The Forward Preshower System and a Study of the J/ψ Trigger with the D Detector

296 Pages·2002·4.32 MB·English

by  Abid Patwa

The Forward Preshower System and a Study
of the J= Trigger with the D(cid:31) Detector
A Dissertation Presented
by
Abid M. Patwa
to
The Graduate School
in Partial Ful(cid:12)llment of the Requirements
for the Degree of
Doctor of Philosophy
in
Physics
State University of New York
at
Stony Brook
May 2002
State University of New York
at Stony Brook
The Graduate School
Abid M. Patwa
We, the dissertation committee for the above candidate for the Doctor of
Philosophy degree, hereby recommend acceptance of the dissertation.
dissertation director
Dr. Michael Rijssenbeek
Department of Physics and Astronomy
chairman of defense
Dr. Jack Smith
Department of Physics and Astronomy
committee member
Dr. Barbara Jacak
Department of Physics and Astronomy
outside member
Dr. Jonathan Kotcher
Physics Department
Brookhaven National Laboratory, USA
This dissertation is accepted by the Graduate School.
Graduate School
ii
Abstract of the Dissertation
The Forward Preshower System and a Study
of the J= Trigger with the D(cid:31) Detector
by
Abid M. Patwa
Doctor of Philosophy
in
Physics
State University of New York at Stony Brook
2002
This dissertation describes the Forward Preshower system, one
of four inner-tracking subdetectors in the D(cid:31) Detector, designed
and builtforoperationin Run II at the FermilabTevatron collider.
Thescintillator-baseddetectorhasbeenconstructedtoenhancethe
electron and photon triggering capability and o(cid:15)ine particle iden-
ti(cid:12)cationat D(cid:31) over abroad range inpseudorapidity. Adiscussion
of the design, technology, systematic assembly, and performance of
the system is presented along with a description of the relevant
physics topics the detector will address.
+ (cid:0)
A study of a J= e e trigger incorporating the Central
!
Preshower with the Central Calorimeter, Silicon Microstrip and
iii
Fiber Trackers is also presented. A description is given of the trig-
ger algorithm along with selection e(cid:14)ciencies and QCD rejection
as measured with Monte Carlo samples. A trigger e(cid:14)ciency of at
least 60%, with background rates well within the allocated trig-
ger bandwidth, can be achieved through the use of tracking and
electron cluster information from the preshower system.
iv
\Armed with giant machines and grand ambitions, physicists
spend billions in the race to discover the building blocks of matter."
- Time Magazine: \The Ultimate Quest"
April 16, 1990, Pp. 50-56.
\...Listen, buddy, if I could tell you in a minute what I did, it
wouldn’t be worth the Nobel Prize!..."
- Richard P. Feynman,
to a journalist
v
In honor of my parents:
To my mother
And in memory of my father
Contents
Acknowledgements : : : : : : : : : : : : : : : : : : : : : : : : :xxxiii
1 Introduction : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 1
2 Theoretical Overview : : : : : : : : : : : : : : : : : : : : : : : 3
2.1 The Standard Model . . . . . . . . . . . . . . . . . . . . . . . 3
2.2 Physics Signatures . . . . . . . . . . . . . . . . . . . . . . . . 8
3 Experimental Apparatus : : : : : : : : : : : : : : : : : : : : : 15
3.1 De(cid:12)nitions and Conventions . . . . . . . . . . . . . . . . . . . 15
3.1.1 Coordinate Systems . . . . . . . . . . . . . . . . . . . . 15
3.1.2 On Luminosities and Cross Sections . . . . . . . . . . . 17
3.2 The Tevatron Collider . . . . . . . . . . . . . . . . . . . . . . 20
3.3 D(cid:31) Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.3.1 Silicon Microstrip Tracker . . . . . . . . . . . . . . . . 26
3.3.2 Central Fiber Tracker . . . . . . . . . . . . . . . . . . . 29
3.3.3 Central Preshower . . . . . . . . . . . . . . . . . . . . 33
3.3.4 D(cid:31) Calorimetry . . . . . . . . . . . . . . . . . . . . . . 35
3.3.5 Calorimeter Readout . . . . . . . . . . . . . . . . . . . 41
3.3.6 Calorimeter Performance . . . . . . . . . . . . . . . . . 43
3.3.7 ICD . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
3.3.8 Muon System . . . . . . . . . . . . . . . . . . . . . . . 44
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3.4 D(cid:31) Trigger System . . . . . . . . . . . . . . . . . . . . . . . . 49
3.4.1 Level 1 Trigger . . . . . . . . . . . . . . . . . . . . . . 50
3.4.2 Level 2 Trigger . . . . . . . . . . . . . . . . . . . . . . 51
3.4.3 Level 3 Filter and DAQ System . . . . . . . . . . . . . 54
4 Physics Motivation for D(cid:31) Preshowers : : : : : : : : : : : : 57
4.1 Physics Topics . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
(cid:14)
4.1.1 (cid:13)/(cid:25) Separation . . . . . . . . . . . . . . . . . . . . . . 58
4.1.2 Low-pT Phenomena . . . . . . . . . . . . . . . . . . . . 60
4.1.3 Precision Measurements . . . . . . . . . . . . . . . . . 61
4.1.4 QCD and Electroweak Processes . . . . . . . . . . . . . 62
4.2 Case Study for Inclusion of FPS at D(cid:31) . . . . . . . . . . . . . 65
4.3 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
5 Properties of Scintillation-based Detectors : : : : : : : : : : 71
5.1 Scintillation Principles . . . . . . . . . . . . . . . . . . . . . . 71
5.1.1 WLS Fibers . . . . . . . . . . . . . . . . . . . . . . . . 74
5.2 Application: D(cid:31) Forward Preshower detector . . . . . . . . . 79
5.2.1 Preshower Scintillator and Fiber . . . . . . . . . . . . . 80
5.2.2 FPS Readout Scheme . . . . . . . . . . . . . . . . . . . 87
6 Forward Preshower Design : : : : : : : : : : : : : : : : : : : : 95
6.1 Conceptual Design . . . . . . . . . . . . . . . . . . . . . . . . 96
6.2 FPS Geometry and Technical Design . . . . . . . . . . . . . . 100
7 Forward Preshower Construction : : : : : : : : : : : : : : : : 111
7.1 Module Construction . . . . . . . . . . . . . . . . . . . . . . . 111
7.1.1 Spherical Template . . . . . . . . . . . . . . . . . . . . 112
7.1.2 Scintillator Strip Preparation . . . . . . . . . . . . . . 112
viii
7.1.3 Module Fabrication . . . . . . . . . . . . . . . . . . . . 115
7.1.4 Module Cutting . . . . . . . . . . . . . . . . . . . . . . 123
7.1.5 Strip-to-Strip Alignment Study . . . . . . . . . . . . . 125
7.2 Detector Support Structure and Assembly . . . . . . . . . . . 126
7.2.1 Detector Structure | General Principles . . . . . . . . 127
7.2.2 Assembly Hardware . . . . . . . . . . . . . . . . . . . . 131
7.2.3 FPS Inner Ring and Support Rib Structure . . . . . . 134
7.2.4 Modular Frame Box Assembly . . . . . . . . . . . . . . 139
7.2.5 Lead Absorber and Support . . . . . . . . . . . . . . . 142
7.3 Module Cabling and Certi(cid:12)cation . . . . . . . . . . . . . . . . 157
7.3.1 FPS Optical Connectors { Design and Support . . . . . 157
7.3.2 Preparation of Fiber & Connector Assemblies . . . . . 160
7.3.3 Module Cabling . . . . . . . . . . . . . . . . . . . . . . 165
7.3.4 LED Monitoring and Calibration Systems . . . . . . . 168
7.3.5 Module Certi(cid:12)cation and Integration . . . . . . . . . . 169
8 Installation and Alignment : : : : : : : : : : : : : : : : : : : : 171
8.1 Installation and Alignment I: FPS Support Hardware . . . . . 172
8.1.1 Inner Pin Surveying . . . . . . . . . . . . . . . . . . . 180
8.2 Installation and Alignment II: FPS Detector . . . . . . . . . . 183
8.2.1 Module Survey . . . . . . . . . . . . . . . . . . . . . . 187
8.3 Luminosity Monitor and ICD Mounting . . . . . . . . . . . . . 192
8.4 FPS Commissioning . . . . . . . . . . . . . . . . . . . . . . . 195
9 Physics Studies with the Preshower and D(cid:31) : : : : : : : : : 197
9.1 Motivation and Constraints . . . . . . . . . . . . . . . . . . . 198
9.2 Software and Trigger Framework . . . . . . . . . . . . . . . . 199
9.2.1 Event Generation and Processing: J= Signal . . . . . 199
ix
9.2.2 Event Generation and Processing: QCD background . 201
9.3 Level 3 Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . 203
9.3.1 Preliminary Studies: Matching and Mass Resolutions . 203
9.3.2 Event Preselection: L1 and L2 Simulation . . . . . . . 213
9.3.3 Classi(cid:12)cation of Electrons at Level 3 . . . . . . . . . . 215
9.3.4 CPS Detector E(cid:14)ciency . . . . . . . . . . . . . . . . . 232
9.3.5 J= Invariant Mass . . . . . . . . . . . . . . . . . . . . 233
9.3.6 L3 J= Trigger: Signal E(cid:14)ciency and Rates . . . . . . 236
9.3.7 Signal Improvements . . . . . . . . . . . . . . . . . . . 241
9.3.8 Study of L3 b-tagging . . . . . . . . . . . . . . . . . . 245
10 Summary and Conclusions : : : : : : : : : : : : : : : : : : : : 249
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