Monte Carlo technique and applications in high energy physics simulations

in this thesis, FCNC (Flavour Changing Neutral Channel) decay simulation of fourthStandard Model (SM) quarks family was studied for LHC, ATLAS experiment at CERN. inthis study, PYTHIA Monte Carlo event generator and ATLFAST fast detector simulationprogram for ATLAS detector were used.Throughout study, observation of signals of fourth SM kuarks family which are u4 andd4 with 320 GeV mass, were investigated for pp^>uJlA, u4 -^ bW+ ,M4 -^ gt(Zt) andpp^-d4d4, d4 -^>tW~ -^>bW+W~ decay channels and the decay cross-sections wereobtained as 1.158 xlCr 1 0 mb. Hence, products are given in analysis table obtained bysimulation, fırst decay products and characteristics of this products, next uA signal was obtainedby combining this products. The lowest required luminosity to observe UA signal between 300-800 GeV is 3 x l ( T 3 1 cm~2s~\Keywords: ATLAS experiment, Democratic Mass Matrix (DMM), Flavour democracy, FourthSM family, LHC.