Performance of prototypes of the H1 outer z-drift chamber

Test measurements were performed with prototypes (full-scale radius and single cells) of the outer z-drift chamber (COZ) of the central tracker of the HERA experiment H1. The COZ consists of a 2.20 m long cylindrical arrangement of rectangular drift cells made of 24 identical rings of 47 cm radius with sense wires strung in a 24-fold polygon around the beam axis. The signals are transmitted via flexible twin lines to the preamplifiers located outside the gas volume at the end flanges. The tests were performed at a DESY test beam using Ar/CH4 and Ar/C3H8 and a 100 MHz FADC readout. Detailed results on the geometric efficiency, resolution and charge division are reported.