Document Type

Dissertation

Date of Degree

Spring 2016

Degree Name

PhD (Doctor of Philosophy)

Degree In

Physics

First Advisor

Jane M. Nachtman

Abstract

A measured cross section of simultaneously produced Υ 1S and �/� mesons is performed using 20 fb-1 integrated luminosity in proton-proton collisions at √� = 8 TeV center of mass energy recorded by the CMS detector. Both mesons are fully reconstructed from their final states, �+- . To extract the signal yield, an extended maximum likelihood fit is used on two ( invariant mass of Υ(1S) and J/ψ ) and three (invariant mass of Υ(1S) and J/ψ, cτ) dimensional components. A two-dimensional extended likelihood fit is used for the signal yield of data and a three-dimensional extended likelihood fit is used to know the possibility of displaced �/� candidate events arising from a B meson decay. A data embedding method is used to correct the efficiency in the data. The cross section in the fiducial region, defined as � < 2.0, is determined to be 16.5±3.6(����) ± 2.6(����) ��. The Silicon Pixel detector plays an important role in identifying secondary vertices and tagging long-lived particles such as b-quarks [1]. Because the silicon pixel detector is close to the interaction point of the CMS detector, it is exposed to a very harsh radiation environment. The silicon sensors of the pixel detector need to be replaced from time to time because of radiation damage. The CMS Phase I upgrade aims to have a sensor design that has a similar or better radiation performance compared with the original construction. To check the quality of wafers to be used in the CMS detector, Sintef did IV (current & voltage) measurements on all sensors of the production wafers and CV (capacitance & voltage) measurement on one diode of each wafer. When we receive production wafers from Sintef, we re-measure a small percentage of the wafers.

Our IV results are very close to Sintef results, with only a 4% disagreement. CV measurements confirm the ~65 V full depletion voltage from the Sintef measurements. In order to improve the physics measurements capabilities for the harsh radiation environments at Large Hadron Collider (LHC), radiation hard detectors are needed. Secondary Emission Method (SEM) is a technique to measure the energy of particles such as e, n, and p in extreme radiation environments. Secondary Emission Ionization Calorimetry is a new technique for high radiation conditions. We designed two different types of test boards to test Hamamatsu single anode R7761 and multi-anode R5900-00-M16 PMTs and compared average gain values for both SE and PMT modes. We found that both values (SE and PMT) were comparable, which means the test boards that were developed perform very well and they could be used at Fermilab Test Beam Facility or in the CERN H2 beam area for the detection of minimum ionizing and showering particles.

Public Abstract

A measured cross section of simultaneously produced Υ(1S) and �/� mesons is performed using 20 fb-1 integrated luminosity in proton-proton collisions at √� = 8 TeV center of mass energy recorded by the CMS detector. Both mesons are fully reconstructed from their final states, �+-. To extract the signal yield, an extended maximum likelihood fit is used on two ( invariant mass of Υ(1S) and J/ψ ) dimensional components. The cross section in the fiducial region, defined as � < 2.0, is determined to be 16.5±3.6(����) ± 2.6(����) ��. The silicon pixel detector is close to the interaction point of the CMS detector, so it is exposed to a very harsh radiation environment. The silicon sensors of the pixel detector need to be replaced from time to time because of radiation damage. For the next interaction, a silicon sensor must resist an integrated luminosity of 300 fb-1. The silicon wafers that were made by Sintef were tested to check the capability of the sensors to be used for Phase I upgrade. Due to increasing integrated luminosity at particle accelerators, radiation hard detectors are needed. Secondary Emission Ionization Calorimetry is a new technique for high radiation conditions. The purpose is to design an SE module from a conventional PMT mode for secondary emission ionization calorimetry.

Keywords

publicabstract, CMS, Jpsi, Pixel, SE, Upgrade, Upsilon

Pages

xiv, 129 pages

Bibliography

Includes bibliographical references (pages 125-129).

Copyright

Copyright 2016 Kamuran Dilsiz

Included in

Physics Commons

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