The CLEO II detector includes a silicon vertex detector (SVX) and a small wire chamber concentric about the beam pipe. The outer vertex detector (VD) is a drift chamber similar to the outer drift chamber, with an inner radius of 8.1 cm and an outer radius of 16.4 cm. It contains 10 axial rings of wires at high voltage, surrounded by field wires in a hexagonal pattern, for a total of 800 high voltage "sense" wires and 2272 field wires. The VD also has segmented cathode layers at the inner and outer diameters of the chamber to provide measurements of position along the length of the detector, as shown here:
Inside the inner diameter of the SVX is the CESR beam pipe.