This thesis presents several studies of data collected at the LHCb detector during its first two years of operation. A detector upgrade study is first presented, using simulated events at an increased luminosity. A second study involves radiation damage to the silicon sensors of the LHCb Vertex Locator. During 2010 and 2011the silicon sensors were exposed to a range of fluences, with sensors in the mostactive regions exposed to fluences of up to approximately 45x10^12 1MeV neutron equivalent (1MeV neq). The first observation of n+-on-n sensor type inversion at the Large Hadron Collider is reported, occurring at a fluence of around (10-15)x10^12 of 1MeV neq. The effective depletion voltages of the only n+-on-p sensors in use at the Large Hadron Collider have also been studied, with decreases of around 25V observed after initial irradiation. Following this, the effective depletion voltage inn+-on-p type sensors is observed to increase at a comparable rate to type inverted n+-on-n type sensors. A reduction in the charge collection efficiency due to an unexpected effect involving the sensor readout lines is also observed. A third study relates to CP violation in neutral B-meson mixing, by the measurement of the flavour-specific asymmetry. In the Standard Model, CP violation from this source is expected to be of order 10^-4. Any measured enhancement of this would be a strong indication of new physics. The DØ collaboration has measured the flavour specific asymmetry from B0 and B0s mixing, and found it to be inconsistent with the Standard Model at a confidence level of 3.9 standard deviations, thus motivating an independent measurement from the LHCb experiment. Using the full 2011 LHCb dataset, corresponding to 1.0 fb^-1 of recorded luminosity, the B0s-meson component of the flavour-specific asymmetry is measured to be afs_s = (-0.12 +/- 0.48 +/- 0.34)%, where the first uncertainty is statistical and the second is systematic. This is the single most accurate measurement of afs_s, and is consistent with both the DØ measurement and the Standard Model prediction.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:574298 |
| Date | January 2013 |
| Creators | Webber, Adam Dane |
| Contributors | Lafferty, George |
| Publisher | University of Manchester |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | https://www.research.manchester.ac.uk/portal/en/theses/radiation-damage-studies-in-the-lhcb-velo-detector-and-measurement-of-the-flavourspecific-asymmetry-in-semileptonic-bdecays(6a41db51-8d4e-4b43-914b-80a1c73d5271).html |
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