Study of the peculiarities of multiparticle production via event-by-event analysis in asymmetric nucleus-nucleus interactions

Anastasiya Fedosimova,Adigam Gaitinov,Ekaterina Grushevskaya,Igor Lebedev,B Pattison

doi:10.1051/epjconf/201614519009

Anastasiya Fedosimova, Adigam Gaitinov + Show 3 more

Open Access

https://doi.org/10.1051/epjconf/201614519009

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Abstract

In this work the study on the peculiarities of multiparticle production in interactions of asymmetric nuclei to search for unusual features of such interactions, is performed. A research of long-range and short-range multiparticle correlations in the pseudorapidity distribution of secondary particles on the basis of analysis of individual interactions of nuclei of 197 Au at energy 10.7 AGeV with photoemulsion nuclei, is carried out. Events with long-range multiparticle correlations (LC), short-range multiparticle correlations (SC) and mixed type (MT) in pseudorapidity distribution of secondary particles, are selected by the Hurst method in accordance with Hurst curve behavior. These types have significantly different characteristics. At first, they have different fragmentation parameters. Events of LC type are processes of full destruction of the projectile nucleus, in which multicharge fragments are absent. In events of mixed type several multicharge fragments of projectile nucleus are discovered. Secondly, these two types have significantly different multiplicity distribution. The mean multiplicity of LC type events is significantly more than in mixed type events. On the basis of research of the dependence of multiplicity versus target-nuclei fragments number for events of various types it is revealed, that the most considerable multiparticle correlations are observed in interactions of the mixed type, which correspond to the central collisions of gold nuclei and nuclei of CNO-group, i.e. nuclei with strongly asymmetric volume, nuclear mass, charge, etc. Such events are characterised by full destruction of the target-nucleus and the disintegration of the projectile-nucleus on several multi-charged fragments.

Highlights

Cosmic rays,which are measured at ground stations, are a natural source of high-energy particles
To determine the primary cosmic particle parameters, a complex inverse task must be solved, because a lot of interactions happen before the observation level
Events with h > 0.64 at both small values and at large values of the pseudorapidity interval, but with h ∼ 0.5 in the middle region of dη, have been referred to the fourth type (Fig. 1 right-lower). Such behaviour of the Hurst curve corresponds to events of the mixed type, including processes of the explosive and jet types

Summary

Introduction

Cosmic rays,which are measured at ground stations, are a natural source of high-energy particles. To understand the features of the development of cascade processes, detailed information about the fluctuations of distributions of secondary particles in different types of nucleus-nucleus interactions in the elementary act, is required [1]. Anomalous events (high multiplicity, large transverse momenta, large multiparticle correlations in pseudorapidity distributions of secondary particles, etc.) can significantly change the dynamics of the cascade process. Events with h > 0.64 at both small values and at large values of the pseudorapidity interval, but with h ∼ 0.5 in the middle region of dη, have been referred to the fourth type (Fig. 1 right-lower) Such behaviour of the Hurst curve corresponds to events of the mixed type, including processes of the explosive and jet types. The emulsion technique allows us to investigate parameters of fragmentation and multiparticle processes in the same interaction

Fragmentation of the projectile nucleus

Pseudorapidity correlations

Fragments of the target nucleus

Conclusion