The OPAL Silicon Strip Microvertex Detector with Two Coordinate Readout

The OPAL experiment at the CERN LEP collider recently upgraded its silicon strip microvertex detector from one coordinate readout ( only) to two coordinate readout ( and z). This allows three dimensional vertex reconstruction and should improve lifetime measurements as well as b quark jet identi cation. This paper describes the new microvertex detector system with emphasis on the novel techniques and new components used to obtain the second coordinate information. These include the use of back-to-back single-sided detectors with orthogonally oriented readout strips, a gold printed circuit on a thin glass substrate to route the z strip signals to the electronics at the end of the detector, and the use of MX7 readout chips. Results on the performance of the new detector are presented. (To Be Submitted to Nuclear Instruments and Methods)