The LHCb experiment is dedicated to precision measurements of CP violation and rare decays of B hadrons at the Large Hadron Collider (LHC) at CERN (Geneva). The initial configuration and expected performance of the detector and associated systems, as established by test beam measurements and simulation studies, is described.

The beam and detector, used for the NA48 experiment, devoted to the measurement of Re(epsilon'/epsilon) and for the NA48/1 experiment on rare KS and neutral hyperon decays, are described

The CPLEAR collaboration has constructed a detector at CERN for an extensive programme of CP-, T-and CPT-symmetry studies using K and K 0 produced by the annihilation of p's in a hydrogen gas target. The K 0 and K 0 are identi ed by their companion products of the annihilation K which are tracked with multiwire proportional chambers, drift chambers and streamer tubes. Particle identi cation is carried out with a liquid Cherenkov detector for fast separation of pions and kaons and with scintillators which a l l o w the measurement o f t i m e o f i g h t and energy loss. Photons are measured with a lead/gas sampling electromagnetic calorimeter. The required antiproton annihilation modes are selected by fast online processors using the tracking chamber and particle identi cation information. All the detectors are mounted in a 0.44 T uniform eld of an axial solenoid of diameter 2 m and length 3.6 m to form a magnetic spectrometer capable of full online reconstruction and selection of events. The design, operating parameters and performance of the sub-detectors are described.

The NA48 experiment at the CERN SPS accelerator is making a measurement of thc direct CP violation paramctcr E I / C by compering thc four rates of decay of IQ and K, . into 2x0 and K + K -. To reconstruct the dccliys into 2x0 the information from the almost 13500 channels of ii qiiasi-hornogeneous liquid krypton elcctromagnetic calorimeter is used. The readout electronics of the calorimeter has been designed to provide a dynamic range from a Cew McV to about 50 GeV eiiergy deposition per cell, and to sustain a high rate of incident particles. The system is made by cold charge preamplifiers (working at 120°K). low-noise fast shapers followed by digitizer electronics at 40 MHz sampling rate that employs a gain switching technique to expand the dyilainic range, where the gain can bc selected for each sample individually (i.e. cvery 25 ns). To reduce the amount of data cullected the system contains a zero suppression circuit based on halo cxpaosion.

A new apparatus for detection of ! oscillation has been successfully constructed and operated by the CHORUS Collaboration for the CERN-WA95 experiment. The design, implementation and performance of the electronic trigger system is described. A trigger eciency of 99% was measured for charged current events and 90% for neutral current events.