Carbon nucleus breakup induced by incident protons, deuterons, a particles, and carbon nuclei with a momentum of 4.2 GeV/c per nucleon is investigated. The mean multiplicities, emission angles, and momentum characteristics of secondary particles are measured as functions of the atomic weight of the projectile nucleus. These data are compared with the features of inelastic pC, dC, alpha C, and CC collisions. At least two mechanisms of nucleus-nucleus interactions-the nuclear cascade and the evaporation of target fragments-are found to contribute to the breakup of carbon nuclei.

Collisions of carbon nuclei with hydrogen are selected from inelastic interactions of C-12 nuclei in propane (C3H8) at p(0) = 4.2 GeV/c per nucleon. The yields of spectator protons, deuterons, tritons, and fragments with z greater than or equal to 2 are measured, and their transverse-momentum distributions are studied in the laboratory frame and in the frame where the total transverse momentum of charged fragments is zero.

New experimental data on the relative yields and on the momentum and correlation characteristics of various C-12 spectator fragments formed in C-12 collisions with propane (C3H8) and tantalum nuclei at a primary momentum of 4.2 GeV/c per nucleon are presented and discussed. The cross sections for the production of spectator protons, deuterons, and tritons and their momentum distributions are studied as functions of the target mass number and impact parameter of a nucleus-nucleus interaction. It is shown that some of these dependences weaken or disappear in going over to the rest frame of a residual nucleus undergoing fragmentation. This means that the dependences in question are associated with its decay in flight.

The coherent dissociation C-12 --> 3 alpha on a carbon target at an incident momentum of 4.2 GeV/c per nucleon is observed, and its cross section is estimated. The dependence of the cross section on the target mass number is investigated. The momentum characteristics and correlations of a particles from coherent dissociation as observed in the laboratory system and in the rest frame of the nucleus undergoing fragmentation are compared with those for incoherent transitions and those for heavier target nuclei. The mechanism of the dissociation C-12 --> 3 alpha is shown to depend strongly on the target mass number and on the character of nucleus-nucleus interaction.

Target and centrality dependence of pion and proton distributions is studied in C+C and C+Ta collisions at 4.2 GeV/c per nucleon using the 2-m propane bubble chamber. The experimental data are compared with the predictions of the Monte Carlo quark-gluon string model (QGSM). The pion and proton transverse momentum spectra at midrapidity are well described by the two-component thermal model. The shape of the proton rapidity distribution strongly depends on the collision centrality and reflects the stopping power of colliding nuclei. The pion rapidity distribution is Gaussian in shape regardless of the target mass number and collision centrality. The QGSM completely reproduces main features of pion and proton rapidity spectra as well as pion transverse momentum spectra. The model does not fully reproduce the features of the proton transverse momentum spectra.

The rapidity distributions of pi(-) mesons in different transverse-momentum intervals are analyzed for dTa, alpha Ta, and CTa collisions at 4.2 GeV/c per projectile nucleon. The effect of the target atomic weight on the rapidity and transverse-momentum distributions of pi(-) mesons is probed by comparing data on CC and CTa collisions. Data on CTa collisions are confronted with predictions of the quark-gluon string model. The model qualitatively reproduces the observed distributions of pi(-) mesons and provides a satisfactory quantitative description of the ratio of pi(-) yields in CTa and CC collisions as a function of the transverse momentum p(t) for p(t) < 0.5 GeV/c.

Rapidity distributions of protons in pC, dC, alpha C, and CC collisions at a projectile momentum of 4.2 GeV/c per nucleon are analyzed at various transverse momenta. The data is compared with the predictions of the quark-gluon string model. This model is shown to provide a satisfactory description of inclusive proton distributions in basic kinematic variables. The relative contributions of protons from Delta-isobar decays and of protons directly produced in NN interactions to the rapidity distributions at various transverse momenta are estimated by invoking the quark-gluon string model.

The invariant cross sections of the proton yield are presented as a function of the kinetic energy (T > 0.4 GeV) at fixed angles from 0 to 90-degrees for (p,d,alpha,C) + C and (d,alpha,C) + Ta interactions at 4.2 GeV/c per nucleon. It is shown that in the interactions of light nuclei with carbon and tantalum nuclei, the shape of the proton spectra in the studied energy range for emission angles theta > 30-degrees is independent of the type of projectile nucleus. The shape of the spectra of protons with energy T > 0.4 GeV is independent of the type of target nucleus, starting from theta = 20-degrees. The proton-yield cross sections at fixed angles were studied as functions of the atomic weights of the colliding nuclei (A(P),A(T)). In each angular range, the dependence of dsigma/dOMEGA on A(P) can be represented by the power function A(P)alpha(P) for interactions on both light and heavy targets. The angular dependences of the parameters alpha(P)C and alpha(P)Ta are obtained. For the power dependence of dsigma/dOMEGA on the atomic weight of the target nucleus, A(T)alpha(T), the parameters alpha(T) increase from approximately 0.5 to 1-1.1 as the angle theta increases from 0-degrees to 90-degrees.

Invariant proton-production cross sections are reported as a function of the kinetic energy over the interval 50-400 MeV at fixed angles from 0 to 180-degrees for (p, d, alpha, C) + C and (d, alpha, C) + Ta interactions at 4.2 GeV/c per nucleon. In interactions of the light nuclei with carbon nuclei, the shape of the proton spectrum is independent of the nature of the projectile nucleus at emission angles theta > 30-degrees in the studied energy interval. In collisions of (d, alpha, C) with tantalum nuclei the spectra of protons with theta > 20-degrees are similar in the two regions 50-200 and 200-400 MeV, while the slope parameters are different. The atomic weight of the target nucleus has an important effect on the shape of the proton spectra at 50 less-than-or-equal-to T < 200 MeV and theta < 90-degrees, while the shape of the spectra of faster protons (200 less-than-or-equal-to T less-than-or-equal-to 400 MeV) becomes independent of A(T) above theta = 20-degrees. The proton-production cross sections have been studied as a function of the atomic weights of the colliding nuclei at fixed angles. In each angular interval, the A(p) dependence of dsigma/dOMEGA can be described by a power law (A(p)alpha(p)) for interactions with both light and heavy targets. The angular distributions of the parameters alpha(p)C and alpha(p)Ta have been found. With a power-law dependence of dsigma/dOMEGA on the atomic number of the target nucleus (A(T)alpha(T)), values alpha(T)d,alpha,C almost-equal-to 1 are found at theta < 50-degrees. They increase to approximately 1.5 in the interval 120-degrees less-than-or-equal-to theta less-than-or-equal-to 180-degrees.

The slopes of the noninvariant center-of-mass energy spectrum of negative pions in inelastic collisions of d, alpha, C nuclei with C and Ta targets at 4.2A GeV/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 axe 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/c per nucleon dC, 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.

Invariant cross sections for the yield of pi--mesons are given as functions of the meson kinetic energy at fixed angles in intervals from 0 to 180-degrees for d Ta, alpha-Ta, and CTa interactions at 4.2 GeV/c per nucleon. It is shown that the shape of the pion spectra above 0.1 GeV and at emission angles-theta > 20-degrees does not depend on the type of projectile nucleus, within the approximately 10% errors. The pi- yield cross sections at fixed angles have been investigated as functions of the atomic weights of the colliding nuclei. In each angle interval, the dependence of d-sigma(pi-)/d-OMEGA on the atomic weight of the projectile can be approximated by a power-law function (A(alpha)) for interactions on both light and heavy targets. The parameter a is close to unity at small angles and decreases to alpha almost-equal-to 2/3 at angles-theta greater than or similar to 130-degrees. In the power-law dependence of d-sigma(pi-)/d-OMEGA on the atomic weight of the target nucleus (A(T)alpha-T), the parameter alpha(T), increases from 0.6 in the interval theta less-than-or-equal-to 10-degrees to almost-equal-to 1 for theta > 90-degrees.

In this article we analyze distributions in total energy and also in the transverse and longitudinal momenta in the c.m.s. of {pi}{sup 0} mesons, obtained on the basis of the corresponding {gamma}-ray distributions for CTa and multinucleon CC interactions at 4.2 GeV/{ital c}. The {pi}{sup 0} -meson distributions established are compared with the experimentally obtained spectra of {pi}{sup {minus}} mesons for the same types of interactions.

In interactions of 4.2-GeV/{ital c} protons with carbon nuclei and of 10-GeV/{ital c} protons with carbon and tantalum nuclei the characteristics of secondary protons and {pi}{sup {minus}} mesons have been investigated as a function of the energy of the leading proton. Leading-proton spectra are presented. The rates of energy loss of a nucleon in nuclear matter are estimated.