편극 양성자 충돌에서 PHENIX 뮤온 검출기를 이용한 W 보존 생성의 단일 스핀 비대칭도 측정

학위논문(박사)--서울대학교 대학원 :자연과학대학 물리·천문학부,2015. 2. Kiyoshi Tanida.Measurement of parity violating single spin asymmetry of W boson production in polarized p+p collisions provides clean access to the polarized antiquark parton distribution functions (PDF) in order to understand the spin structure of the proton. The asymmetry for W±/Z \rightarrow \mu^{±} has been measured using longitudinally polarized proton proton collisions at ps = 510 GeV at RHIC using the PHENIX muon spectrometer. The PHENIX muon detector measures muons from W/Z decays, and it covers pseudorapidity region of 1.2 <\eta< 2.4. The data analyzed in this thesis was collected in 2012 with total integrated luminosity of 53 pb^{−1}. The resulting asymmetries are: A^{\mu^{-}}_{L} = 0.706 +0.439 −0.345 (stat.) +0.294 −0.450(syst.), = 1.75 (68% C.L) A^{\mu^{-}}_{L} = −0.130 +0.338 −0.359 (stat.) +0.421 −0.566(syst.), = −1.75 (68% C.L) A^{\mu^{+}}_{L} = 0.079 +0.203 −0.200 (stat.) +0.209 −0.226(syst.), = 1.71 (68% C.L) A^{\mu^{+}}_{L} = 0.122 +0.200 −0.199 (stat.) +0.218 −0.178(syst.), = −1.71 (68% C.L) and they are consistent with the theoretical predictions from the next-leading-order global analyses within 1 sigma uncertainty, except for the asymmetry for \mu^{+} which is 1.5 sigma away to the upper direction. This results will improve the constraints on the light antiquark PDFs in the future global analysis.1 Introduction 1 1.1 Proton Structure . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1.1 Parton Model . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1.2 Parton Distribution Function . . . . . . . . . . . . . . . 6 1.1.3 Quantum Chromodynamics . . . . . . . . . . . . . . . . 7 1.1.4 Unpolarized PDF . . . . . . . . . . . . . . . . . . . . . . 8 1.1.5 Spin Structure of the Proton . . . . . . . . . . . . . . . 9 1.1.6 Polarized PDF . . . . . . . . . . . . . . . . . . . . . . . 12 1.2 Studying the Antiquark Polarized PDF through p-p Scattering 16 1.2.1 W Boson Production in p-p Collisions . . . . . . . . . . 16 1.2.2 Single Spin Asymmetry . . . . . . . . . . . . . . . . . . 18 1.2.3 Outline of this thesis . . . . . . . . . . . . . . . . . . . . 20 2 RHIC 22 2.1 Polarized Proton Source . . . . . . . . . . . . . . . . . . . . . . 22 2.2 Accelerator complex . . . . . . . . . . . . . . . . . . . . . . . . 23 2.3 Siberian Snake . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 2.4 Spin Rotator . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 2.5 Polarimeters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 2.6 RHIC Performance Summary . . . . . . . . . . . . . . . . . . . 29 3 PHENIX 31 3.1 Global Detectors . . . . . . . . . . . . . . . . . . . . . . . . . . 32 3.1.1 Beam Beam Counters . . . . . . . . . . . . . . . . . . . 32 3.1.2 Zero Degree Calorimeters . . . . . . . . . . . . . . . . . 34 3.2 Muon Magnets . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 3.3 Muon Spectrometer . . . . . . . . . . . . . . . . . . . . . . . . 37 3.3.1 Muon Tracking Chambers . . . . . . . . . . . . . . . . . 37 3.3.2 Muon Identifier . . . . . . . . . . . . . . . . . . . . . . . 38 3.3.3 Forward Muon Arm Upgrade . . . . . . . . . . . . . . . 40 3.3.4 Hadron Absorber . . . . . . . . . . . . . . . . . . . . . . 41 3.3.5 MuTRG-FEE . . . . . . . . . . . . . . . . . . . . . . . . 41 3.3.6 Resistive Plate Chambers . . . . . . . . . . . . . . . . . 44 3.3.7 Forward Silicon Vertex Detectors . . . . . . . . . . . . . 46 3.4 Tracking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 3.5 Triggering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 4 Analysis 54 4.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 4.2 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 4.2.1 Integrated Luminosity . . . . . . . . . . . . . . . . . . . 57 4.2.2 Relative Luminosity . . . . . . . . . . . . . . . . . . . . 59 4.2.3 Detector Configuration . . . . . . . . . . . . . . . . . . . 59 4.2.4 Quality Assurance . . . . . . . . . . . . . . . . . . . . . 60 4.3 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 4.4 Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 4.5 Event Cut . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 4.6 Signal Pre-selection . . . . . . . . . . . . . . . . . . . . . . . . . 71 4.7 Performance of the Muon Spectrometer . . . . . . . . . . . . . 76 4.7.1 MuID Hit Efficiency . . . . . . . . . . . . . . . . . . . . 76 4.7.2 MuTr momentum smearing . . . . . . . . . . . . . . . . 79 4.7.3 MuTr Hit Efficiency . . . . . . . . . . . . . . . . . . . . 80 4.7.4 Trigger Efficiency . . . . . . . . . . . . . . . . . . . . . . 84 4.8 Background Estimation . . . . . . . . . . . . . . . . . . . . . . 92 4.8.1 Compsition of Probability Density Functions . . . . . . 93 4.8.2 Muonic Background Estimation . . . . . . . . . . . . . . 98 4.8.3 Extended Unbinned Maximum Likelihood Fit . . . . . . 102 4.8.4 Result . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 4.8.5 Cross check . . . . . . . . . . . . . . . . . . . . . . . . . 104 4.9 Single Spin Asymmetry Measurement . . . . . . . . . . . . . . 107 4.9.1 Single Spin Asymmetry . . . . . . . . . . . . . . . . . . 107 4.9.2 Systematic Uncertainty . . . . . . . . . . . . . . . . . . 110 5 Discussion and Conclusion 115 5.1 Single spin asymmetry result . . . . . . . . . . . . . . . . . . . 115 5.2 Future Prospects . . . . . . . . . . . . . . . . . . . . . . . . . . 117 A Local Polarimetry 119 B Quality Assurance 121Docto

Tunable Two-Channel Magnetotransport in SrRuO3 Ultrathin Films Achieved by Controlling the Kinetics of Heterostructure Deposition

In the field of oxide heterostructure engineering, there are extensive efforts to couple the various functionalities of each material. The Berry curvature-driven magnetotransport of SrRuO3 ultrathin films is currently receiving a great deal of attention because it is extremely sensitive to the electronic structures near the Fermi surface driven by extensive physical parameters such as spin?orbit coupling and inversion symmetry breaking. Although this is beneficial in terms of heterostructure engineering, it renders transport behavior vulnerable to nanoscale inhomogeneity, resulting in artifacts called “hump anomalies.”Here, a method to tune the magnetotransport properties of SrRuO3 ultrathin films capped by LaAlO3 layers is developed. The kinetic process of pulsed laser deposition by varying the growth pressure during LaAlO3 layer deposition is systematically controlled. Furthermore, the effects of nanoscale inhomogeneity on the Berry curvature near the Fermi surface in SrRuO3 films are investigated. It is found that the high kinetic energy of the capping layer adatoms induces stoichiometric modification and nanoscale lattice deformation of the underlying SrRuO3 layer. The control of kinetics provides a way to modulate magnetization and the associated magnetotransport of the SrRuO3 layer