E. Katsoufis

The Barrel Ring Imaging Cherenkov counter of DELPHI

Abstract A short explanation is given of the Barrel Ring Imaging CHerenkov (BRICH) detector and its performance. We discuss in brief some of the requirements to run this detector. Special attention is paid to the functioning of the Cherenkov photon detector — a photosensitive gas-filled drift chamber where the photoelectrons drift to a MWPC of special construction. We illustrate the BRICH performance with some preliminary results.

Extensive performance studies for the ATLAS BIS-MDT precision muon chambers with cosmic rays

ATLAS (A Toroidal LHC ApparatuS) is a general-purpose experiment, which will start its operation at the Large Hadron Collider (LHC) at CERN in 2007. The ATLAS detector is designed to explore numerous physics processes by measuring, recording, and investigating the products emerging from proton-proton collisions at energies up to 14 TeV. High-precision muon momentum measurement (dp/p-10% at p/sub T/=1 TeV/c) over large areas using Monitored Drift Tube (MDT) chambers is crucial for the ATLAS experiment. More than 1,200 MDT chambers, assembled from approximately 370,000 drift tubes operated at 3 bar pressure, will be used to provide for the total detector coverage of 5,500 m/sup 2/. Three Greek universities have taken the responsibility to construct 30,000 drift tubes of /spl sim/1.7 in length, to test them and finally assemble them into 120 BIS (Barrel Inner Small) chambers. The design of the muon drift tubes aims at high efficiency (>95%) and a spatial resolution of <80 /spl mu/m (single tube resolution). This paper describes the cosmic ray setup, which has been instrumented in order to verify. that the BIS chamber Module-0 fulfils its design requirements. The analysis of its data shows that the chamber meets these requirements; it has low noise levels, uniform drift properties, good spatial resolution and high particle detection efficiency.

Recent results from the DELPHI barrel ring imaging Cherenkov counter

The DELPHI detector installed in the LEP (Large Electron-Positron Collider) is equipped with RICH (ring imaging Cherenkov) counters. The barrel part incorporates a liquid (C/sub 6/F/sub 14/) and a gaseous (C/sub 5/F/sub 12/) radiator, providing particle identification up to 20 GeV/c. The Cherenkov photons of both radiators are detected by TPC (time projection chamber)-like photon detectors. The drift gas (75% CH/sub 4/+25% C/sub 2/H/sub 6/) is doped with TMAE (tetrakis-dimethylamine-ethylene) by which the ultraviolet Cherenkov photons are converted into single free photoelectrons. These are drifted towards multiwire proportional chambers at the end of the drift tubes, and the space coordinates of the conversion point are determined. One half of the barrel RICH is now equipped with drift tubes and has provided results from the liquid radiator since spring 1990. The gas radiator has been tested with C/sub 2/F/sub 6/ as a preliminary filling since August 1990. The data obtained demonstrate the good particle identification potential. For the liquid radiator, the number of detected photons per ring in hadron jets is N=8, whereas for muon pairs (single tracks) N=10 has been obtained. For the gas radiator, 2.1 photons per track were observed, which demonstrates good functioning of the focussing mirrors. >

Performance of the Barrel Ring Imaging Cherenkov counter of DELPHI

The Barrel Ring Imaging Cherenkov detector of the DELPHI experiment at LEP provides particle identification by the detection of the radiation emitted in UV transparent perfluorocarbons. We will present the principles of the operation of the detector together with a discussion of the automatized control of all the relevant physical parameters. The observed performances of the detector are very close to their design values. >