G. Anzivino

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.

The LVD tracking system chambers

ICSCWorldLaboratory, Lausanne, SwitzerlandReceived5 November 19921. IntroductionThe LVDdetector[11 can be defined as an under-groundobservatory with the main objectives of study-ing neutrinos from stellar collapse and searching forpoint-like sources of gammas and neutrinos of veryhigh energy. This multipurpose apparatus is being in-stalled in hall Aofthe Gran Sasso Laboratory [21 at avertical depth of 3600 m.w.e. It consists of a largevolume of liquid scintillator divided into modules andofa tracking system madeof layers ofstreamertubes.The detectordesignfulfils the following aims:- the study ofthe neutrino interactions inside thedetectorwithenergymeasurementfor low-energyneu-trino interactions, and patternidentification for higherenergyevents;- the detectionofpassing muonswith track recon-struction, up-down discrimination and time of flightmeasurement.The apparatus consists of 190 basically identicalmodules. Each module comprises 9.6 t ofliquid scintil-lator divided into eight modular counters and an L-shaped tracking chamber, containing adouble layer ofstreamer tubes andfacingthe bottom andone verticalside ofthemodule. Thesemodules areinserted into an0168-9002/93/

Energy and scale dependence of heavy-quark production in QCD

06.00 0 1993 -Elsevier Science Publishers B.V. All rights reservediron support structure. The whole array, which mea-sures 40X 12

Hadron distributions in the final state of DIS at HERA

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

Intrinsic charm in pp and γp interactions

\bar pp

Limited streamer chambers for the Large Volume Detector

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.

Single and multiple muon events in the LVD detector

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.

The depth-intensity distribution of single and double muon events measured by the LVD underground experiment in the Gran Sasso laboratory

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.