A.M. Cartacci

The L3+C detector, a unique tool-set to study cosmic rays

AbstractThe L3 detector at the CERN electron–positron collider, LEP, has been employed for the study of cosmic ray muons.The muon spectrometer of L3 consists of a set of high-precision drift chambers installed inside a magnet with avolume of about 1000 m 3 and a field of 0:5T: Muon momenta are measured with a resolution of a few percentat 50 GeV: The detector is located under 30 m of overburden. A scintillator air shower array of 54 m by 30 mis installed on the roof of the surface hall above L3 in order to estimate the energy and the core position of theshower associated with a sample of detected muons. Thanks to the unique properties of the L3þC detector, muonresearch topics relevant to various current problems in cosmic ray and particle astrophysics can be studied. r 2002Elsevier Science B.V. All rights reserved. PACS: 95.55.Vj; 98.70.Sa; 96.40.Tv; 95.85.RyKeywords: L3+C detector; Cosmic rays; Muon spectrum; Astroparticle physics 1. IntroductionThe L3þ C experiment (Figs. 1 and 2), installedat the Large Electron Positron collider (LEP) atCERN, Geneva, consists of two major parts:firstly, below ground, the L3 muon spectrometer[1], which is comprised of a large 0:5 T magnetwith a volume of 1000 m

The Electron Spectrum From B-meson Decays

The Crystal Ball Collaboration has measured the energy spectrum of electrons from semileptonicB meson decays at thee+e− storage ring DORIS II. Branching ratios and weak mixing angles of the Kobayashi-Maskawa matrix are determined using several models for the hadronic matrix elements. We obtain the branching ratio for semileptonic.B decays to charmed states BR(B→evXc)=(11.7±0.4±1.0)%. Our result for the corresponding Kobayashi-Maskawa matrix element is |Vcb|=0.052±0.006. The model dependence of both results is included in the error. We have not observed semileptonicB decays to non-charmed mesons. Analyzing the measured electron spectrum above 2.4 GeV, where nob→c decays contribute, we find BR(B→evXu)/BR(B→evXc)<6.5% at the 90% confidence level. This corresponds to an upper limit |Vub/Vcb|<0.21.

The optical module for the NESTOR neutrino telescope

NESTOR is a deep-sea water Cherenkov neutrino detector now under construction for deployment in the Mediterranean off Greece. Its key component is an optical module employing a photomultiplier tube with a 15 in. hemispherical photocathode in a transparent glass pressure housing. Extensive tests have been made on the sensitivity, uniformity, time resolution, noise rates and mechanical properties of the module: several test deployments have been made at sea.

Determination ofГ ee of the Υ(1S) and Υ(2S) resonances, and measurement ofR atW=9.39 GeV

AbstractUsing the Crystal Ball detector operating at the DORIS II storage ring we have measured the leptonic partial widthsГee of the Υ(1S) and Υ(2S) resonances. We find

Search for exotic tau decays

\Gamma _{ee} (\Upsilon (1S)) = 1.34 \pm 0.03 \pm 0.06keV

\gamma (e e

and

\Upsilon

\Gamma _{ee} (\Upsilon (2S)) = 0.56 \pm 0.04 \pm 0.02keV.