Calibration of the LHCb VELO detector and study of the decay mode D0->K-mu+nu_mu

  • Grant McGregor

Student thesis: Phd


The LHCb experiment, based at the Large Hadron Collider at CERN, is primarily designed to make precision measurements of the decays of heavy flavour hadrons, such as B and D mesons. This thesis is composed of two parts: the first consists of two studies of LHCb's vertex locator (VELO) and the second describes the development of methods for recording the decay D0->K-mu+nu_mu. The first VELO study involves calibration and monitoring of the gain (i.e. the detector response to input charge from particles). We propose a robust method to measure the gain response of each silicon sensor using calibration bits output by the sensors, and a method to recalibrate the gain simple enough to be followed by non-expert VELO users. This is followed by an investigation into into the prospects of using the VELO to perform particle identification using the characteristic energy deposition of each particle species (dE/dx).Finally, studies into the development of a trigger and a so-called `stripping line' for recording D0->K-mu+nu_mu decays is presented. The relatively high cross-section for charm decays in LHCb mean this decay (with a branching fraction of 3%) occurs frequently, and the challenge of a trigger is to reduce this to a rate acceptable to write to disk. Finally, based on a sample of data from July and August 2011, the measured q^2 distribution for this decay is compared to the simple single-pole theoretical model, and the pole mass is measured to bem_pole=2.35 + 0.81 - 0.35 GeV/c^2.
Date of Award31 Dec 2011
Original languageEnglish
Awarding Institution
  • The University of Manchester
SupervisorGeorge Lafferty (Supervisor)


  • Semileptonic
  • Charm
  • VELO
  • LHCb
  • Vertex detector

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