The DELPHI Silicon Tracker at LEP2

Abstract

Yves was one of the driving forces during the design and construction of the Silicon Tracker. He was killed in an avalanche on the Pointe Percee in January 1996, a victim of his passion for the high mountains. We would like to dedicate this paper to his memory. AbstractThe DELPHI Silicon Tracker, an ensemble of microstrips, ministrips and pixels, was completed in 1997 and has accumulated over 70 pb 1 of high energy data. The Tracker is optimised for the LEP2 physics programme. It consists of a silicon microstrip barrel and endcaps with layers of silicon pixel and ministrip detectors. In the barrel part, three dimensional b tagging information is available down to a polar angle of 25 . Impact parameter resolutions have been measured of 28 m 71= (p sin 3 2 ) m i n R and 34 m 69=p m i n Rz, where p is the track momentum in GeV=c. The amount of material has been kept low with the use of double-sided detectors, double-metal readout, and light mechanics. The pixels have dimensions of 330 330 m 2 and the ministrips have a readout pitch of 200 m. The forward part of the detector shows average e ciencies of more than 96%, has signal-to-noise ratios of up to 40 in the ministrips, and noise levels at the level of less than one part per million in the pixels. Measurements of space points with low backgrounds are provided, leading to a vastly improved tracking e ciency for the region with polar angle less than 25 .3

Measurements of CP-conserving trilinear gauge boson couplings WWV (V≡γ,Z) in e+e− collisions at LEP2

“…For LEP2 operation a number of changes were made to the sub-detectors, the trigger [13], the run control system and the track reconstruction algorithms to improve the performance. The angular coverage of the Vertex Detector was extended [14] to cover polar angles 1 in the range 11 • < θ < 169 • with the inclusion of the Very Forward Tracker. Together with improved tracking algorithms, alignment and calibration procedures, this resulted in an increased track reconstruction efficiency in the forward region of DELPHI.…”

Silicon tracking detectors—historical overview

“…The first DELPHI vertex detector, consisting of two layers of single-sided strip detectors (192 detectors with 55,296 readout channels altogether) was constructed in 1989; it went through several upgrades and finally, in 1996, a 1.7 m 2 detector was built out of 888 detectors, with 1,399,808 readout channels (736 strip detectors with 174,080 readout channels, and 1,225,728 pixels)-see Fig. 8 [48].…”

High spatial resolution detectors and particle lifetime measurements at LEP

“…The z strips were rerouted to the end of the face using a thin polyamide fanout glued on top of the sensors and wire-bonded to the strips. The DELPHI silicon tracker [5], first installed in 1989, was continuously upgraded, evolving from two to three layers and single-sided to double-sided. The final LEP2 configuration consisted of a three layer microstrip vertex detector in the barrel, and a Very Forward Tracker (VFT) of two layers of ministrip and pixel sensors in the endcaps.…”