M. Zafar

INTERMITTENCY IN 4.5A AND 14.5A GeV/c28Si-NUCLEUS INTERACTIONS

The occurrence of intermittent patterns in 14.5A GeV/c28Si-nucleus interactions is examined in terms of Scaled Factorial Moments (SFMs), introduced by Bialas and Peschanski. Further, to examine the dependence of various interesting characteristics of SFMs on incident energy, the data on 4.5A GeV/c28Si-nucleus collisions available in our laboratory are analyzed. Interestingly, log-log plots between rapidity interval δη and the qth order factorial moment Fq for both the energies exhibit linear behavior indicating thereby the presence of intermittency in the interactions investigated. Moreover, to look at the fractal nature of the particle emitting sources, variation of the fractal dimensions, dq with the order of the moment is investigated. Finally, study of the variation of λq [=(ϕq+1)/q)] with the order of the moment, q indicates a possibility of non-thermal phase transition in certain types of events

Forward?backward multiplicity fluctuations in 200A?GeV/c?16O?AgBr and 32S?AgBr collisions

Charged particle multiplicity correlations and fluctuations in forward?backward symmetric pseudorapidity windows of varying widths and positions are investigated by analysing the experimental data on 16O?AgBr and 32S?AgBr collisions at 200A?GeV/c. These results are compared with the predictions of the Monte Carlo models HIJING and AMPT and also with those reported at RHIC energies. The findings indicate the presence of strong short-range correlations which might arise due to isotropic decays of cluster-like objects either in the forward or backward pseudorapidity region. The analysis of the mixed events further confirms that the observed correlations are a distinct feature of the data, which vanish after mixing the events.

SOME FEATURES OF INELASTIC INTERACTIONS OF 28Si AND 12C IONS IN NUCLEAR EMULSION AT 4.5A GeV/c

Multiplicity distributions of various types of tracks produced in inelastic interactions of 28Si and 12C at 4.5A GeV/c with nuclear emulsion nuclei have been investigated. The correlations of the type where Ni, Nj=Ng, Nb, Nh or Ns with i≠j have been studied and compared with the results from p-Em interactions at the same momentum per nucleon. Some saturation effects in the values of with Ng are observed. Furthermore, some of these correlations show almost similar dependence in nucleus-nucleus and proton-nucleus interactions at same per particle momenta. The values of have been obtained by subtracting the contribution of Z=1 fragments to the observed showers. The dependence of so obtained on the number of interacting projectile nucleons shows that the nucleus-nucleus collisions at these energies can be interpreted in terms of multiple N-N collisions.

CLUSTER PRODUCTION IN 14.5A GeV/c Si-NUCLEUS COLLISIONS

Characteristics of clusters of relativistic charged secondaries produced in 14.5A GeV/c Si-nucleus collisions are investigated by examining the behaviour of the rapidity gap distribution. The findings reveal that the maximum number of relativistic charged particles constituting a cluster is four. Further, the size of the cluster is observed to remain essentially independent of the mass of the struck nucleus. A comparison of the result of the present study with those reported earlier for hadron-hadron and hadron-nucleus collisions indicates that similar mechanisms may operate in the production of secondary particles in both hadronic and nuclear collisions at high energies.

Entropy Analysis in Relativistic Heavy-Ion Collisions

Entropy creation in multiparticle system is investigated by analysing the experimental data on ion-ion collisions at AGS and SPS energies and the results thus obtained are compared with those predicted by multiphase transport and correlation-free Monte Carlo models. Entropies produced in limited- and full-phase space are observed to increase with increasing beam energy. The entropy values, normalized to the maximum rapidity and plotted against pseudorapidity (bin width also normalized to the maximum rapidity), are found to be energy independent, exhibiting a kind of entropy scaling. Such scaling is observed in the full phase space as well as in the regions confined to the forward or backward hemispheres. The findings also reveal that there exist strong correlations amongst the particles produced in the forward and backward hemispheres around the midrapidity. These correlations are found to be of short range in nature, and the contributions from the long-range correlations seem to be absent. PACS numbers: 25.75-q, 25.75.Gz.

SHORT- AND LONG-RANGE MULTIPLICITY CORRELATIONS IN RELATIVISTIC HEAVY-ION COLLISIONS

Forward–backward (FB) charge correlations are investigated by analyzing experimental data on 16O–AgBr interactions at 14.5A, 60A and 200A GeV. Findings are compared with the predictions of Monte Carlo model, heavy-ion jet interaction generater (HIJING). The results reveal that the observed correlations are mainly of short-range type, which arise due to the decay of clusters and/or resonances produced in the central rapidity region. The range of FB correlations are observed to extend with increasing beam energy. However, there is no evidence for the presence of long-range correlations even at the highest incident energy considered.

Angular distribution of slow and relativistic charged particles produced in silicon- and carbon-emulsion interactions at 4.5A GeV/c

SummaryThe paper presents the data on28Si- and12C-emulsion interactions at 4.5A GeV/c. Angular distributions of target fragments and relativistic charged secondaries have been investigated. No shock wave phenomenon is observed. Forward/backward ratios in each case are calculated. A detailed study of probability distributions of relativistic charged secondaries produced per unit rapidity as well as rapidity densities and their dependence on projectile and target mass has been carried out. A comparative study of angular spectra of shower particles produced in central and peripheral collisions gives an evidence in support of limiting fragmentation hypothesis. It is found that a large number of particles are produced in the central region in comparison with the target fragmentation region, whereas no indication of particle production is found in the projectile fragmentation region. Moreover, the centrality of the interactions seems to increase with the increasing shower particle multiplicity.

RAPIDITY CORRELATIONS IN PARTICLES PRODUCED IN INELASTIC COLLISIONS OF 12C AND 28Si IONS IN EMULSION AT 4.5A GeV/c

Correlations between particles produced in the interactions of 28Si and 12C nuclei with emulsion nuclei at 4.5A GeV/c has been investigated. 701 events of 28Si and 844 of 12C interactions have been analysed. A method which combines techniques from the method of using the two-particle correlation functions and from rapidity-gap distributions is applied. This method has been used successfully by others to study the correlation in P-Em and light-ion interactions. However, we have applied it to the heavy-ion collision data. Small but significant departure from zero-correlation is observed.

Multiparticle production in 24, 50 and 400 GeV/c particle-nucleus interactions

SummarySome interesting aspects of multiparticle production in 24 and 400 GeV/c p-nucleus and 50 GeV/c π--nucleus collisions have been studied. The correlations of fast target protons with evaporated and shower particles produced in these interactions have been thoroughly investigated. The results reveal that the average number of shower particles produced in these interactions is in marked disagreement with the values predicted by the simple independent-particle and hydrodynamical models. Finally, on invoking the additive quark model, the mean normalized multiplicitiesR4 andR5 are observed to be independent of the nature of the projectile indicating a new kind of scaling in hadron-nucleus interactions.RiassuntoSono stati studiati alcuni aspetti interessanti della produzione di molte particelle in collisioni p-nucleo a 24 e 400 GeV/c e π--nucleo a 50 GeV/c. Sono state studiate esaurientemente le correlazioni dei protoni veloci del bersaglio con particelle evaporate e dello sciame prodotte in queste interazioni. I risultati rivelano che il numero medio di particelle prodotte in queste interazioni è in marcato disaccordo con i valori previsti dal modello semplice delle particelle indipendenti e da quello idrodinamico. In fine, chiamando in causa il modello additivo dei quark si osserva che le molteplicità medie normalizzateR4 eR5 sono indipendenti della natura del proiettile indicando un nuovo tipo di variazione di scala nelle interazioni adrone-nucleo.РезюмеИсследуются некоторые интересные аспекты множественного рождения частиц при соударениях протонов, имеющих импульсы 24 и 400 ГэВ/с, с ядрами и π- мезонов, имеющих импульс 50 ГэВ/с, с ядрами. 0 Изучаются корреляции быстрых протонов мишени с испарительными и ливневыми частицами, образованными в этих взаимодействиях. Полученные результаты показывают, что среднее число ливневых частиц, образованных в этих взаимодействиях существенно отличается от величин, предсказанных с помощью простой модели независимых частиц и с помощью гидродинамической модели. Используя аддитивнчю кварковую модель, показывается, что средние нормированные множественностиR4 иR5 не завизят от природы налетающих частиц, что указывает на новый тип скейлинга в адрон-ядерных взаимодействиях.

Production of energetic he nuclei and tritons in 24 GeV/c proton interactions with Ag and Br nuclei

Summary708 stars withNh⩾7 have been analysed to study the production mechanism of fast He nuclei and tritons. On the basis of the