First Results from φ → K L K S Decays with the KLOE Detector

The KLOE experiment has collected 2.4 pb of integrated luminosity during the commissioning of the DAΦNE φ-factory in 1999. The performance of the detector has been studied using the φ → KLKS decays collected during this period, yielding also first measurements of relevant K parameters such as masses and lifetimes. A clean KS → π π sample is used to select KL → ππ CP-violating decays and KL → KS regeneration events in the detector material. Results on the regeneration probability in a beryllium-alluminum alloy and carbon-fiber plus aluminum composite are presented. Contributed paper ♯ 294 to the XXX International Conference on High Energy Physics, Osaka 27 jul 2 aug 2000.