F.G. Lepekhin

A study of inelastic pion-nucleus interactions at 200 GeV/c in an emulsion

Abstract Results from a study of π-nucleus interactions in emulsion, at an incident momentum of 200 GeV/c are presented and discussed. Some characteristics of heavy and shower-particle multiplicity distributions are reported and compared with the results from p-nucleus collisions at the same momentum. The angular distributions of shower particles are reported and analyzed in detail. It is shown, particularly, that one-particle distributions, being plotted in terms of pseudorapidity, have a bimodal structure in πA interactions. Also, pseudorapidity and azimuthal two-particle correlations are investigated. Considerable attention has been devoted to the exclusion of kinematical and trivial correlations. A qualitative comparison of the data with predictions of some model approaches has been performed.

Investigation of inelastic interactions of 400 GeV protons with emulsion nuclei

Abstract The basic experimental characteristics of incoherent interactions of 400 GeV protons on emulsion nuclei, such as the multiplicity of charged secondaries, one-particle distributions and two-particle correlations, are reported and discussed in details. They are compared with the results of other experiments on hadron-nucleus interactions at lower energies. We have shown from both the quantitative and qualitative comparison of the data presented with predictions of various model approaches to nuclear production, that most of them cannot explain the complete set of experimental observations. An analysis of the experimental data presented gives strong support to the idea that the production mechanism in high-energy hadron-nucleus interactions has two or multi-component character.

Topology of “white stars” in the relativistic fragmentation of light nuclei

Experimental observations of the multifragmentation of relativistic light nuclei by means of emulsions are surveyed. Events that belong to the type of “white stars” and in which the dissociation of relativistic nuclei is not accompanied by the production of mesons and target-nucleus fragments are considered. An almost complete suppression of the binary splitting of nuclei to fragments of charge in excess of two, Z > 2, is a feature peculiar to charge topology in the dissociation of Ne, Mg, Si, and S nuclei. An increase in the degree of nuclear fragmentation manifests itself in the growth of the multiplicity of singly and doubly charged fragments (Z = 1, 2) as the charge of the unexcited fragmenting-nucleus part (which is the main part) decreases. Features of the production of systems formed by extremely light nuclei α, d, and t are studied in the dissociation of the stable isotopes of Li, Be, B, C, N, and O to charged fragments. Manifestations of 3He clustering can be observed in “white stars” in the dissociation of neutron-deficient isotopes of Be, B, C, and N.

Fragmentation of 22Ne in emulsion at 4.1A GeV/c

Charge distributions of projectile fragments produced in the interactions of 22Ne beams with emulsion at 4.1A GeV/c have been studied. Correlations between projectile and target fragments and among projectile fragments are presented. The change of charge yield distribution with the violence of the collision has been shown. The present analysis contradicts theoretical calculations describing the inclusive charge yield distribution of fragments by a single process.

Coherent production of particles by 67 GeV/c protons on emulsion nuclei

Abstract In the study of interactions of 60 GeV/c π− mesons in nuclear emulsion some peculiarities of the prong-number distribution and the angular distribution of secondaries have been observed. They are interpreted in terms of the coherent production of three and five pions on emulsion nuclei. The cross section for these reactions increases with the increasing energy.

Diffractive coherent production in interactions of 400 GeV/c protons on emulsion nuclei

Abstract Data on coherent diffractive dissociation of 400 GeV/c protons on emulsion nuclei are presented. Measurements were made of total and topological cross sections as well as of cross sections of the exclusive channels p → pπ+π− and p → p2π+2π−. The energy dependence of some basic characteristics (cross sections, multiplicity of the diffractively excited system) of such reactions in the range 20–400 GeV is discussed and it is observed that these dependences are the same qualitatively for both the diffractive and non-diffractive components of multiparticle production.