Experimental Study On Non-Photonic Electron Production In Proton-proton Collisions At 200 GeV

One of the main purposes of the relativistic heavy ion collision experiment is to study the new Quantum chromodynamics(QCD)matter—Quark-Gluon Plasma(QGP for short),and its physical properties.The QGP is expected to be produced under the extreme conditions of high temperature and high energy density.The experimental results from Relativistic Heavy Ion Collider(RHIC)at the Brookhaven National Laboratory(BNL)and the Large Hadron Collider at the European Nuclear Research Center(CERN),show that a new matter may be produced in relativistic heavy ion collisions.Since its operation in 2000,RHIC has found a large number of experimental evidence for existence of the QGP in high-energy heavy ion collisions,such as the phenomenon of"jet quenching",constituent quark scaling of elliptical flow,and so on.These experimental results indicate that a strongly-coupled Quark-Gluon Plasma(sQGP)could be formed in the gold-gold collisions at the RHIC energies.Because quarks and gluons have color charge,they are confined inside the hadron,which is the so-called color confinement.Experimentally,only the final state particles can be detected,and they have been affected by hot nuclear matter and cold nuclear matter effects.Therefore,they are not the best means to probe the evolution of QGP.The masses of heavy quarks(i.e.bottom quarks and charm quarks)are very large and they are about 4.2 GeV/c~2 and about 1.3 GeV/c~2 for bottom quark and charm quark,respectively.Both of their masses are much larger than the QCD scale parameter and the critical temperature of QGP,therefore heavy flavor quarks are dominantly produced in hard scattering processes at the early stage of high energy heavy ion collisions before the QGP formation.These heavy quarks will experience whole evolution of the QGP,so their kinematics will carry information about the QGP interactions.Therefore,heavy quarks are regarded to be ideal probes for studying the properties of QGP.At the same time,the cross section of the heavy quark in proton-proton collisions can be calculated by the perturbation QCD theory.The QCD theoretical calculation predicts the heavy quark will lose less energy than the light quark through gluon radiations due to the"dead cone effect".There are two different approaches to study open heavy flavor production:(1)direct open-heavy flavor hadron reconstruction in hadronic channels,(2)non-photonic electron,non-prompt D° and non-prompt J/?.Studies of interactions between heavy quarks and the QGP can provide new insights to the properties of the QGP.With the Solenoidal Tracker at RHIC(STAR for short),this thesis studies the electrons from semi-leptonic decays of open heavy flavor hadrons(called non-photonic electron in this thesis)in p+p collisions at center-of-mass energy of 200 GeV.Dedicated triggers for high transverse momentum electrons(BHT1 and BHT2)are used in this thesis for Run2015 proton-proton data to enhance the statistics.In this thesis,TPC and TOF detectors are used for charged particle tracking and identification.Combined with BEMC and BSMD detectors,electron are efficiently selected.The background of NPE are mainly from photonic-electrons,produced by gamma conversion,Dalitz decay of ?0 and ?,and they are subtracted by invariant mass reconstructed method.A preliminary PT spectrum of NPE is presented in this thesis.In addition,equivalent number of events,trigger efficiency estimation for BHT1 and BHT2 triggers from real data are introduced in this thesis.A Large Ion Collider Experiment(ALICE),at the Large-Hadron Collider(LHC)located at the European Center for Nuclear Research(CERN),is used to study strong interaction physics and its properties at extreme conditions,especially the exploring of QGP and its properties.Since the ALICE experiment was run in 2009,it has been stable in Runl and Run2,with large momentum range measurement capability and high tracking resolution.Many important physical results have been published.After 2021,the LHC will greatly increase the beam brightness,and the Pb-Pb events collision rate will reach 50 KHz.At present,ALICE'S central detector and its readout system couldn't meet this requirement.At the same time,in order to collect more experimental data,the ALICE experiment plans to upgrade its detectors and readout systems.One of the important upgrades is the replacement of the existing ALICE/ITS detector with a new seven-layer Monolithic Active Pixel Sensor(MAPS)technology based Inner Tracking System(ITS2).With the ITS2,ALICE will perform precision measurements of heavy flavor physics.Central China Normal University(CCNU)participated in the ALICE/ITS upgrade project and contribute to the assembly and test of Outer Barrel Hybrid Integrated Circuit(OBHIC).I have participated in part of the detector development and test.