[en] The UA4 experiment on the measurement of elastic scattering and of the total cross section at the CERN p anti-p Collider is described. The experimental method is discussed, and first results on elastic scattering at low momentum transfer are presented

[en] Proton-antiproton elastic scattering was measured at the centre-of-mass energy √s=546 GeV in the four-momentum transfer range 0.45 ≤-t≤ 1.55 GeV/sup 2/. The shape of the t-distribution is quite different from that observed in proton-proton scattering at the ISR. Rather than a dip-bump structure, a kink is present at -t≅0.9 GeV/sup 2/ followed by a shoulder. The cross section at the second maximum is more than one order of magnitude higher than at the ISR

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[en] A two stage position-sensitive gas proportional counter has been constructed by tightly coupling a Gas Electron Multiplier (GEM) with a Micro-Groove Detector (MGD). The GEM was used as the first amplifying stage and was optimised to transmit close to 100% of the primary charge even at very high drift fields (10 kV/cm). Very narrow GEM-MGD separations (0-600 μm) were used so that the active volume of the detector is still very thin (3-3.6 mm) and the required drift field could be maintained using an acceptable drift voltage (around 4000 V). Very high combined gains (up to 3x10⁵) were obtained with this system. The detector was found to be spark-free in the presence of HIPs (alpha particles) up to gains in excess of 20 000

[en] Some preliminary results are presented of a research on the reaction e⁺e^-→ photons, performed at ADONE, at energy around the 3.1 GeV resonance. Upper limits for the cross-sections of the channels have been obtained; within the limits of the statistics so far collected the results are not inconsistent with the QED predictions. A detailed description of the shower detector that was employed, is also given

[en] Delphi (DEtector with Lepton, Photon and Hadron Identification) is one of the four experiments of the LEP (Large Electron Positron) collider at CERN. The detector is laid out to provide a nearly 4 π coverage for charged particle tracking, electromagnetic, hadronic calorimetry and extended particle identification. The trigger system consists of four levels. The first two are synchronous with the BCO (Beam Cross Over) and rely on hardwired control units, while the last two are performed asynchronously with respect to the BCO and are driven by the Delphi host computers. The aim of this paper is to give a comprehensive global view of the trigger system architecture, presenting in detail the first two levels, their various hardware components and the latest modifications introduced in order to improve their performance and make more user friendly the whole software user interface

[en] We describe a set of large multiwire proportional chambers used in an experiment at the CERN Super Proton Synchrotron. The sensitive area is 2320 x 2320 mm², and four detecting planes, each with different orientation, are grouped together within the same mechanical frame. The number of wires for each module is 5000. Very uniform efficiency over the whole area is achieved by means of a simple mechanical construction. The chambers were operated for a long time without any damage under high particle flux. (orig.)

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[en] A 10x10 cm² MicroGap Chamber with a small stereo angle read-out has been developed for the inner tracking system of CMS. The anode strips are 9 microm wide with a pitch of 200 microm. The sampling pitch of the back cathode is 400 microm at a stereo angle of 50 mrad. Both coordinates are read-out from the same side of the detector substrate. Measurements of gain stability, fraction of induced charge on the back electrode, uniformity of response along the strip and rate capability have been performed in laboratory, using X-ray sources. Detection efficiency, spatial resolution, charge and space correlation have been measured with minimum ionizing particle beams at CERN. Due to the good space and time resolution, high rate capability, 2-D capability and considerable flexibility, this device seems very well suited for the instrumentation of tracking systems. It fulfills almost all the stringent requirements of the next generation of experiments which are being designed for the new high-energy, high luminosity accelerators (LHC and HERA)