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The charged particle multiplicity at center of mass energies from 900 GeV to 7 TeV measured with the ATLAS experiment at the Large Hadron Collider

Citation

Gray, Heather M. (2011) The charged particle multiplicity at center of mass energies from 900 GeV to 7 TeV measured with the ATLAS experiment at the Large Hadron Collider. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechTHESIS:11242010-093045913

Abstract

The first measurements made by the ATLAS experiment at the LHC are presented. The charged particle multiplicity, its dependence on transverse momentum and pseudorapidity, and the relationship between mean transverse momentum and pseudorapidity are measured for events with at least one charged particle in the kinematic range |eta| < 2.5 and pT > 500 MeV. The charged particle multiplicity distributions are measured at the three centre of mass energies at which protons have been collided in the LHC: 900 GeV, 2.36 TeV and 7 TeV. The results are compared to predictions from Monte Carlo models of proton-proton collisions. All models predicted a multiplicity at least 10\% lower than was measured. They also failed to predict a sufficient increase in the multiplicity when the centre of mass energy increased from 900 GeV to 7 TeV. Updated models have already been produced using these data, which provide a significantly better description of the properties of proton-proton collisions at LHC energies.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:lhc atlas minbias
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Physics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Hughes, Emlyn Willard
Thesis Committee:
  • Tombrello, Thomas A. (chair)
  • Wise, Mark B.
  • Spiropulu, Maria
  • Hughes, Emlyn Willard
Defense Date:9 November 2010
Record Number:CaltechTHESIS:11242010-093045913
Persistent URL:http://resolver.caltech.edu/CaltechTHESIS:11242010-093045913
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:6189
Collection:CaltechTHESIS
Deposited By: Heather Gray
Deposited On:07 Dec 2010 16:46
Last Modified:26 Dec 2012 04:32

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