[en] The architecture of a multiprocessor system is described that will be used for on-line filter and second stage trigger applications. The system is based on the MC 68000 microprocessor from Motorola. Emphasis is paid to hardware aspects, in particular the modularity, processor communication and interfacing, whereas the system software and the applications will be described in separate articles. (orig.)

[en] The electronics system for the readout of a large drift chamber (25 m³, 6110 sense wires) with image readout, to be used at the CERN p-anti p collider, is described. The system uses a flash analog-to-digital converter and is able to measure directly the drift time, the charge division, and the energy losses for many tracks on each wire. The results obtained with chamber and electronics prototypes are reported. (orig.)

[en] Reliable operation of RAMs as shift registers can be obtained up to frequencies exceeding 125 MHz using standard binary coded addressing. (orig.)

[en] The architecture of a readout system is described which will be used in conjunction with the muon detector in the UA-1 experiment at the anti pp collider at CERN. In addition to measuring drift time for spatial information, the system provides a fast trigger (< 1 μs after drift time) and a second level trigger decision based on a fast microprocessor. The fast trigger part allows the use of the muon detector as an active trigger element, while a second level trigger decision using detailed digitizer data is included for adequate reduction of the trigger rate. The multipole time digitizer (MTD) is based on the use of fast RAMs (256 x 4) as 125 MHz shift registers, giving time bins of 8 ns and a time range of 2 μs (256 x 8 ns). The high input rate has imposed a fast readout and transfer to a buffer in the controller. The data in this buffer is reordered according to wire number and corresponding times. Together with look-up tables this allows fast processing of the data for a second level trigger. (orig.)

[en] A second level trigger system using conventional wire chamber readout and NIM modules is described. The events to be processed by the on-line computer are selected in a time interval of one microsecond on the basis of number of hits in the wire chambers. Some applications and performances of the system are described in detail. (orig.)

[en] A large scintillating fibre detector consisting of ≅ 60000 scintillating plastic fibres of 1 mm diameter and 2.4 m length has been used successfully as a tracking and preshower detector in the UA2 experiment at CERN. The detector readout, the pattern recognition algorithm and the results from the anti pp data taking run are described. (orig.)

[en] A large scintillating-fibre detector consisting of ≅ 60000 scintillating plastic fibres of 1 mm diameter and 2.4 m length has been used successfully as a tracking and preshower detector in the UA2 experiment at CERN. The detector readout and the results from the anti pp data-taking run are described. (orig.)

[en] A large scintillating fibre detector for the UA2 experiment at the CERN anti pp Collider is under construction. It will be used for tracking and electron identification. The performance of a full scale test module containing 960 fibres of 2.1 m length and 1 mm diameter is described. (orig.)

[en] The UA2 experiment at CERN is currently upgrading its apparatus to take advantage of the higher accelerator luminosity to be provided from November 1987. The first large particle tracking detector using scintillating optical fibres will form a major part of this upgrade. The detector is built by the Cambridge, CERN and Saclay groups. The Scintillating Fibre Detector is a cylinder of radius 38 to 44 cm, composed of 60000 plastic optical fibres of length over 2 m. The 1 mm diameter fibres are optically clad and aluminised, and are arranged in 24 layers. The detector will be used to track charged particles produced in anti pp interactions, and also contains a lead converter to cause neutral and charged electromagnetic particles to shower. The signals from the fibres are amplified, multiplexed and digitised by 32 readout chains. These consist of: A large aperture, de-magnifying image intensifier, providing a gain of ≅ 40000. Extremely fast phosphors are employed for the three stages, to match the short time (4 μs) between particle interactions; Charge-coupled devices (CCDs) converting the optical image into a single train of electrical pulses for 2000 fibres. A novel use of the anti-blooming electrode of the CCD enables unwanted images to be cleared in <1 μs; A Fastbus digitiser, which processes the video signal, providing a large degree of data reduction. A full-scale prototype of 960 fibres with readout has been tested in a particle beam. It has demonstrated a good spatial resolution of the tracks (<0.20 mm), and an excellent discrimination between electrons and hadrons based on the light detected after the converter. (orig.)

[en] The design, construction, and commissioning of the ALICE Time-Projection Chamber (TPC) is described. It is the main device for pattern recognition, tracking, and identification of charged particles in the ALICE experiment at the CERN LHC. The TPC is cylindrical in shape with a volume close to 90 m³ and is operated in a 0.5 T solenoidal magnetic field parallel to its axis. In this paper we describe in detail the design considerations for this detector for operation in the extreme multiplicity environment of central Pb-Pb collisions at LHC energy. The implementation of the resulting requirements into hardware (field cage, read-out chambers, electronics), infrastructure (gas and cooling system, laser-calibration system), and software led to many technical innovations which are described along with a presentation of all the major components of the detector, as currently realized. We also report on the performance achieved after completion of the first round of stand-alone calibration runs and demonstrate results close to those specified in the TPC Technical Design Report.