Experience with the L3 vertex drift chamber at LEP

Abstract

The vertex drift chamber of the L3 Experiment at LEP, based on the time expansion principle, was in operation from the start-up of LEP in 1989 until the shutdown of LEP in 2000. The gas mixture used was 80% CO 2 and 20% i-C 4H 10 at a pressure of 1200 mbar . We present the design of the chamber, the infrastructure and the performance during the 11 years of operation. The total radiation received on the anode wires was ∼10 −4 C/ cm . No degradation of the anode pulse amplitude, wire efficiencies and resolution was observed for the whole running period.