The NA48 liquid-krypton calorimeter

The NA48 experiment at CERN was primarily designed to measure the value of Re(ε′/ε), the parameter of direct CP-violation, from two-pion decays in simultaneous KL0 and KS0 beams produced at two different targets. Data for this measurement were taken from 1997 to 2001. The value obtained from the data taken in 1997–1999 is Re(ε′/ε)=(15.3±2.6)×10−4 (Eur. Phys. J. 22 (2001) 231). The remaining data are being analyzed at present. 2 and the following years, rare-decay and CP-violation studies will be made in a high-intensity KS0 beam (CERN/SPSC 2000-002) and in simultaneous beams of charged kaons (CERN/SPSC 2000-003), using basically the same apparatus. s from neutral-pion decays are detected by a liquid-krypton calorimeter. For the Re(ε′/ε) measurement it is very important to suppress the huge background from KL0→3π0 decays, which requires very good spatial, energy and time resolution.