weight of the projectile nuclei. The experimental results are compared with the quark-gluon string model. The influence of resonances and directly produced pions on temperature values is studied.

Two-particle azimuthal correlations are studied in 4.2 GeV/{ital c} per nucleon {ital d}C, {alpha}C, and CC collisions with a propane bubble chamber at JINR Dubna Synchrophasotron. It is found that the azimuthal correlations are different for different pairs of secondary particles, and that they also depend on the mass of the projectiles and the collision centrality. The majority of the observed characteristics can be accounted for by the kinematic correlations calculated from the model of independent nucleon-nucleon collisions. The only exception is the effect of close pairing of like particles considered to be due to the identical particle effect for pion pairs and to short-range strong interactions for proton pairs.

Scanning results ofp, d, he, and12C interactions on Ta plates and in propane are presented. Inelastic cross sections are determined. They agree with geometrical models. General characteristics of pion multiplicity distributions are analyzed and compared with results from nucleon-nucleon interactions. Average multiplicities of negative pions are found to depend on the number of interacting beam nucleons.

The analysis of the data on the production of Λ hyperons and π- in4He−Li,12C−C,12C−Ne and16O−Ne at 4.5 A GeV/c and12C−C collisions at 4.2 A GeV/c are presented. Kinematical features of Λ's are shown to depend on the collision centrality in contrast to the stable behaviour of the pion characteristics. The correlation between the characteristics of Λ's and accompanying pions is observed. The effects seem to be incompatible with the intranuclear cascade approach. The data suggest the formation of a fully stopped and thermalized hot source in central nucleus-nucleus collisions, in which Λ hyperons are produced.

Light ion collisions with carbon target at 4.2 GeV/c/N are studied. Pion multiplicity distributions, momentum and angular spectra are analysed. These data are described in terms of models assuming independent interactions of nucleons from the projectile nucleus with the target.

Two-particle rapidity correlations are studied in {ital d}C, {alpha}C and CC interactions at 4.2 GeV/{ital c} per nucleon using 2 m propane bubble chamber. The influence of collision centrality on the short-range correlation strength is also analyzed. Comparison with the Dubna intranuclear cascade model indicates that the independent nucleon-nucleon collisions may account for the observed correlations.

The influence of collision centrality upon mean kinematic characteristics and spectra of participant protons d+C, ..cap alpha..+C, and C+C interactions at 4.2 GeV/c per nucleon is analyzed. The net charge Q of secondary particles is used as a measure of collision centrality. An increase in of participant protons with increasing Q is observed for all types of interactions analyzed. The net charge is also seen to affect the form of the rapidity spectra of participant protons in C-C interactions. The intranuclear cascade model cannot explain the dependence of these proton characteristics upon Q.