Fertigung und Inbetriebnahme einer Stroh-Driftkammerstation 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- pi+: 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 m^2. 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 like 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.