Luminosity Measurement at the Compact Muon Solenoid Experiment of the LHC
Luminosity Measurement at the Compact Muon Solenoid Experiment of the LHC

Author: Olena Karacheban

Publisher: Springer

Published: 2018-06-22

Total Pages: 153

ISBN-13: 3319931393

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This book describes the application of a novel technology for beam instrumentation and luminosity measurement and first results on a cutting edge technology potentially to be used after the upgrade of the Large Hadron Collider to higher luminosity. It presents a unique diamond-based luminometer with a detailed performance study. The online bunch-by-bunch luminosity measurements provide an invaluable feedback to the Collider for beam optimisation and for the understanding of beam dynamics. The precision of the luminosity measurement is crucial for all physics analyses. This book highlights the Van der Meer method, which is used for the calibration of the luminometers of the CMS (Compact Muon Solenoid) experiment, and describes the estimate of systematic uncertainties, e.g. due to radiation damage of sensors and electronics and uncertainties of beam parameters. For the future high-luminosity upgrade of the collider, sapphire sensors are investigated in a test beam. It is demonstrated for the first time that sapphire sensors can be used as single particle detectors. A model for the charge transport in sapphire is developed and successfully applied.

Correction to Luminosity Measurement for the Pixel Luminosity Telescope at CMS
Correction to Luminosity Measurement for the Pixel Luminosity Telescope at CMS

Author: Krishna Thapa

Publisher:

Published: 2016

Total Pages: 86

ISBN-13:

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The search for and detailed study of new particles and forces with the Compact Muon Solenoid (CMS) detector at the Large Hadron Collider (LHC) of CERN is fundamentally dependent on the precise measurement of the rate at which proton-proton collisions produce any particles, the so-called luminosity. Therefore, a new detector, the Pixel Luminosity Telescope (PLT), dedicated to measure the luminosity at high precision was added to the CMS experiment in 2015. It measures the inclusive charged particle production from each collision of proton bunches in the LHC. Additional charged particles which are observed by the instrument but produced from sources other than collisions are characterized by measurements of particle trajectories and subtracted from the luminosity. Methods were developed to calculate the corrections to the luminosity measurement of the PLT.

Inclusive b Jet Production in Proton-Proton Collisions
Inclusive b Jet Production in Proton-Proton Collisions

Author: Patrick L.S. Connor

Publisher: Springer Nature

Published: 2019-11-29

Total Pages: 325

ISBN-13: 3030343839

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^ 74 GeV and |y| 2.4; the b jets must contain a B hadron. The measurement has significant statistics up to p T ∼ O(TeV). Advanced methods of unfolding are performed to extract the signal. It is found that fixed-order calculations with underlying event describe the measurement well.

Research and Development Studies for CMS at the Super LHC Conditions and Inclusive Search for New Physics at CMD with Jets and Missing Momentum Signature
Research and Development Studies for CMS at the Super LHC Conditions and Inclusive Search for New Physics at CMD with Jets and Missing Momentum Signature

Author: Elif Asli Albayrak

Publisher:

Published: 2011

Total Pages: 135

ISBN-13:

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This thesis is composed of two independent parts. The first part is devoted to hadronic endcap calorimeter R & D studies for the Large Hadron Collider (LHC) higher luminosity conditions, whereas in the second part a search for new physics at the Compact Muon Solenoid (CMS) experiment is presented. After a brief introduction to the LHC and the CMS experiment, in the first part R & D studies on the active material of hadronic endcap (HE) calorimeter for compact muon solenoid detector upgrade are presented. We performed radiation damage and beam test studies on several wavelength shifter materials, and found that the p-terphenyl deposited quartz plates give improved light efficiency and they are also radiation hard. As a result we propose to substitute the current HE scintillator tiles with p-terphenyl deposited quartz plates for the higher luminosity era of the Large Hadron Collider. In the second part, an inclusive search for new physics with the jets and missing momentum signature at the Large Hadron Collider is presented for 36pb-1 data collected by the compact muon solenoid detector from March 2010 to November 2010. The emphasis was put on jet resolution measurements for the QCD background estimation with a photon-jet data sample. We did not observe an excess above the background, and thus derived upper limits in the context of R-parity conserving Constrained Minimal Supersymmetric Standard Model (CMSSM) and, more generally in the simplified model spectra. In CMSSM, depending on squark and gluino masses a 95% confidence level (CL) upper limit for cross section of 2-3 pb is obtained, and gluino masses below 500 GeV are excluded with 95% CL for squarks with mass below 1 TeV. In simplified models, depending on the decay chain and mass of the new particles which are pair-produced and decay to to either one or two jets and a dark matter candidate, a 95% CL upper limit on the production cross section in the 0.5-30 pb range is obtained.

At the Leading Edge
At the Leading Edge

Author: Dan Green

Publisher: World Scientific

Published: 2010

Total Pages: 445

ISBN-13: 9814304670

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Too often descriptions of detectors focus on the ?what? and not the ?why?. This volume aims to elucidate how the requirements of the physics at the Large Hadron Collider (LHC) define the detector environment. In turn, the detector choices are made to adopt to that environment. The goal of LHC physics is to explore the mechanism for electroweak symmetry breaking. Because of the minuscule cross-sections which need to be explored, 0.1 fb, the LHC needs to provide 100 fb-1/yr, or an instantaneous luminosity of 1034 / (cm2 sec). With a bunch crossing interval of 25 nsec, well matched to detector speeds, there will be 25 events occupying each bunch crossing. Thus the physics requires fast, finely segmented, low noise and radiation resistant detectors which provide redundant measurements of the rarely produced electrons and muons. To achieve those goals, new ground was broken in constructing the A Toroidal LHC ApparatuS (ATLAS) and Compact Muon Solenoid (CMS) detectors in the vertex detectors, tracking systems, calorimetry, strong magnets, muon systems, front end electronics, trigger systems, and in the data acquisition methods used.

CMS Pixel Detector Upgrade and Top Quark Pole Mass Determination
CMS Pixel Detector Upgrade and Top Quark Pole Mass Determination

Author: Simon Spannagel

Publisher: Springer

Published: 2017-08-01

Total Pages: 286

ISBN-13: 331958880X

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This thesis addresses two different topics, both vital for implementing modern high-energy physics experiments: detector development and data analysis. Providing a concise introduction to both the standard model of particle physics and the basic principles of semiconductor tracking detectors, it presents the first measurement of the top quark pole mass from the differential cross-section of tt+J events in the dileptonic tt decay channel. The first part focuses on the development and characterization of silicon pixel detectors. To account for the expected increase in luminosity of the Large Hadron Collider (LHC), the pixel detector of the compact muon solenoid (CMS) experiment is replaced by an upgraded detector with new front-end electronics. It presents comprehensive test beam studies conducted to verify the design and quantify the performance of the new front-end in terms of tracking efficiency and spatial resolution. Furthermore, it proposes a new cluster interpolation method, which utilizes the third central moment of the cluster charge distribution to improve the position resolution. The second part of the thesis introduces an alternative measurement of the top quark mass from the normalized differential production cross-sections of dileptonic top quark pair events with an additional jet. The energy measurement is 8TeV. Using theoretical predictions at next-to-leading order in perturbative Quantum Chromodynamics (QCD), the top quark pole mass is determined using a template fit method.

Elementary Particle Interactions with CMS at LHC.
Elementary Particle Interactions with CMS at LHC.

Author:

Publisher:

Published: 2016

Total Pages: 10

ISBN-13:

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The High Energy Particle Physics group of the University of Tennessee participates in the search for new particles and forces in proton-proton collisions at the LHC with the Compact Muon Solenoid experiment. Since the discovery of the Higgs boson in 2012, the search has intensified to find new generations of particles beyond the standard model using the higher collision energies and ever increasing luminosity either directly or via deviations from standard model predictions such as the Higgs boson decays. As part of this effort, the UTK group has expanded the search for new particles in four-muon final states, and in final states with jets, has successfully helped and continues to help to implement and operate an instrument for improved measurements of the luminosity needed for all data analyses, and has continued to conduct research of new technologies for charged particle tracking at a high-luminosity LHC.

Study of Double Parton Scattering in Photon + 3 Jets Final State
Study of Double Parton Scattering in Photon + 3 Jets Final State

Author: You-Hao Chang

Publisher: Springer

Published: 2017-01-20

Total Pages: 107

ISBN-13: 9811038244

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This book mainly focuses on the study of photon + 3 jets final state in Proton-Proton Collisions at √s = 7TeV, searching for patterns of two (or more) distinct hard scatterings in the same collision, i.e the so-called Double Parton Scattering (DPS). A new method by using Monte Carlo generators was performed and provides higher order corrections to the description of the Single Parton Scattering (SPS) background. Further it is investigated whether additional contributions from DPS can improve the agreement between the measured data and the Monte Carlo predictions. The current theoretical uncertainties related to the SPS background are found to be larger than expectation. At the same time a rich set of DPS-sensitive measurements is reported for possible further interpretation.

Associated Production of W + Charm in 13 TeV Proton-Proton Collisions Measured with CMS and Determination of the Strange Quark Content of the Proton
Associated Production of W + Charm in 13 TeV Proton-Proton Collisions Measured with CMS and Determination of the Strange Quark Content of the Proton

Author: Svenja Karen Pflitsch

Publisher: Springer Nature

Published: 2020-08-18

Total Pages: 148

ISBN-13: 303052762X

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The associated production of a W boson and a single charm quark (W+c) is the only process in proton-proton collisions that directly probes the strange quark content of the proton. In this thesis, W+charm production is measured in proton-proton collisions at the LHC at 13 TeV, as recorded by the Compact Muon Solenoid (CMS) experiment. The analysis focuses on the identification of W bosons in their leptonic decay to a muon and a neutrino and charm quarks are tagged via the full reconstruction of D*-Mesons. The measured cross sections of W+c production are used, in combination with other relevant CMS results and the most precise HERA DIS data, in a QCD analysis to determine the strange quark content of the proton. The resulting strange quark distribution and suppression, with respect to the other light sea quarks, are in good agreement with those obtained in neutrino scattering experiments and extend their kinematic reach.