  Test measurements on the silicon pixel detector for the beam trajectory
monitor at the free electron laser of the TESLA test facility are presented. To
determine the electronic noise of detector and read-out and to calibrate the
signal amplitude of different pixels the 6 keV photons of the manganese K line
are used. Two different methods determine the spatial accuracy of the detector:
In one setup a laser beam is focused to a straight line and moved across the
pixel structure. In the other the detector is scanned using a low-intensity
electron beam of an electron microscope. Both methods show that the symmetry
axis of the detector defines a straight line within 0.4 microns. The
sensitivity of the detector to low energy X-rays is measured using a vacuum
ultraviolet beam at the synchrotron light source HASYLAB. Additionally, the
electron microscope is used to study the radiation hardness of the detector.
