Identification and analysis of charged hadrons in p+p interactions from NA61/SHINE experiment at CERN SPS energies

The phase-transition of strongly interacting matter is a very interesting phenom- ena, which still is not fully understood. Signi cant contribution to improving knowledge about properties of the onset of decon nement of strongly interact- ing matter might come from the NA61/SHINE experiment at CERN. The main goal of this xed-target experiment is to discover the critical point and study the properties of the onset of decon nement. This goal has been reached by the pre- cise measurement of the hadron production in proton-proton, proton-nucleus and nucleus-nucleus interactions in a wide range of system sizes and collision energies. The main goal of this thesis was to obtained two-dimensional spectra of positively and negatively charged pions, kaons and protons produced in p + p interactions at SPS energy range (20 ; 30 : 9 ; 40 ; 80 ; 158 GeV=c ). This studies are necessary for understanding of the onset of decon nement. For this purpose, identi cation and correction techniques dedicated for analysis were developed. This thesis consist of three main parts: description of the NA61/SHINE experi- ment and its physics program, introduction to identi cation methods, correction and error estimations techniques and discussion of the results. At the beginning detailed introduce to the physics program as well as detector system of NA61/SHINE is described. The emphasis has been placed on the de- tectors used for the identi cation of charged particles. Detailed characterization of the experimental setup and the physics motivation are presented in Chapter 1 and 2, respectively. The procedure of beam preparation and transportation is summarized in Chap- ter 3. The data preparation for the analysis is calibration and reconstruction. Description of this procedure is concluded in Chapter 4 together with the simula- tion chain of the experiment. To ensure that only inelastic p + p collisions are selected for the analysis, event selection criteria has been developed. Appropriate selections are described in Chapter 5. Technique of charged hadron identi cation base on energy loss ( dE=dx ) and time of ight measurements ( tof ) consist of few steps and nally identi cation probability for each individual hadron is calculated. It is presented in Chapter 6. Obtained results are biased by the detector e ects and contribution of the particles from weak decays. Therefore, appropriate corrections are calculated. Technique for determining these corrections is included in Chapter 7. In Chapter 8 statistical and systematic uncertainties are discussed. The nal results are presented in Chapter 9. Calculation of rapidity distributions as well as 4 multiplicities are also included. Moreover, particles multiplicities are compared with the NA49 experiment p + p results. Chapter 10 is devoted to study the energy and system size dependencies of particle production. Obtained results are an important step forward to study properties of the onset of decon ment. Comparison with world data allow better understanding of p + p interactions mechanism. Additionally, it is presented that even in p + p collisions rapid changes of the variables assign to the phase transition are observed