Measurement Results with the BEXE Detector at LEP

Two detectors based on fast CdTe photoconductors are installed in LEP for the measurement of the vertical beam profiles and for an observation of the bunch length via autocorrelation. Due to the fast response time of these detectors the beams can be observed turn by turn. With a fast gating (10ns) of the polarisation voltage of the detectors even single bunches of LEP bunch trains can be selected for measurements. The paper gives typical measurement examples and describes the calibration procedure. Special emphasis is given on the use of the vertical profile monitors as real time display in the LEP control room.