The central-inner z-drift chamber of the H1 experiment

We discuss a novel wire arrangement, z-drift chamber for the H1 experiment at HERA (DESY). The chamber consists of fifteen 12 cm long rings along the z-axis, each of which is a regular sixteenfold polygon in cross section. There are four sense and three guard wires per ring, and these wires lie in a plane tilted 45deg from the normal. The chamber will measure accurate z-information for polar angles θ between 20deg and 170deg. Using the tilted-wire arrangement and a sophisticated drift-time-to-position conversion we have achieved a resolution of about 320 μm which is virtually independent of the crossing angle. (orig.)