The lifetime of the tau lepton is measured using data collected in 1994 by the L3 detector at LEP. The precise track position information of the Silicon Microvertex Detector is exploited. The tau ...lepton lifetime is determined from the signed impact parameter distribution for 30 322 tau decays into one charged particle and from the decay length distribution for 3891 tau decays into three charged particles. Combining the two methods we obtain $\tau_{\tau}$ = 290.1 $\pm$ 4.0 fs.
The barrel muon chambers of the CMS detector consist of three sets of four layers of rectangular drift tubes. The performance of several prototypes was measured in a muon beam for various ...experimental conditions. Special emphasis was given to study performance aspects related to the trigger capability of the chambers.
The development of the barrel drift chambers for the CMS muon detector at the CERN
Large Hadron Collider is supported by a variety of simulation calculations, based on the GARFIELD drift chamber ...simulation program and the GEANT detector simulation package. This study surveys the results influencing the actual chamber design. The dependence of the drift cell performance on shape and position of the cell electrodes as well as on the mechanical tolerances is shown. The results obtained for space-time relation and spatial resolution are in good agreement to test beam measurements on prototypes.
An overview of the data transfer, processing and analysis operations conducted at the Spanish Tier-1 (PIC, Barcelona) and Tier-2 (CIEMAT-Madrid and IFCA-Santander federation) centres during the past ...CMS CSA06 Computing, Software and Analysis challenge and in preparation for CSA07 is presented.
The 2020 update of the European Strategy for Particle Physics emphasised the importance of an intensified and well-coordinated programme of accelerator R&D, supporting the design and delivery of ...future particle accelerators in a timely, affordable and sustainable way. This report sets out a roadmap for European accelerator R&D for the next five to ten years, covering five topical areas identified in the Strategy update. The R&D objectives include: improvement of the performance and cost-performance of magnet and radio-frequency acceleration systems; investigations of the potential of laser / plasma acceleration and energy-recovery linac techniques; and development of new concepts for muon beams and muon colliders. The goal of the roadmap is to document the collective view of the field on the next steps for the R&D programme, and to provide the evidence base to support subsequent decisions on prioritisation, resourcing and implementation.
The L3 database system
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/1991
Journal Article
Aims.Several experiments have reported observations on possible correlations between the flux of high energy muons and intense solar flares. If confirmed, these observations would have significant ...implications for acceleration processes in the heliosphere able to accelerate protons and other ions to energies of at least tens of GeV. Methods: .The solar flare of the 14 of July 2000 offered a unique opportunity for the L3+C experiment to search for a correlated enhancement in the flux of muons using the L3 precision muon spectrometer. Its capabilities for observing a directional excess in the flux of muons above 15 GeV (corresponding to primary proton energies above 40 GeV) are presented along with observations made on the 14th of July 2000. Results: .We report an excess which appeared at a time coincident with the peak increase of solar protons observed at lower energies. The probability that the excess is a background fluctuation is estimated to be 1%. No similar excess of the muon flux was observed up to 1.5 h after the solar flare time.
Hadron production and lepton-pair production in e+e- collisions are studied with data collected with the L3 detector at LEP at centre-of-mass energies sqrt{s}=192-208GeV. Using a total integrated ...luminosity of 453/pb, 36057 hadronic events and 12863 lepton-pair events are selected. The cross sections for hadron production and lepton-pair production are measured for the full sample and for events where no high-energy initial-state-radiation photon is emitted prior to the collisions. Lepton-pair events are further investigated and forward-backward asymmetries are measured. Finally, the differential cross sections for electron-positron pair-production is determined as a function of the scattering angle. An overall good agreement is found with Standard Model predictions.
The cross section for open-beauty production in photon–photon collisions is measured using the whole high-energy and high-luminosity data sample collected by the L3 detector at LEP. This corresponds ...to 627 pb$^−1$ of integrated luminosity for electron–positron centre-of-mass energies from 189 to 209 GeV. Events containing b quarks are identified through their semi-leptonic decay into electrons or muons. The $e^+e^- _ rightarrow $e^+e^-bb^-X$ cross section is measured within our fiducial volume and then extrapolated to the full phase space. These results are found to be in significant excess with respect to Monte Carlo predictions and next-to-leading order QCD calculations.
The e$^+e^- \to e^+e^-$ hadrons reaction, where one of the two electrons is detected in a low polar-angle calorimeter, is analysed in order to measure the hadronic photon structure function ...$F^\gamma_2$ . The full high-energy and high-luminosity data set, collected with the L3 detector at centre-of-mass energies 189 GeV $\leq \sqrt{s} \leq$ 209 GeV, corresponding to an integrated luminosity of 608/pb is used. The Q$^2$ range 11 GeV$^2 \leq Q^2$ 34 GeV$^2$ and the $x$ range 0.006$\leq x \leq$ 0.556 are considered. The data are compared with recent parton density functions.
PDF
