000124747 001__ 124747
000124747 005__ 20190619003137.0
000124747 0247_ $$2doi$$a10.5075/epfl-thesis-4122
000124747 02470 $$2urn$$aurn:nbn:ch:bel-epfl-thesis4122-5
000124747 02471 $$2nebis$$a5573071
000124747 037__ $$aTHESIS
000124747 041__ $$aeng
000124747 088__ $$a4122
000124747 245__ $$aThe analog readout of the LHCb vertex detector and study of the measurement of the Bs oscillation frequency
000124747 269__ $$a2008
000124747 260__ $$bEPFL$$c2008$$aLausanne
000124747 300__ $$a125
000124747 336__ $$aTheses
000124747 520__ $$aThe LHCb detector is one of the four experimental setups built to detect high-energy proton collisions to be produced by the Large Hadron Collider (LHC). Located at CERN (Geneva, Switzerland), the LHC machine and the LHCb experiment are expected to start in 2008, and will then operate for several years. Being the largest collider of its kind, the LHC will open the way to new investigations, in the very-high energies, but also in terms of statistics for the study of rare-phenomena and flavor physics. In this framework LHCb is dedicated to precise measurements of CP-violating and rare decays of beauty hadrons, in order to test (or over-constrain) the Standard Model of particle physics. From the hardware point of view, the construction of such detectors represents several challenges; one of them is the routing at a very high frequency of many signals in a harsh radiation environment. We designed to this purpose a hardware setup and a software filter which together reduce the cross-talk present in the readout of the LHCb vertex detector to a level of (1 ± 2)%, leading to an improved signal quality in the acquisition chain. From the physics point of view, many of the CP-violation measurements performed at LHCb using Bs decays, for example using Bs → Ds∓ K± decays, will require as input the Bs–Bs oscillation frequency Δms. Thus the measurement of Bs–Bs oscillations, which are best observed using the flavor-specific Bs → Ds- π+ decays, will play an important role. We have developed a complete selection of Bs → Ds- π+ and Bs → Ds∓ K± events, based on Monte Carlo simulations. Assuming 2 fb-1 of data, we expect a Bs → Ds- π+ signal yield, after the first level of trigger, of 155 k events over a background between 0.6 k and 7.8 k events at 90% confidence level. Moreover, we assess with fast Monte Carlo studies the corresponding statistical sensitivity on the Bs oscillation frequency, σ(Δms) = 0.008 ps-1, on the wrong tag fraction, σ(ω) = 0.003, as well as on other parameters related to the Bs-meson system. We also addressed an important aspect of the systematics associated with the Δms measurement, and developed a method to calibrate and assess the length scale. This calibration is performed through the reconstruction of secondary interactions occurring in the material of the vertex detector. We show that the statistical relative precision of this approach quickly matches 6 × 10-5, obtained from the survey measurements of the detector.
000124747 6531_ $$aCERN
000124747 6531_ $$aLHC
000124747 6531_ $$aLHCb
000124747 6531_ $$aStandard Model
000124747 6531_ $$aCP violation
000124747 6531_ $$aBs–Bs oscillations
000124747 6531_ $$aFIR
000124747 6531_ $$aCross-talk
000124747 6531_ $$aSecondary interactions
000124747 6531_ $$alength calibration
000124747 6531_ $$aCERN
000124747 6531_ $$aLHC
000124747 6531_ $$aLHCb
000124747 6531_ $$aModèle Standard
000124747 6531_ $$aviolation de CP
000124747 6531_ $$aoscillations des mésons Bs
000124747 6531_ $$aFIR
000124747 6531_ $$acouplage diaphonique
000124747 6531_ $$ainteractions secondaires
000124747 6531_ $$acalibration des longueurs
000124747 700__ $$aBorel, Jérémie
000124747 720_2 $$aSchneider, Olivier$$edir.$$g162579$$0244630
000124747 8564_ $$uhttps://infoscience.epfl.ch/record/124747/files/EPFL_TH4122.pdf$$zTexte intégral / Full text$$s3868959$$yTexte intégral / Full text
000124747 909C0 $$0252318$$pLPHE
000124747 909CO $$pthesis-bn2018$$qDOI2$$pthesis-public$$pDOI$$pSB$$ooai:infoscience.tind.io:124747$$qGLOBAL_SET$$pthesis
000124747 918__ $$dEDPY$$cIPEP$$aSB
000124747 919__ $$aLPHE1
000124747 920__ $$b2008
000124747 970__ $$a4122/THESES
000124747 973__ $$sPUBLISHED$$aEPFL
000124747 980__ $$aTHESIS