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CMS HF Calorimeter PMTS [thesis] PDF

179 Pages·2003·5.086 MB·English
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+ CMS HF CALORIMETER PMTS AND Ξ LIFETIME MEASUREMENT C by Ugur Akgun An Abstract Of a thesis submitted in partial fulfillment of the requirements for the Doctor of Philosophy degree in Physics in the Graduate College of The University of Iowa December 2003 Thesis Supervisor: Professor Yasar Onel 1 ABSTRACT This thesis consists of two parts: In the first part we describe the Photomul- tiplier Tube (PMT) selection and testing processes for the Hadronic Forward (HF) calorimeter of the CMS, a Large Hadron Collier (LHC) experiment at CERN. We report the evaluation process of the candidate PMTs from three different manu- facturers, the complete tests performed on the 2300 Hamamatsu PMTs which will be used in the HF calorimeter, and the details of the PMT Test Station that is in University of Iowa CMS Laboratories. In the second part we report the Ξ+ lifetime c measurement from SELEX, the charm hadro-production experiment at Fermilab. Based upon 301±31 events from three different decay channels, by using the binned maximum likelihood technique, we observe the lifetime of Ξ+ as 427±31±13 fs. c Abstract Approved: Thesis Supervisor Title and Department Date + CMS HF CALORIMETER PMTS AND Ξ LIFETIME MEASUREMENT C by Ugur Akgun A thesis submitted in partial fulfillment of the requirements for the Doctor of Philosophy degree in Physics in the Graduate College of The University of Iowa December 2003 Thesis Supervisor: Professor Yasar Onel Copyright by UGUR AKGUN 2003 All Rights Reserved Graduate College The University of Iowa Iowa City, Iowa CERTIFICATE OF APPROVAL PH.D. THESIS This is to certify that the Ph.D. thesis of Ugur Akgun has been approved by the Examining Committee for the thesis requirement for the Doctor of Philosophy degree in Physics at the December 2003 graduation. Thesis committee: Yasar Onel, Thesis Supervisor Edward R. McCliment Robert L. Merlino Paul D. Kleiber Tuong Ton-That To my Dad and Mom, who always supported me to follow my dreams ii ACKNOWLEDGMENTS I am grateful to my advisor Prof. Yasar Onel for his support during my research on CMS and SELEX experiments. My gratitute goes to my friend and colleque Ahmet Sedat Ayan, who went through all the steps of graduate journey in the University of Iowa with me. I am also grateful to my CMS colleagues, Erhan Gulmez, Jonathan Olson, Michael Miller, Ianos Schmidt, and Peter Bruecken for their invaluable contributions to the PMT tests station that we constructed. I owe thankstomyE781collaborators, PeterCooper, MaurizioIori, SoonYun, andJames Russ for their guidance on SELEX analysis. Finally, I thank to my dearest Firdevs Duru for her constant support, encouragement, and love throughout my life outside physics. iii ABSTRACT This thesis consists of two parts: In the first part we describe the Photomul- tiplier Tube (PMT) selection and testing processes for the Hadronic Forward (HF) calorimeter of the CMS, a Large Hadron Collier (LHC) experiment at CERN. We report the evaluation process of the candidate PMTs from three different manu- facturers, the complete tests performed on the 2300 Hamamatsu PMTs which will be used in the HF calorimeter, and the details of the PMT Test Station that is in University of Iowa CMS Laboratories. In the second part we report the Ξ+ lifetime c measurement from SELEX, the charm hadro-production experiment at Fermilab. Based upon 301±31 events from three different decay channels, by using the binned maximum likelihood technique, we observe the lifetime of Ξ+ as 427±31±13 fs. c iv TABLE OF CONTENTS LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii CHAPTER 1 LARGE HADRON COLLIDER AND CMS EXPERIMENT . . . . . 1 1.1 The Large Hadron Collider . . . . . . . . . . . . . . . . . . . . 1 1.1.1 The Accelerator . . . . . . . . . . . . . . . . . . . . . . 1 1.1.2 LHC Physics . . . . . . . . . . . . . . . . . . . . . . . . 6 1.2 CMS Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 1.2.1 Magnet . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 1.2.2 Muon System . . . . . . . . . . . . . . . . . . . . . . . 13 1.2.3 Tracking . . . . . . . . . . . . . . . . . . . . . . . . . . 15 1.2.4 The Electromagnetic Calorimeter (ECAL) . . . . . . . . 16 1.2.5 The Hadronic Calorimeter (HCAL) . . . . . . . . . . . 17 1.2.6 The Hadronic Forward (HF) Calorimeter . . . . . . . . 18 2 PHOTOMULTIPLIERTUBE(PMT)EVALUATIONFORTHECMS HF CALORIMETER . . . . . . . . . . . . . . . . . . . . . . . . . . 22 2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 2.2 HF Requirements for PMTs . . . . . . . . . . . . . . . . . . . . 23 2.3 Evaluation Procedure . . . . . . . . . . . . . . . . . . . . . . . 23 2.3.1 Timing Measurements . . . . . . . . . . . . . . . . . . . 25 2.3.2 Dark Current . . . . . . . . . . . . . . . . . . . . . . . . 29 2.3.3 Current Gain . . . . . . . . . . . . . . . . . . . . . . . . 30 2.3.4 Single Photoelectron Spectrum . . . . . . . . . . . . . . 32 2.3.5 Linearity Studies . . . . . . . . . . . . . . . . . . . . . . 43 2.3.6 X-Y Variation of Photocathode . . . . . . . . . . . . . . 51 3 COMPLETE TESTS OF THE HF CALORIMETER PMTS . . . . 52 3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 3.2 The University of Iowa PMT Test Station . . . . . . . . . . . . 53 3.3 PMT Tests and Results . . . . . . . . . . . . . . . . . . . . . . 57 3.3.1 Timing Characteristics . . . . . . . . . . . . . . . . . . 57 3.3.2 Single Pulse Linearity . . . . . . . . . . . . . . . . . . . 63 3.3.3 Dark Current and Relative Gain . . . . . . . . . . . . . 66 3.3.4 Sampling Tests . . . . . . . . . . . . . . . . . . . . . . . 69 4 SELEX (E781) EXPERIMENT . . . . . . . . . . . . . . . . . . . . 83 4.1 SELEX Physics Reach . . . . . . . . . . . . . . . . . . . . . . . 83 4.1.1 Charm Physics Program . . . . . . . . . . . . . . . . . . 83 4.1.2 Non-Charm Physics Program . . . . . . . . . . . . . . . 85 4.2 SELEX Apparatus . . . . . . . . . . . . . . . . . . . . . . . . . 86 4.2.1 Detector Overview . . . . . . . . . . . . . . . . . . . . . 86 4.2.2 SELEX Coordinate System and Spectrometers . . . . . 87 4.2.3 Analyzing Magnets . . . . . . . . . . . . . . . . . . . . 87 4.2.4 Beam Spectrometer . . . . . . . . . . . . . . . . . . . . 89 4.2.5 Vertex Spectrometer . . . . . . . . . . . . . . . . . . . . 93 4.2.6 M1 Spectrometer. . . . . . . . . . . . . . . . . . . . . . 95 4.2.7 M2 Spectrometer. . . . . . . . . . . . . . . . . . . . . . 98 4.2.8 M3 Spectrometer. . . . . . . . . . . . . . . . . . . . . . 103 4.2.9 Neutron Calorimeter . . . . . . . . . . . . . . . . . . . . 103 4.2.10 Trigger and Data Acquisition System . . . . . . . . . . 104 5 Ξ+ LIFETIME ANALYSIS . . . . . . . . . . . . . . . . . . . . . . . 106 c 5.1 Charm Baryon Overview . . . . . . . . . . . . . . . . . . . . . 106 5.2 SELEX Ξ+ Data . . . . . . . . . . . . . . . . . . . . . . . . . . 110 c 5.3 Event Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 5.4 Analysis Technique . . . . . . . . . . . . . . . . . . . . . . . . 124 5.5 Systematic Errors . . . . . . . . . . . . . . . . . . . . . . . . . 134 6 CONCLUSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140 APPENDIX A THE CUT OPTIMIZATION STUDY ON SELEX PASS2 DATA . . 142 A.1 Cut Optimization Study . . . . . . . . . . . . . . . . . . . . . . 143 REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154 vi

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