The Outer Tracker detector of the HERA-B experiment—Part I: Detector

Abstract

The HERA-B Outer Tracker is a large system of planar drift chambers with about 113 000 read-out channels. Its inner part has been designed to be exposed to a particle flux of up to 2 · 10 5 cm −2 s −1 , thus coping with conditions similar to those expected for future hadron collider experiments. 13 superlayers, each consisting of two individual chambers, have been assembled and installed in the experiment. The stereo layers inside each chamber are composed of honeycomb drift tube modules with 5 and 10 mm diameter cells. Chamber aging is prevented by coating the cathode foils with thin layers of copper and gold, together with a proper drift gas choice. Longitudinal wire segmentation is used to limit the occupancy in the most irradiated detector regions to about 20 %. The production of 978 modules was distributed among six different laboratories and took 15 months. For all materials in the fiducial region of the detector good compromises of stability versus thickness were found. A closed-loop gas system supplies the Ar/CF 4 /CO 2 gas mixture to all chambers. The successful operation of the HERA-B Outer Tracker shows that a large tracker can be efficiently built and safely operated under huge radiation load at a hadron collider.

Measurement of D0, D+, Ds + and D*+ production in fixed target 920 GeV proton–nucleus collisions

“…The wires were positioned in the beam halo, and their distance to the beam core was automatically adjusted to maintain a constant interaction rate. Details of the various subdetectors have been published [16,17,18,19,20,21], so only a brief overview of the apparatus is given here.…”

“…The first tracking chamber was upstream of the magnet, and the remaining six chambers were downstream of the magnet between 7 m and 13 m from the interaction region. Due to a large variation of particle flux density, the tracking system was divided into a finegrained inner tracker (ITR), using microstrip gas chambers with gas electron multipliers and ∼300 µm pitch [17], and a coarse-grained outer tracker (OTR), using honeycomb drift cells with 5 mm and 10 mm cell diameters [18]. The obtained momentum resolution can be parameterised as σ p /p = (1.61 + 0.0051 · p [GeV/c]) % [18], where p is the particle momentum.…”

A study of the Millepede alignment algorithm on the Monte Carlo model of the HERA-B outer tracker

“…The outer part of HERA-B main tracker (OTR) is designed to detect charged particle tracks with distance from proton beam r 20 cm [2].…”

“…The latter is separated into an inner tracker (ITR) close to the proton beam pipe and outer tracker (OTR) farther out. The HERA-B Outer Tracker uses honeycomb drift chambers [2]. Pattern recognition Chambers (PC) of OTR are made of 998 separate sensitive planes.…”

The Outer Tracker detector of the HERA-B experiment. Part II: Front-end electronics

“…Detector description: The Outer Tracker of HERA-B [1,3] is composed of 13 planar superlayers ( Fig. 1) of drift tube modules comprising 112,674 readout channels.…”