VXD3: The SLD vertex detector upgrade

The SLD Collaboration is building a new CCD vertex detector (VXD3) comprising 96 3.2 Mpixel CCDS of 13 cm2 each for a total of 307 million pixels.This system is an upgrade of the pioneering CCD vertex detector VXD2.which has operated in SLD since 1992.The CCDS of VXD3 are mounted on beryllium ladders in three cylinders, providing three space point measurements along each track of about 5 microns resolution in all three coordinates.The design and construction of VXD3 builds on three years of successful performance of VXD2.Significant improvements are achieved with VXD3 in impact parameter resolution (about a factor of two) and acceptance (-20Yo) through optimized geometry and reduced material.New readout electronics have been developed for this system This new vertex detector will be installed in late 1995 for the future runs of SLD.