Construction and performance of the new ALEPH vertex detector

University of Glasgow
Max Planck Institut für Physik (Werner-Heisenberg-Institut)
Sezione di Bari Istituto Nazionale di Fisica Nucleare
Santa Cruz Institute for Particle Physics
University of Wisconsin Madison
Scuola Normale Superiore di Pisa
Lancaster University
Rutherford Appleton Laboratory
Università degli Studi di Firenze
European Organization for Nuclear Research
Université de la Méditerranée Aix-Marseille II
Università degli Studi di Trieste
Seattle University of Washington
Imperial College London

Abstract

A new Silicon Vertex Detector was developed for the ALEPH experiment and first installed for the high energy run at 130 GeV at the end of 1995. The detector has an active length of 40 cm and consists of two concentric layers of silicon wafers with double-sided readout. It extends the angular coverage, has only half the passive material as the former detector in the tracking volume and is radiation hard to cope with the higher level of radiation background expected for the LEP2 phase. The construction and the performance of the detector is described.