A Silicon Microstrip Detector for COMPASS and a First Measurement of the Transverse Polarization of Lambda-Hyperons from Quasi-Real Photo-Production

A new Silicon microstrip detector was developed for the COMPASS experiment at the CERN / SPS. The detector was installed in the year 2002 and successfully operated. It provides a space resolution down to 10 µm and a time resolution of the order of 3 ns. In order to increase its radiation tolerance, it was designed to be operated at a temperature of 130 K. In the second part a first measurement of the transverse polarization of Lambda hyperons from quasi-real photo-production in the COMPASS experiment was performed. Averaged over the full kinematics a positive polarization of 4.4 +/- 0.8 (stat.) +/- 0.5 (sys.) % was found. In the target fragmentation region the behaviour of the hyperon polarization was found to be similar to the case of meson-production.