Search

The NA48/2 collaboration has analysed more than one million K ± → π + π − e ± ν decays, resulting in the improved determination of branching fraction by a factor of 3 and high precision form factor measurements. Concurrently, about 45000 K ± → π 0 π 0 e ± ν decays have been analyzed. Background contamination below the percent level and very good π 0 reconstruction allow the first accurate measurement of the branching fraction and decay form factor at the percent level. The achieved precision makes possible the observation of small effects such as π + π − → π 0 π 0 re-scattering. Both K e 4 modes decay properties bring new precise inputs to Low Energy QCD studies and can provide strong tests of ChPT predictions. Future prospects include the observation of several thousand decays in similar muonic modes K ± → π 0 π 0 μ ± ν and K ± → π + π − μ ± ν , that could be studied also in the forthcoming NA62 experiment.

The ultra-rare decays K → π ν ν ¯ are excellent processes to make tests of new physics at the highest energy scale complementary to LHC, thanks to their theoretically clean predictions. The NA62 experiment at the CERN SPS aims to collect about 100 K + → π ′ ν ν ¯ events in two years of data taking, keeping the background at 10% level. A rich physics program is accessible to NA62, in addition to the main goal. A precise measurement of the helicity-suppressed ratio R K of the K ± → e v e and K ± → μ v μ decay rates has already been performed, using data collected at an early stage of the experiment. The result agrees with the Standard Model expectations. A description of the R K measurement, the physics prospects and the status of the NA62 experiment will be presented in this paper.

The NA62 experiment, which aims to measure the branching ratio of the very rare kaon decay K + → π + ν ν ¯ at the CERN SPS, is described. The proposed experiment aims to collect some 100 K + → π + ν ν ¯ events with a 10% of background. The status and the future perspectives for the experiment are discussed.

The NA62 experiment at CERN aims at measuring the ultra-rare decay K + → π + ν ν ¯ with a 10% accuracy; the main background is K + → μ + ν which is suppressed by means of kinematical cuts and by the different stopping power of μ + and π + . A further 0.5 % μ + suppression must be provided by a RICH detector in a momentum range between 15 and 35 GeV/c. In this paper a RICH filled with Neon at atmospheric pressure contained in a 17 m long, 3 m wide vessel and in which the Cherenkov light is readout by 2000 single-anode photomultipliers, will be described. The results of a test beam performed with a prototype will be presented.

The RICH detector of the NA62 experiment is proposed for pion - muon separation and to contribute to the first level of the trigger. The design parameters of the detector and the results of test beams performed at CERN in 2007 and 2009 with a prototype are presented., Comment: 3 pages, 2 figures, To appear in the proceedings of 12th Topical Seminar on Innovative Particle and Radiation Detectors (IPRD10), Siena, Italy, 7-10 June 2010