A. Cardini

The electromagnetic calorimeter of the NOMAD experiment

Abstract A description is given of the NOMAD electromagnetic calorimeter, consisting of 875 lead-glass counters read out by two-stage photomultipliers and a low noise electronic chain. The detector operates in a 0.4 T magnetic field transverse to the counter axis. The paper discusses the design criteria, the lead-glass characteristics, the properties of the read out chain and provides a summary of the calorimeter performance.

A HIGH STABILITY LIGHT EMITTING DIODE SYSTEM FOR MONITORING LEAD GLASS ELECTROMAGNETIC CALORIMETERS

Abstract We have designed, built and tested a high stability system based on blue light emitting diodes (LED) and current pulse generators for calibration and monitoring of lead-glass calorimeters. This apparatus is presently being used for the electromagnetic calorimeter of the WA96 (NOMAD) experiment at CERN. The system was developed to minimize the sensitivity to temperature variations, different loadings, and ageing effects. Tests performed both in the laboratory and in the experiment showed that the response of the lead-glass calorimeter modules to LED light pulses could be kept within the precision of ±1% for periods of several months.

Progress on high-resolution tracking with scintillating fibres: a new detector based on capillaries filled with liquid scintillator

Abstract The capabilities of a new detector based on capillaries filled with liquid scintillator have been investigated. Tests have been performed using various scintillating cocktails and readout systems. With the best combinations, and for light propagation over a few centimetres, the hit density is as high as 5 hits/mm. For propagation over distances greater than 10 cm, an attenuation length of ∼95 cm is measured. A spatial resolution of σ ≅ 12 μ m is obtained with capillaries of 20 μm bore.

Sources of noise in high resolution tracking with scintillating fibres

Abstract Noise generated in the WA84 scintillating fibre vertex detector has been studied both experimentally and theoretically. The different sources of noise have been identified, and their relative contributions determined. Methods of noise reduction are considered.

WA84 experiment: A beauty search with a scintillating-fibre microvertex detector

Abstract This paper gives a review of the physics aims of the fixed-target experiment WA84, currently being conducted at CERN, and of the methods used. The operation and performance of the scintillating-fibre microvertex detector are described.

Comparison of glass and plastic scintillating microfibres for high-resolution tracking

Abstract The WA84 experiment at CERN has been proposed as a study of heavy-flavour physics using a novel, high-resolution vertex detector, consisting of an active target assembled from coherent bundles of scintillating optical microfibers. This paper is a presentation of work carried out in the development of the vertex detector. Results from tests of prototypes of the detector in a charged-particle beam are reported, and the differences in the performance of glass and plastic active targets are discussed.

A high-resolution tracking detector based on capillaries filled with liquid scintillator

Abstract Results are presented on tests in a 5 GeV/c hadron beam of a high-resolution tracking detector constructed from 20 μm diameter glass capillaries filled with liquid scintillator. Details are given of the techniques used to eliminate noise in the readout system and to reduce cross-talk between capillaries. A spatial resolution of 15 μm is obtained.

Hadron detection with a dual-readout fiber calorimeter

Abstract In this paper, we describe measurements of the response functions of a fiber-based dual-readout calorimeter for pions, protons and multiparticle “jets” with energies in the range from 20 to 180 GeV. The calorimeter uses lead as absorber material and has a total mass of 1350xa0kg. It is complemented by leakage counters made of scintillating plastic, with a total mass of 500xa0kg. The effects of these leakage counters on the calorimeter performance are studied as well. In a separate section, we investigate and compare different methods to measure the energy resolution of a calorimeter. Using only the signals provided by the calorimeter, we demonstrate that our dual-readout calorimeter, calibrated with electrons, is able to reconstruct the energy of proton and pion beam particles to within a few percent at all energies. The fractional widths of the signal distributions for these particles ( σ ∕ E ) scale with the beam energy as 30 % ∕ E , without any additional contributing terms.

Application of a scintillating-fibre detector to the study of short-lived particles

Abstract The technique of particle tracking with scintillating fibres is described and its application to the study of short-lived particles is illustrated using results obtained in the WA84 experiment at CERN.

Use of a high-resolution, scintillating-fibre, tracking detector in recording π−-nucleon interactions at √s ≈ 26 GeV

Abstract A scintillating-microfibre, tracking detector has been used at the CERN Omega spectrometer to record the interactions of 340 GeV/ cπ − particles incident on a fixed target. The detector - based on coherent bundles of ∼36 μ m diameter, PMP-doped plastic fibres - was oriented so as to give views of interactions in the plane perpendicular to the incoming pions. Additional event information was provided by a series of 20 and 50 μm pitch silicon-microstrip detectors, placed near to the fibres, and by the spectrometer. An account is given of the contribution of the scintillating-fibre device in obtaining full event reconstruction.