A light straw tracker detector working in vacuum

We are developing a straw tracking system with 3000 straws to work under vacuum conditions. The inactive parts of the detector-like frames, gas system and electronics, etc. have an extremely small mass density to reduce straggling of charged particles which will be detected in further surrounding detectors like the TOF-experiment at COSY. We avoid a massive frame by running the straw tubes with an excess pressure of 1 bar. The mechanical properties and the excess pressure create the necessary wire tension and the stability of the straw tubes which have a wall thickness of 30 μm Mylar. In this paper, we present our new detector concept and discuss results of the first prototype tests.