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Double helicity asymmetry in π^0 production in polarized proton-proton collisions at √ s = 510 GeV with PHENIX mid-rapidity spectrometer
√ s = 510 GeV 종편극 양성자 충돌에서 PHENIX 중앙 신속도 검출기를 이용한 π^0 생성의 이중 스핀 비대칭성 측정

DC Field Value Language
dc.contributor.advisor최선호-
dc.contributor.author윤인석-
dc.date.accessioned2017-07-19T06:09:51Z-
dc.date.available2017-07-19T06:09:51Z-
dc.date.issued2016-02-
dc.identifier.other000000131989-
dc.identifier.urihttp://dcollection.snu.ac.kr:80/jsp/common/DcLoOrgPer.jsp?sItemId=000000131989-
dc.description학위논문(박사)--서울대학교 대학원 :자연과학대학 물리·천문학부,2016. 2. 최선호.-
dc.description.abstractPHENIX measurement of longitudinally double helicity asymmetry (A_LL) in inclusive π^0 production at mid-rapidity from p+ p collsions at √ s = 510 GeV from the 2012/2013 RHIC runs is presented. Since the EMC experiment revealed that spin constribution of quarks is surprisingly small, many experimental and theoeretical endeavers have been carried out to understand proton spin structure. The spin contribution of gluon (∆G) might explain the missing part of the proton spin and measuring ∆G is the ultimate goal of the dissertation. To measure ∆G, accessing the helicity gluon distribution (∆g(x,Q^2)) is necessary. The longitudinal polarized p+ p collsions and A_LL measurementss are bes tool for it. A_LL measurements of π^0 (A_LL^π^0) at √ s = 62.4 and 200 GeV and A_LL of jet at √ s = 200 GeV constrain ∆g(x,Q 2 ) significantly. As a result, positive polarization of gluon is discovered within sensed momemtum fraction (x) range, 0.05 ≤ x ≤ 0.2. However large uncertainty remains outside of the x region, especially lower x region. Thus expanding experimental sensitivity to lower x region is a crucial step to understand the ∆g(x,Q 2 ) and the spin structure. To access the lower x region, new measurement of A_LL^π^0 at higher √ s = 510 GeV is carried out and presented in the disseration. The new measurement covers x region, 0.01 ≤ x ≤ 0.1. The measurement is superior to the previous measurements from the point of not only the unique covered x range but also statistical precision. The sophisticated luminosity corrections are also presented in the dissertation to reduce the effects of the multiple collisions in single bunch crossing and the vertex z resolution of detectors. As a result, the world first positive asymmetry in hadron production is measured. The perturbative Quantum Chromodynamics theoretical predition which including the previous measurements is in excellent agreement with the presented A_LL^π^0. With the positive asymmetry and unique x coverage, the presented A_LL^π^0 will contribute to constrain the uncertainty∆g(x,Q 2 ) significantly.-
dc.description.tableofcontents1 Introduction 17
1.1 Proton Structure and Parton Model 17
1.1.1 Parton Distribution Function 17
1.1.2 Fragmentation Function 18
1.1.3 Factorization 18
1.1.4 Universality 19
1.1.5 Current Knowledge of Proton Structure 19
1.2 Spin Structure of Proton 21
1.2.1 Ellis-Jaffe Sum Rule 21
1.2.2 EMC Result and Spin Crisis 22
1.2.3 Jaffe-Monohar Sum Rule 23
1.2.4 Current Knowledge of Proton Spin Structure 23
1.3 Proton-Proton Scattering 25
1.4 Accessing the g(x,Q 2 ) through Longitudinally Polarized p+ p Scatterings at s = 510 GeV and A_LL of π^0 Production 27

2 RHIC 33
2.1 RHIC General 33
2.2 RHIC Spin Related Components 34
2.2.1 Optically-Pumped Polarized H^- Ion Source 34
2.2.2 Siberian Snake 34
2.2.3 RHIC Polarimeters 35
2.2.4 Spin Rotators 37
2.3 Run12 and Run13 Longitudinal p+ p Collision at s = 510 GeV 37
2.3.1 Polarization 38
2.3.2 Spin Patterns 38
3 PHENIX 43
3.1 Luminosity Detectors 43
3.1.1 Beam Beam Counters 43
3.1.2 Zero Degree Calorimeters 44
3.2 Tracking 45
3.2.1 Magnet 45
3.2.2 Drift Chambers 45
3.2.3 Pad Chambers 46
3.3 Ring-Imaging Cherenkov Detector 47
3.4 Electromagnetic Calorimeters 47
3.4.1 PbSc 47
3.4.2 PbGl 48
3.4.3 Tower-by-Tower Global Energy Calibration 49
3.4.4 Run-by-Run and Sector-by-Sector Energy Calibration 49
3.4.5 EMCal Tower-by-Tower ToF Calibration 50
3.5 Local Polarimeters 51
3.5.1 Shower Max Detectors 55
3.5.2 Beam direction Result 55
3.6 Triggers 57
3.6.1 BBC Level 1 Trigger 57
3.6.2 ZDC Level 1 Trigger 58
3.6.3 EMCal RICH Trigger 58
3.7 PHENIX Data Acquisition System and Prescale 59
3.8 Scaler Boards 59
3.8.1 GL1p Scaler 59
3.8.2 Star Scaler 60
4 Overview of the Measurement 61
4.1 Measuring the A_LL 61
4.2 Background Subtraction 62
5 Data Selection, π^0 Reconstruction and Background Reduction 65
5.1 Run QA 65
5.1.1 DAQ Condition 65
5.1.2 Spin Database 65
5.1.3 Polarization 65
5.1.4 GL1p Scaler and Star Scaler Agreement 66
5.1.5 EMCal Condition 66
5.2 Event Selection 66
5.2.1 Trigger Requirement 66
5.2.2 Vertex z Requirement 66
5.3 π^0 Reconstruction 66
5.3.1 Trigger Requirement 66
5.3.2 Photon Identification 67
5.3.3 π^0 Reconstruction 73
5.4 π^0 Final Statistics 74
6 Relative Luminosity 85
6.1 Relative Luminosity 85
6.2 A_LL^ZDC/BBC 86
6.3 Measuring A_LL^ZDC/BBC 87
6.4 Pileup Correction 89
6.4.1 Motivation and Procedure 89
6.4.2 Determining k_N and k_S 92
6.4.3 Effect of Pileup Correction on BBC and ZDC Scaler Rate 94
6.4.4 Effect of Pileup Correction on A_LL^ZDC/BBC 94
6.4.5 Vertex z Cut and Spin Pattern Separation Problem 95
6.5 Width Correction 96
6.5.1 Motivation and Procedure 96
6.5.2 Effect of Width Correction on A_LL^ZDC/BBC 98
6.5.3 Spin Pattern Separation Problem and Width Correction 98
6.5.4 Criticism on Width Correction 99
6.6 Residual Rate Correction 100
6.6.1 Motivation and Procedure 100
6.6.2 Connection to Width Correction 102
6.6.3 Effect of Residual Rate Correction on A_LL^ZDC/BBC 102
6.6.4 Spin Pattern Separation Problem and Residual Rate Correction 104
6.7 Measured A_LL^ZDC/BBC 104
6.7.1 Statistical Uncertainty 104
6.7.2 Systematic Uncertainty 105
7 A_LL Analysis 109
7.1 A_LL Calculation 109
7.1.1 Statistics Requirement for A_LL Calculation 109
7.1.2 Choice of P_T Bins 110
7.1.3 Relative Luminosity 110
7.1.4 Statistical Uncertainty of A_LL 111
7.1.5 Background Fraction Estimation 112
7.2 Systematic Uncertainties 123
7.2.1 False Asymmetry in Background due to Ghost Clusters: Low P_T 123
7.2.2 Uncertainty of Relative Luminosity 129
7.2.3 Global Scaling Uncertainty from Polarization 129
7.2.4 Uncertainty of Background Fraction Estimation 130
7.3 Bunch Shuffling 131
7.3.1 Procedure 131
7.3.2 Bunch Shuffling Results 131
7.4 Single Spin Asymmetries, A_L 132
7.5 Parallel Cross-Check 132
8 Results and Discussions 139
8.1 Combining Run12 and Run13 Results 139
8.2 Final Result and Comparison with Theoretical Curve 141
8.3 Prospect: Impacts on G 142

A Warn Map Generation 147
A.1 Determining Hot Towers 147
A.2 Determining Dead Towers 148
A.3 Determining Uncalibrated Towers 148
A.4 Neighbor Towers 148

B Parallel CrossCheck 149
B.1 Cross Check Result of A^π^0 +BG and A_LL^BG 149
B.2 Final Cross Check Result 156

Bibliography 157

국문초록 161
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dc.format.extent162-
dc.language.isoeng-
dc.publisher서울대학교 대학원-
dc.subjectproton spin, gluon, A_LL of π^0, PHENIX-
dc.subject.ddc523-
dc.titleDouble helicity asymmetry in π^0 production in polarized proton-proton collisions at √ s = 510 GeV with PHENIX mid-rapidity spectrometer-
dc.title.alternative√ s = 510 GeV 종편극 양성자 충돌에서 PHENIX 중앙 신속도 검출기를 이용한 π^0 생성의 이중 스핀 비대칭성 측정-
dc.typeThesis-
dc.typeDissertation-
dc.contributor.department자연과학대학 물리·천문학부-
dc.description.degreeDoctor-
dc.date.awarded2016-02-
dc.identifier.holdings000000000027▲000000000027▲000000131989▲-
Appears in Collections:
College of Natural Sciences (자연과학대학)Dept. of Physics and Astronomy (물리·천문학부)Physics (물리학전공)Theses (Ph.D. / Sc.D._물리학전공)
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