The design and construction of the large Drift Chamber for the KLOE experiment at the Frascati φ-factory, DAΦNE, are described. The relevant aspects of the various elements of the detector are reviewed together with a description of the track reconstruction program and of the calibration procedures. The performance of the detector based on measurements with cosmic rays and with e+e− colliding beams during DAΦNE commissioning is presented.

A double-level trigger system has been developed for the KLOE experiment. Custom electronics asserts a trigger in a 2μs decision time. The decision is based on the combined information of the electromagnetic calorimeter and the drift chamber. The entire trigger system is continuously monitored, and data flowing from the trigger system have allowed both an efficient online monitoring of the detector and an online luminosity measurement.

The main aim of the KLOE experiment at DAΦNE, the Frascati φ-factory, is to study CP violation in the K0–K̄0 system. Requirements on shower detection are very stringent. An hermetic, lead-scintillating fiber sampling calorimeter has been chosen and built. A review of the methods used to calibrate and reconstruct energy and timing is reported in this paper. Emphasis is given to the calibration procedures developed using the 2.4 pb−1 collected in 1999. An energy resolution of 5.7%/E/GeV is achieved together with a linearity in energy response better than 1% above 50 MeV. A time resolution of ∼54 ps/E/GeV is also measured on samples of radiative Bhabha and Φ decays.

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.

The status of the KLOE detector at the Frascati phi -factory DA Phi NE and preliminary results obtained with the data collected in 1999 (similar to 2.4pb(-1), corresponding to about 7 millions phi) are presented.

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.