Measurement of Vertical Emittance at LEP from Hard X-Rays

Two solid state detectors measure in real time the vertical profiles of both beams in LEP, from hard X-rays produced in normal machine dipoles. Each detector consists of 64 elements of CdTe photoconductor deposited with a pitch of 100 pm on a ceramic support. Profiles can be recorded at the rate of bunch passages (88 kHz) for 250 revolutions and are subsequently analysed. This paper describes the new readout electronics adapted to 8 bunch operation of LEP and the performance of detectors using the data acquired in 1992. From the r.m.s. size of these profiles and the knowledge of machine optics, emittance values are obtained. >