Georg Viehhauser

Abstract:

We present a new determination of fDs using 5 million e+e-→cc̄ events obtained with the CLEO II detector. Our value is derived from our new measured ratio Γ(D+s → μ+ν)/Δ(D+s → φπ+) = 0.173 ± 0.023 ± 0.035. Using ß(D+s → φπ+) = (3.6 ± 0.9)%, we extract fDs = (280 ± 19 ± 28 ± 34) MeV. We compare this result with various model calculations.

Abstract:

We have searched for two-body charmless decays of B mesons to purely hadronic exclusive final states including ω or φ mesons using data collected with the CLEO II detector. With this sample of 6.6 ×106B mesons we observe a signal for the ωK+ final state, and measure a branching fraction of B(B+→ωK+)=(1.5−0.6+0.7)±0.2)×10−5We also observe some evidence for the φK* final state, and upper limits are given for 22 other decay modes. These results provide the opportunity for studies of theoretical models and physical parameters. © 1998 American Physical Society.

Abstract:

A limit on the mass of the tau neutrino mντ is derived from 4.5 × 106 tau pairs produced in an integrated luminosity of 5.0 fb-1 of e+e- → γ * → τ+τ- reactions at center of mass energies ≈ 10.6 GeV. The measurement technique involves a two-dimensional extended likelihood analysis, including the dependence of the end-point population on mντ, and allows for the first time an explicit background contribution. We use the the decays τ → 5πντ and τ → 3π2π0ντ to obtain an upper limit of 30 MeV/c2 at 95% C.L. © 1998 Elsevier Science B.V. All rights reserved.

Abstract:

The CLEO collaboration is preparing a major upgrade of its present detector including a RICH detector for particle identification. This subdetector system follows the 'proximity focussing' design and uses Lithium Fluoride (LiF) crystal radiators and MWPCs as photon detectors. These chambers are filled with a CH4/TEA gas mixture and have a Calcium Fluoride (CaF2) crystal photon entrance window. Part of the radiator crystals will have the new 'sawtooth' geometry.We have constructed two of the 30 detector modules and tested these together with the first planar and 'sawtooth' radiator crystals in a muon halo beam at Fermilab. For the measurement of the Cherenkov angle we obtain a single photon measurement error of 13.5 mrad for the conventional planar radiator. With 14 detected photons we find a resolution per track of 4.5 mrad. In the first measurement ever of a 'sawtooth' radiator we achieve a resolution of 11.8 mrad for single photons and 4.8 mrad per track for 12.3 detected photons With a reduced geometric acceptance. These results fulfill CLEO III requirements.

Abstract:

The CLEO detector is undergoing major improvements in conjunction with a high luminosity upgrade of the CESR e+e- collider. A novel element is a state of the art particle identification system, based on a proximity focused Ring Imaging Cherenkov detector. This detector will provide an excellent hadron identification at all the momenta relevant to the study of the decays of B mesons produced at the Υ(4S) resonance. Some features unique to our design will be discussed together with some results achieved on individual components. © 1998 Elsevier Science B.V. All rights reserved.