D. Boscherini

The ZEUS vertex detector: Design and prototype test

Abstract A gas vertex detector, operated with dimethylether (DME) at atmospheric pressure, is presently being built for the ZEUS experiment at HERA. Its main design features, together with the performances of a prototype measured at various operating voltages, particle rates and geometrical conditions on a CERN Proton Synchrotron test beam, are presented. A spatial resolution down to 35 μm and an average wire efficiency of 96% have been achieved, for a 3 mm gas gap relative to each sense wire.

A high resolution, low power time-of-flight system for the space experiment AMS

The system of plastic scintillator counters for the AMS experiment is described. The main characteristics of the detector are: (a) large sensitive area (four 1.6 m2 planes) with small dead space; (b) low-power consumption (150 W for the power and the read-out electronics of 336 PMs); (c) 120 ps time resolution. ( 1999 Elsevier Science B.V. All rights reserved.

A new gaseous detector for tracking: The blade chamber

Abstract As part of the LAA project at CERN a prototype of a streamer-chamber in which a blade, instead of a wire, is used as the amplification electrode has been built. A big advantage is that the blade can be bent to follow a curve so that a chamber can be built with cells ideally matched to the geometry of the experiment. Moreover, a blade is very rugged, it can withstand severe mechanical shocks and it is also resistant to damage by sparks. The drift time has been measured and a spatial resolution of 250 μm has been achieved. Left-right ambiguity can be solved by measuring the charge asymmetry on the walls. The coordinate along the blade is read by external pickup strips.

Energy and scale dependence of heavy-quark production in QCD

SummaryWe consider the energy dependence of charm and beauty production cross-sections in pp or

Monte carlo simulations for leading proton production in deep inelastic scattering

\bar pp

Multi-jet rates in deep inelastic scattering and in e+e− annihilation

collisions up to √s=200 TeV for different values of the scale μ2, using different proton structure functions. The cross-sections are computed accounting for leading-order and next-to-leading order perturbative QCD contributions. The values ofK-factors increase significantly with the energy for relatively small scale values, μ2≈M2, whereM is the heavy-quark mass, and do not practically depend on the energy for higher values, μ2=4M2−8M2. The calculated cross-sections as functions of the energy for different values of μ2 have a common crossing point if the gluon structure functions used have proper Altarelli-Parisi μ2-evolution. The same holds true when considering the energy and scale dependence of the heavy-quark cross-sections in high-energy photoproduction.

Measurement of inelastic J/ψ production in deep inelastic scattering at HERA

SummaryMomentum distributions of secondary hadrons produced in deep inelastic scattering (DIS) are studied for both current and target fragmentation regions. They are shown to contain interesting information on several important questions of hadroproduction dynamics such as target stucture and hadronization mechanism. Special emphasis is given to the HERA kinematical region.

Measurement of the reaction y*p-+dpp in deep inelastic e+p

SummaryPredictions for «leading» proton production in Deep Inelastic Scattering at HERA energies are presented in the framework of different Monte Carlo event generators,i.e. LEPTO, HERWIG and PYTHIA, in terms of Feynman-x and transverse-momentum distributions. In order to get a comprehensive picture of the various possibilities, different structure functions, differentQ2-values, different reference frames and different types of events (minimum-bias events and events with charm and beauty, separately) are considered.