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We have searched for unstable neutral and charged heavy leptons, N and L ± , and for excited states of neutral and charged leptons, ν * , e * , µ * and τ * , in e + e − collisions at centre-of-mass energies of 170 and 172 GeV using the OPAL detector at LEP. No evidence for their existence was found. From the analysis of charged-current decays of(More)
Production of events with hadronic and leptonic final states has been measured in e+e− collisions at centre-of-mass energies of 130–172 GeV, using the OPAL detector at LEP. Cross-sections and leptonic forward-backward asymmetries are presented, both including and excluding the dominant production of radiative Zγ events, and compared to Standard Model(More)
This paper overviews the spectrum of robotics programs at the Israel National Museum of Science, Technology and Space (MadaTech), including exhibitions for visitors and educational activities at the Gelfand Center for Model Building, Robotics & Communication. We present the 2010 robotics program and describe in detail the innovative nationwide robotics(More)
A search is described to detect charged Higgs bosons via the process e + e − → H + H − , using data collected by the OPAL detector at center-of-mass energies of 130−172 GeV with a total integrated luminosity of 25 pb −1. The decay channels are assumed to be H + → qq ′ and H + → τ + ν τ. No evidence for charged Higgs boson production is observed. The lower(More)
We present an observation at LEP of the production of χc2 mesons in the collisions of two quasireal photons using the OPAL detector. The χc2 mesons are reconstructed in the decay channel χc2 → J/ψ γ → l l γ (with l = e, μ) using all data taken at ee centre-of-mass energies of 91 and 183 GeV, corresponding to integrated luminosities of 167 and 55 pb(More)
Photonic events with large missing energy have been observed in e + e − collisions at centre-of-mass energies of 130, 136 and 183 GeV collected in 1997 using the OPAL detector at LEP. Results are presented for event topologies with a single photon and missing transverse energy or with an acoplanar photon pair. Cross-section measurements are performed within(More)
Gluon jets are identified in ee hadronic annihilation events by tagging two quark jets in the same hemisphere of an event. The gluon jet is defined inclusively as all the particles in the opposite hemisphere. Gluon jets defined in this manner have a close correspondence to gluon jets as they are defined for analytic calculations, and are almost independent(More)
We have constructed and installed a pressurized straw vertex chamber in the Mark III experiment at the SLAC e+estorage ring SPEAR. The chamber consists of 12 concentric layers of straws, arrayed at radii between 5.4 cm and 13.0 cm from the interaction point. There are a total of 640 straws, each 8 mm in diameter and 84 cm long. We obtain an overall spatial(More)