No Arabic abstract
After a long preparatory phase, including a wide hardware consolidation program, the Italian lepton collider DAFNE, is now systematically delivering data to the KLOE-2 experiment. In approximately 200 days of operation 1 fb-1 has been given to the detector limiting the background to a level compatible with an efficient data acquisition. Instantaneous and maximum daily integrated luminosity measured, so far, are considerably higher with respect to the previous KLOE runs, and are: L(inst) ~ 2.0 1032 cm-2s-1, and L(day) ~ 12.5 pb-1 respectively. A general review concerning refurbishing activities, machine optimization efforts and data taking performances is presented and discussed.
DAFNE operation restarted in September 2003, after a six month shut-down for the installation of FINUDA, a magnetic detector dedicated to the study of hypernuclear physics. FINUDA is the third experiment running on DAFNE and operates while keeping on place the other detector KLOE. During the shut-down both Interaction Regions have been equipped with remotely controlled quadrupoles in order to operate at different solenoid fields. Among many other hardware upgrades one of the most significant is the reshaping of the wiggler pole profile to improve the field quality and the machine dynamic aperture. Commissioning of the collider in the new configuration has been completed in short time. The peak luminosity delivered to FINUDA has reached 6 10^31 s-1cm-2, with a daily integrated value close to 4 pb-1.
The DAFNE collider, located in the Frascati National Laboratories of INFN, has two main rings, where electrons and positrons are stored to collide at a center of mass energy of 1.02 GeV, the phi resonance mass. KLOE-2 experiment is located at the collider interaction region. The detector is capable to observe and collect data coming from phi decay: charged and neutral kaon pairs, lighter unflavored mesons (eta, eta, f0, a0, omega/rho). In the first half of 2013 the KLOE detector has been upgraded inserting new detector layers in the inner part of the apparatus, around the interaction region in order to improve detector hermeticity and acceptance. The long shutdown has been used to undertake a general consolidation program aimed at improving the DAFNE performances. This contribution presents the phi-factory setup and the achieved performances in terms of beam currents, luminosity and related aspects together with the KLOE-2 physics program, upgrade status report and recent physics results.
The KLOE-2 experiment at the INFN Laboratori Nazionali di Frascati (LNF) is currently taking data at the upgraded $e^{+}e^{-}$ DAFNE collider. Present Run II follows a~development phase to assess the feasibility of a long term acquisition program, Run I, which successfully ended in July 2015 with 1 fb$^{-1}$ integrated luminosity collected in less than eight months. KLOE-2 represents the continuation of the KLOE experiment with a new physics program. The KLOE detector has undergone several upgrades including state-of-the-art cylindrical GEM Inner Tracker, electron-positron taggers for the $gammagamma$-physics studies and new calorimeters around the interaction point. In this article we briefly present the overview of the KLOE-2 experiment including the present status and achievements together with the physics plans.
We present results of a direct search for the decay KS --> e+e- with the KLOE detector, obtained with a sample of e+e- --> phi --> KSKL events produced at DAFNE, the Frascati phi-factory, for an integrated luminosity of 1.3fb-1. The Standard Model prediction for this decay is BR(KS --> e+e-) = 1.6*10^-15. The search has been performed tagging the KS decays by simultaneous detection of a KL interaction in the calorimeter. Background rejection has been optimized by using both kinematic cuts and particle identification. At the end of the analysis chain we find BR(KS --> e+e-) < 2.1*10^-8 at 90% CL, which improves by a factor of ~7 on the previous best result, obtained by CPLEAR experiment.
The results of 2002 DAFNE operation for the two experiments KLOE and DEAR are described. During 2003 a long shutdown has been dedicated to the installation of new Interaction Regions (IR) and to hardware modifications and upgrades. In the last section optics studies and performances expectations for the new machine configuration are reported.