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 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.

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The NA48 collaboration is preparing a new experiment at CERN aiming to study CP violation in the K-0-(K-0) over bar system with an accuracy of 2 x 10(-4) in the parameter Re(epsilon'/epsilon). Decays in two pi(0)'s will be recorded by a quasi-homogeneous liquid krypton calorimeter. A liquid krypton calorimeter has been chosen to combine good energy, position and time resolution with precise charge calibration and long-term stability. The prototype calorimeter incorporating the final design of the electrode read-out structure is presented in this paper. An energy resolution of similar or equal to 3.5%/root E with a constant term smaller than 0.5% has been obtained. The time resolution was found to be better than 300 ps above 15 GeV

The 13 500 channels of the NA48 liquid-krypton electromagnetic calorimeter readout electronics were put into operation in 1997. The digitizer electronics employs a new gain switching technique that expands the dynamic range of a standard 10-bit ADC to 14 bits at 40 MHz sampling rate employing a custom-developed integrated circuit (KRYPTON). The KRYPTON has been fabricated in 1.2 µm BiCMOS technology and was successfully developed together with industry on a short timescale. The performance and the experience from the first year of the operation of the liquid-krypton calorimeter electronics will also be briefly discussed.