The DELPHI silicon strip microvertex detector with double sided readout

The silicon strip microvertex detector of the DELPHI experiment at the CERN LEP collider has been recently upgraded from two coordinates (RΦ only) to three coordinates reconstruction (RΦ and z). The new Microvertex detector consists of 125 952 readout channels, and uses novel techniques to obtain the third coordinate. These include the use of AC coupled double sided silicon detectors with strips orthogonal to each other on opposite sides of the detector wafer. The routing of signals from the z strips to the end of the detector modules is done with a second metal layer on the detector surface, thus keeping the material in the sensitive area to a minimum. Pairs of wafers are daisy chained, with the wafers within each pair flipped with respect to each other in order to minimize the load capacitance on the readout amplifiers. The design of the detector and its various components are described. Results on the performance of the new detector are presented, with special emphasis on alignment, intrinsic precision and impact parameter resolution. The new detector has been taking data since spring of 1994, performing up to design specifications.