S.A. Kononov

Status of the KEDR detector

Abstract KEDR is a general-purpose detector for experiments at the VEPP-4M e + e − -collider in the energy range 2 E =2.0– 12 GeV . All detector subsystems (except the aerogel Cherenkov counters) have been installed into the detector at VEPP-4M. Some preliminary data have been taken in the energy region of the J/Ψ meson. The tuning of the detector and the VEPP-4M collider is in progress. Preliminary results on the detector performance are presented. The future experimental program for the KEDR detector is discussed.

Aerogel Cherenkov counters for the KEDR detector

Abstract The project of Cherenkov counters based on Aerogel, wavelength SHIfter, and PHotomultiplier (ASHIPH) for the KEDR detector is described. The Monte Carlo simulation of number of photoelectrons was carried out. The first counters have been produced. Measurements with cosmic particles were performed. As compared with the direct light collection on PMT, the ASHIPH method allows the diminishment of the number of PMTs essentially. The optical properties of aerogels produced at KEK and at Novosibirsk are presented.

Measurement of the τ lepton mass at the KEDR detector

A precise τ lepton mass measurement performed at the VEPP-4M collider with the KEDR detector is reported. The mass value is evaluated from the τ+τ− cross section behavior around the production threshold. The result based on 6.7 pb−1 of data is mτ = 1776.81−0.23+0.25 ± 0.15 MeV. Using 0.8 pb−1 of data collected at the ψ′ peak, we have also determined that ΓeeBττ(ψ′) = 9.0 ± 2.6 eV.

ASHIPH counters for the KEDR detector

Abstract The status of the ASHIPH (Aerogel, wavelength SHIfter, and PHotomultipliers) system of the KEDR detector is described. The measurement of the quality of the particle identification with the ASHIPH counters was performed. The π/K separation is 4.5σ for the momentum 1.2 GeV /c and 4.7σ for the momentum 0.86 GeV /c . Timing properties of the ASHIPH counter are measured. The time resolution for pions is 2 ns , and the BBQ decay time is 15 ns . The advantages and disadvantages of Cherenkov counters filled with aerogel crumb are discussed. The process of the mass counter production for the KEDR detector is described.

Test of aerogel counters for the KEDR detector

The project of Cherenkov counters based on Aerogel, wavelength SHIfter, and PHotomultipliers (ASHIPH) for the KEDR detector is described. The quality of particle identification with the ASHIPH counters has been measured for the first time. Tests have been carried out at the Dubna accelerator. For a momentum of 1.2GeV/c, the π/K separation is 4.5σ. In comparison with direct light collection on PMTs, the ASHIPH method allows to diminish the number of PMTs essentially.

Development of threshold aerogel Cherenkov counters ASHIPH for the SND detector

The paper is devoted to the development of Cherenkov counters based on the Aerogel, wavelength SHIfters and PHotomultiplier tubes (ASHIPH) for the SND detector at VEPP-2000. The ASHIPH counter system for the SND detector is designed. The counters will separate p and K mesons in the momentum range from 300 to 900 MeV=c: Optical properties of aerogel samples with refraction index 1.13 are measured and results are presented. As photodetectors, the microchannel plate photomultipliers with multialkali photocathodes are used. Monte Carlo simulation of the ASHIPH counter predicts more than 7 photoelectrons for a relativistic particle. r 2002 Elsevier Science B.V. All rights reserved. PACS: 29.40.Ka

Measurement of the ratio of the leptonic widths

The ratio of the electron and muon widths of the

\Gamma_{ee}/\Gamma_{\mu\mu}

J/\psi

for the

meson has been measured using direct

J/\psi

J/\psi