Accelerator Neutrinos

Abstract:

We present a new determination of f^Ds 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:

A first level trigger system based on a 40 MHz digital pipeline has been developed for the CERN NA48 [1] experiment, aiming at measuring CP violation in K-0 --> 2 pi decays.The outputs of the 13340 cells of the 10 m(3) liquid krypton calorimeter are summed into 64 X and 64 Y projection strips and continuously digitised with 40 MHz FADCs.This information is used to reconstruct at each clock cycle and for the two calorimeter projections, the number of clusters, the impact time of each of them (with a precision of about 3 ns), their total energy and the first and second moments of the energy distribution.Based on the quantities listed above, a programmable look-up table system subsequently computes online the longitudinal position of the kaon decay vertex and performs an event selection.The system is described.

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.