The TASSO High Precision Vertex Detector Project

Drift chambers of various types have now been in use in large colliding beam detectors for many years. Typical spatial resolutions of these detectors have been around 200 micrometers. However, the theoretical limitation on the resolution attainable due to the statistical nature of the ionization process and diffusion of the electrons prior to collection is much smaller than this. Using high pressure organic gases, resolutions of better than 40 micrometers have been achieved. Both MARK II and then TASSO have proposed the construction of drift chambers close to the interaction point in e(+)e(-) colliding beam machines. The MARK II vertex detector is already installed at PEP.This paper discusses the status of the TASSO high precision vertex detector project, together with a brief description of its physics aims.