MULTIPARTICLE IDENTIFICATION WITH ISIS: TESTS WITH THE FULL APERTURE ISIS-1

Results are reported of a successful test of ISIS 1 in a particle beam. ISIS 1 is a full aperture (4 m*2 m) prototype of the particle identifier ISIS (Identification of Secondaries by Ionisation Sampling) , proposed for the European Hybrid Spectrometer (EHS) at the SPS at CERN. Using the 'relativistic rise' of the ionisation loss, electrons and pions at 500 MeV/c were identified with better than 99% confidence, the data containing typically 5-10 tracks per 'picture' drifted by up to 2 m. The ionisation resolution was 12-14% fwhm on 1 m of track and the two track resolution was 2 cm. These results, which agree with our predictions, indicate that ISIS 2 with 5 m of useful track length will be able to distinguish uniquely kaons and protons from pions of known momentum in high multiplicity interactions up to 50 and 100 GeV/c respectively. (14 refs)

Study of the leptonic decays of the ZO Boson

Measurements are presented of the cross section ratios Rℓ = σℓ(e+e-→ℓ+ℓ -)/σhh(e+e-→hadrons) for ℓ = e, μ and τ using data taken from a scan around the Z0. The results are Re = (5.09±0.32±0.18)%, Rμ = (4.96±0.35±0.17)% and Rτ,=(4.72±0.38± 0.29)% where, for the ratio Re, the t-channel contribution has been subtracted. These results are consistent with the hypothesis of lepton universality and test this hypothesis at the energy scale s ∼ 8300 GeV2. The absolute cross sections σℓ(e+e-→ℓ +ℓ-) have also been measured. From the cross sections the leptonic partial widths Γe = (83.2±3.0±2.4) MeV, (ΓeΓμ) 1/2=(84.6±3.0±2.4) MeV and (ΓeΓτ) 1/2=(82.6±3.3±3.2) MeV have been extracted. Assuming lepton universality the ratio Γℓ/Γh=(4.89±0.20± 0.12) × 10-2 was obtained, together with Γℓ=(83.6±1.8±2.2) MeV. The number of light neutrino species is determined to be Nv=3.12±0.24±0.25. Al the data are consistent with the predictions of the standard model.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe

The DELPHI detector at LEP

DELPHI is a 4π detector with emphasis on particle identification, three-dimensional information, high granularity and precise vertex determination. The design criteria, the construction of the detector and the performance during the first year of operation at the large electron positron collider (LEP) at CERN are described. © 1991 - Elsevier Science Publishers B.V. (North-Holland)