Recent results and running experience of the new ALEPH Vertex Detector

A description of the ALEPH Vertex Detector (VDET 91), including the mechanical structure and the improved data acquisition system, is given. The apparatus consists of two complete layers of silicon detectors with double-sided readout which provide a full x, y, z information of the impact points of charged particles. The authors show results on signal-to-noise ratio for minimum ionizing particles and efficiency in hit/track matching. Results on position, impact parameter, and momentum resolution are also shown as measured using high momentum muons. The first preliminary study on vertexing techniques and their impact on physics analysis is discussed.<
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