Multi-source Mechanism Of Final-state Particle Production In High Energy Collisions

High energy heavy ion collision is an important subject in particle and nuclear physics. In a very early stage of the collision, the energy density is expected to be sufficient to dissolve normal nuclear matter into a phase of quark matter, which exists for only a short time, and then the fireball colls down and hadronizes into hadrons. The quark matter at high temperature and high density is only created for the briefest of instants, so we cannot observe it directly in the existing laboratory conditions. However, we can extract a judgment of the creation of the quark matter by measuring and analyzing the spectra of identified particles produced after thermal freeze-out in heavy ion collision. Therefore, high energy heavy ion collisions provide a unique opportunity for the study of the quark matter. Experimentally, accelerators provide support for the high energy heavy ion collision. Recently, the relativistic heavy ion collider (RHIC) and the large hadron collider (LHC) play an especially important role. With the development of the experiment, theoretical workers have proposed various models to explain these experimental results. In order to describe final-state particle distributions, a multisource thermal model was proposed and developed. The model based on the multisource production successfully describes the particle distributions.This thesis analyzes the angular distributions and transverse momentum spectra of final-state particles in the framework of the multisource thermal model. Firstly, the polar angle distributions of φmeson produced in the neutral decay mode in the reaction yp â†'pφ(KsKL) are discussed in the framework of the multisource thermal model. We analyze the expansions and movements of the emission sources in the transverse momentum space. In the calculation, we use the thermal and statistical method. Comparing with the experimental data, it is seen that modeling results can describe the data. The results show the anisotropy of the angular distributions of φ meson is caused by the expansions and movements of the emission sources. Moreover, it is found that the movement factor increases linearly with the photon beam energies. Secondly, proton and charged pion transverse momentum spectra of p+Cu and p+Pb reactions at 3,8, and 15 GeV/c are investigated in the framework of the multisource thermal model. We split the sources into many groups in accordance with kinetic laws and geometrical positions. For each source in the groups, its share of the transverse momentum spectrum of the final-state particles obeys an exponential function. Considering the contributions of many sources, particle distribution obeys an Erlang distribution. We use the Erlang distribution to explain the transverse momentum spectra. And the result shows the Erlang distribution can describe the data of HARP-CDP. It is found that the widths of the particle distributions in both p+Cu and p+Pb collisions decrease with increasing the angle for the same incident momentum.