Fertigung und Inbetriebnahme einer Strohdriftkammerstation für das COMPASS-Experiment

The so-called ”COMPASS” spectrometer recently put into operation at the European Laboratory for Particle Physics (C.E.R.N.) uses straw drifttubes as space sensitive detectors for tracking purposes. The presented work deals with the specification of these detectors and monitors construction and commissioning up to the investigation of their properties using a testbeam, as well as the installation into the spectrometer. It could be shown that the detectors meet the requirements of the experimental program the COMPASS spectrometer aims for, in particular determined by the necessity of an efficient detection of the D0-meson decay D0 ! K¡p+: Between the first spectrometer magnet and the ring-imaging Cherenkov counter the setup requires a system for the determination of charged-particle tracks. On one hand it has to be compact in the beam direction, on the other it must offer a high time and spatial resolution while covering the relatively large solid angle given by the aperture of the target magnet which amounts to 180 mrad. Due to this the active surface at the foreseen location will be around 10 m2. The geometrical precision reached during production determines the precision of the information obtained on track coordinates of the decay products and thus - having an impact on the measurement of energies and momenta of the reaction products - influences the precision of the D0-meson mass measurement. Observing rare processes li ke the one mentioned above with high accuracy means collecting a huge sample of decay events, making it necessary to expose the detectors to high particle fluxes. Thus, particular attention was paid to the experiments concerning spatial resolution and detection efficiency, but also to the aging behaviour. The counters were manufactured at the Joint Institute for Nuclear Research (JINR) at Dubna (Russian Federation), which means that the production was also challenging in terms of logistics. Where necessary not only the production technology but also details concerning the work organization and materials flow are described.