The behavior of the relativistic hadron (shower particle) multiplicity for 32 S-nucleus interactions is investigated. The experiment is carried out at 3.7A GeV (Dubna energy) and 200A GeV (SPS energy) to search for the incident energy effect on the interactions inside the different emulsion target nuclei. Data are presented in terms of the number of emitted relativistic hadrons in both forward and backward angular zones. The dependence on the target size is presented. For this purpose the statistical events are separated into groups according to the interactions with H, CNO, Em, and AgBr target nuclei. The separation of events, into these groups, is executed based on predictions of Glauber's multiple scattering theory. Features suggestive of a decay mechanism seem to be a characteristic of the backward emission of relativistic hadrons. The results strongly support the assumption that the relativistic hadrons may already be emitted during the de-excitation of the excited target nucleus, in a behavior like that of compound nucleus disintegration. Regarding the limiting fragmentation hypothesis beyond 1 GeV, the target size is the main parameter affecting the backward production of relativistic hadrons. The backward shower particle multiplicity can indicate the impact parameter. The incident energy is a principle factor responsible for the forward relativistic hadron production, implying that this system of particle production is a creation system. However, the target size is an effective parameter as well as the projectile size considering the geometrical concept seen in the nuclear fireball model. The forward shower particle multiplicity distributions may behave in a similar trend at Dubna energy and SPS for low target sizes. For heavy target sizes, the SPS energy reveals the creation of hadrons with nearly equal probabilities over a wide range of multiplicity, extending to more than 300 hadrons per event. The data are analyzed in the framework of the FRITIOF model.

In this work, the electromagnetic dissociation (EMD) of sulphur projectile induced by two widely differing energies in nuclear emulsions is investigated. Although the percentages of EMD events of the total numbers of studied interactions are relatively small, i.e. 5.7 and 14.4% for 3.7 and 200A GeV interactions respectively, one could extract some results out of them. The emission of a proton through the 32S(γ, p)31P channel is found to be a dominant process (43.8%) at 200A GeV whereas the single alpha emission through the 32S(γ, α)28Si channel is the dominant one (34.0%) at 3.7A GeV. Multiplicity distributions of hydrogen and helium isotopes as well as the measured probabilities for the different modes of fragmentation are studied. The comparison of the present results, from electromagnetic and peripheral nuclear interactions, indicates the effective role of the different reaction mechanisms at ultra-relativistic energy (200A GeV). The experimental inclusive cross sections of different fragmentation modes produced in the EMD of 32S ions at 200A GeV were found to be in satisfactory agreement with the predictions of the combined approach of Pshenichnov et al.

In this experiment, 32S interaction with emulsion nuclei is examined at 3.7A and 200A GeV. Backward relativistic hadron production seems to be an exact decay system, depending on the target size. For emulsion nuclei, the decay constant of this system nearly equals 1.3. Independent of the projectile size and energy, the backward relativistic hadrons are produced with probability values of ∼20%–30%. For projectile nuclei with mass numbers greater than or equal to 6 and at any incident energy, the average multiplicity of these backward hadrons tends to a saturation value of ∼0.4. Regarding the multiplicity range of forward relativistic hadrons, reaching 60 hadrons per event at 3.7A GeV and extending to ∼400 hadrons per event at 200A GeV, energy plays a fundamental role in forward relativistic hadron production. The results strongly support the assumption that relativistic hadrons are created as a result of energy from participant nucleons.

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Partial production cross sections of electromagnetic breakup of 32S projectiles at two widely differing energies were measured using an emulsion target. The electromagnetic dissociation represents about 6% and 17% of the total number of nuclear events at Elab/A = 3.7 and 200 GeV, respectively. The experimental electromagnetic cross sections σexpEMD show an energy dependence that is well reproduced by the Weizsacker–Williams approximation. The value of σexpEMD at 200A GeV (with γ >> 1) shows a good agreement with that predicted by the combined model of Pshenichnov et al. Examination of the reactions (γ, p) and (γ, He) reveals that the ratio of 1 p/1 He cross sections is close to unity at Dubna energy (3.7A GeV), while it rapidly increases to 3.0 ± 0.6 at CERN energy (200A GeV). In most of the observed dissociation modes, the total kinetic energy of the fragments in the projectile rest frame is lower than 50 MeV. Nevertheless, it is possible that the contribution of excitation modes of the different multipolarities is determining in this region. PACS No.: 25.70