Table Of Content+
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
