The precision tracker of the OPERA detector

The Precision Tracker of the muon spectrometer of the OPERA detector consists of ∼ 10000 aluminum drift tubes of 8 m length. They have an outer diameter of 38 mm and a wall thickness of 0.85 mm. The challenge of the detector design originates from the 8 m length of the drift tubes, a detector length, which has not been used before. Tight mechanical tolerances for positioning and alignment of the signal wires are required in order to make a significant measurement of the sign of the muon charge. tector is manufactured in modules, which are 50 cm wide, each consisting of four adjacent drift tube planes. This guarantees high efficiency and complete rejection of the left–right ambiguity. The details of the novel mechanical design are described in this paper. fety reasons, the drift tubes are operated with an Argon / CO 2 gas mixture. The gas volume of the drift tubes is entirely sealed with O-rings, in order to avoid ageing problems. The total gas volume amounts to about 80 m 3 . ont end electronics of the drift tubes consist of a bootstrap amplifier followed by a commercial ultrafast comparator. Thus only digital LVDS signals are transmitted over large distances. ort on the development and performance of the first two prototype modules of the precision tracker including test measurements of the resolution and efficiency obtained.