Energy dependence of negatively charged pion production in nucleus-nucleus collisions

The thesis is focused on yields and spectra of primary negatively charged pions produced in strong and electromagnetic processes in inelastic $^{40}$Ar+$^{45}$Sc collisions at six beam momenta: 13A, 19A, 30A, 40A, 75A and 150A GeV/𝑐. The data was taken by the NA61/SHINE experiment at the CERN Super Proton Synchrotron (SPS) in year 2015. The data was analyzed utilizing the so-called $h$− method. The method is based on the fact that the vast majority of hadrons produced in a heavy ion collision are pions. Using this fact we can apply a correction based on Monte-Carlo generated pion spectra. The correction will be mostly geometric, but excludes also weak decays, secondary interactions and contamination of particles other than pions. The corrected spectra undergo an extrapolation procedure in order to obtain full solid angle 4𝜋 spectra. This consists of an extrapolation using exponential formula in transverse momentum and a sum of two Gaussian functions in rapidity. In order to compare obtained results with other measurements, a calculation of the number of wounded nucleons is necessary. This can’t be done experimentally and the number is obtained using different Monte-Carlo generators. This allows us to normalize the pion production to collision system size. Final experimental results consist of two-dimensional transverse momentum versus rapidity and transverse mass versus rapidity spectra, one-dimensional transverse momentum, transverse mass and rapidity distributions, and finally per event negatively charged pions multiplicities. These are discussed in view of predictions for the Quark-Gluon Plasma and compared to string-hadronic models which do not have the Quark-Gluon Plasma.