Multiple Production And Flow Effect Of Final-State Particles Produced In High Energy Collisions

This thesis focuses on the multiple production and flow effects of particles produced in high energy collsions. Following the introduction and review chapters, three main chapters which contain our research results are given. In the last chapter, we give a summary and an outlook. The main results contained in the three main chapters are presented in the following.Firstly, the multiplicity distributions of projectile fragments emitted in interactions of different nuclei with emulsion are studied by using a multi-source thermal model (previously multi-source ideal gas model). Our calculated results show that the projectile fragments can be described by the model and each source contributes an exponential distribution. As the weighted sum of the folding result of many exponential distributions, a multi-component Erlang distribution is used to describe the experimental data. The relationship between the height (or width) of the distribution and the mass of the incident projectile, as well as the dependence of projectile fragments on target groups, are investigated too. The unified formula on multiplicity distributions of final-state particles is also used to describe a variety of experimental data including multiplicity, mass, transverse mass, excitation energy, transverse energy, and transverse momentum distributions. Experimental data of proton-antiproton, positron-proton, electron-proton, and nucleus-nucleus collisions are analyzed and found that the distributions of mentioned quantities can be described by the multi-component Erlang distribution.Secondly, to understand the emission source of the final-state particles produced in proton-nucleus and nucleus-nucleus collisions at high energies, we analyzed some experimental data of angular distributions by using the multi-source thermal model. The deformation and the movement of the emission source are considered in the model, and the method of Monte Carlo simulation is performed. We show that the calculated results are in agreement with the experimental data. Our results show that the emission source has a deformation and/or movement in the transverse plane (off-reaction plane). Furthermore, elliptic flows of charged particles produced in nucleus-nucleus collisions at high energy are studied in the model. The participant nucleon number at a fixed impact parameter is calculated by a geometrical picture of the participant-spectator model. Then, the dependence of elliptic flow on participant nucleon number is obtained in the combined framework of the two models. Our calculated results are approximately in agreement with the experimental data of the PHENIX Collaboration.Thirdly, in a wide energy range, the dependences of charged particle pseudorapidity distributions on impact parameter and center-of-mass energy are studied. In the framework of the participant-spectator model, the interacting system of nucleus-nucleus collisions at relativistic energies is divided into four parts (sources):the target spectator, target participant, projectile participant, and projectile spectator. Each source is treated by using the revised Landau model. The pseudorapidity distributions of charged particles are then described by the four-component Landau model. The results calculated by the model are compared and found to be in agreement with the experimental data of the PHOBOS and ALICE Collaborations. The distribution height is mainly determined by the effective nucleon number and the center-of-mass energy, and the distribution width is mainly determined by the revised width in the Landau model and the sources rapidity shifts.