J.M. Morton

RADIAL WIRE DRIFT CHAMBERS FOR THE H1 FORWARD TRACK DETECTOR AT HERA: DESIGN, CONSTRUCTION AND PERFORMANCE

Abstract The Forward Track Detector (FTD) in the H1 experiment at the HERA electron-proton collider includes three large radial wire drift chambers for accurate charged track reconstruction and particle identification. The chambers achieve the simultaneous requirements of good space point determination and good pulse height measurement. The latter is exploited for enhanced electron/hadron discrimination using X-ray emission from a transition radiator which precedes each chamber. The design, assembly and operating characteristics of the chambers are described.

Simultaneous track reconstruction and electron identification in the H1 radial drift chambers

Abstract Results of prototype tests of the radial-wire drift chambers of the H1 forward track detector are presented. Choice of a suitable gas mixture and careful design of the chambers to include the possibility of efficient X-ray detection have shown that tracks can be reconstructed with good accuracy (σ ≈ 110–150 μm) and that simultaneously electron identification can be achieved by pulse integral analysis of ionization energy deposition due to both dE/dx and transition radiation. For 90% electron acceptance the pion contamination is 8% at high momentum (≈ 60 GeV/c). At lower momenta, electron identification is further enhanced by the multiple sampling of pulse integrals in such chambers, resulting at 5 GeV/c in a pion contamination of ≈ 0.5%.

Precision reconstruction of charged tracks with simultaneous electron identification in a gaseous detector using transition radiation

Abstract Results are presented from tests of a radial wire drift chamber, the design of which is optimised for both accurate spatial reconstruction of charged tracks and efficient detection of incident X-rays. With flash digitised readout, we demonstrate that analysis of pulse profile can yield good spatial accuracy (σ drift ∼150μm, σ chdiv ∼1% wire length) together with useful hadron/electron discrimination if(π/e∼8% at 60 GeV> c ) using a transition radiator immediately preceding the chamber. The exploitation of this technique at high energy proton-proton and electron-proton collider storage rings is briefly discussed.

e+- identification using the drift chambers and transition radiators of the H1 forward track detector

The status of the operation and performance of the H1 Forward Track Detector at the HERA ep storage rings for the detection of electrons (e−) and positrons (e+) is reported. Events with charged particles produced at small angles (7° 3 GeV. Transition radiation X-rays, produced in polypropylene foil radiators immediately upstream of each radial wire drift chamber, are detected in the latter as ionisation charge additional to the usual dEdx contribution. Progress towards achieving the design eπ discrimination of better than 10% π contamination for 90% e± acceptance, which has been established with single tracks, in the complex multi-track environment of ep events at HERA, is reported.

Electron identification in the H1 radial wire drift chambers

Abstract Tests of a radial wire drift chamber for the H1 experiment at the HERA ep-collider were performed at a test beam at the CERN SPS. These types of chambers, part of the H1 forward track detector, are designed to determine accurate vector track segments and to identify electrons by means of d E d x and transition radiation (TR) detection. The electron/pion discrimination has been evaluated at particle momenta from 5 to 50 GeV/c using gas mixtures containing 15 to 30% xenon. Methods and results of this analysis are presented.

Spatial precision of H1 radial wire drift chambers using gas mixtures suitable for transition radiation detection

Abstract Results are presented from calibration and tests of a radial wire drift chamber for the H1 experiment at the HERA ep collider. The chambers form part of the H1 forward track detector (FTD) and are designed both to determine accurate vector track segments and to identify simultaneously electrons by means of d E d x measurement and transition radiation (TR) detection. The spatial reconstruction accuracy (from drift timing and charge division) has been investigated using gas mixtures suitable for TR X-ray detection. A novel technique for enhancing the precision of determination of the radial (non-drift) coordinate of each track using the drift cell geometry is evaluated. A brief summary of the performance of the three radial wire chambers in the FTD is given.

Radial wire drift chambers with fast gases for tracking at future supercolliders

Abstract We report on progress in the development of wire-based tracking in the forward region of experiments at future supercolliders. Results are presented from experimental studies of candidate fast drift gases in crossed electric and magnetic fields, and on the operation of a prototype “wedge” of a radial wire drift chamber cell.