The straw-tube tracker of the ZEUS-detector at HERA

The design of the straw tube tracker (STT) is described. The detector consists of 48 sectors and an overall of 11,000 straws, which allows precise track measurements in the forward direction of the ZEUS-detector at HERA. Test beam measurements are shown and the results are compared to Monte Carlo simulations. The STT is also used in the ZEUS trigger logic. An offline reconstruction algorithm is implemented and works. It is shown that we are able to reconstruct tracks in the forward direction of ZEUS, up to a pseudorapidity of 3.2 with high efficiency.