KLEVER: An experiment to measure BR(KL→π0ννˉK_L\to\pi^0\nu\bar{\nu}) at the CERN SPS

Precise measurements of the branching ratios for the flavor-changing neutral current decays $K\to\pi\nu\bar{\nu}$ can provide unique constraints on CKM unitarity and, potentially, evidence for new physics. It is important to measure both decay modes, $K^+\to\pi^+\nu\bar{\nu}$ and $K_L\to\pi^0\nu\bar{\nu}$, since different new physics models affect the rates for each channel differently. The goal of the NA62 experiment at the CERN SPS is to measure the BR for the charged channel to within 10%. For the neutral channel, the BR has never been measured. We are designing the KLEVER experiment to measure BR($K_L\to\pi^0\nu\bar{\nu}$) to $\sim$20% using a high-energy neutral beam at the CERN SPS starting in LHC Run 4. The boost from the high-energy beam facilitates the rejection of background channels such as $K_L\to\pi^0\pi^0$ by detection of the additional photons in the final state. On the other hand, the layout poses particular challenges for the design of the small-angle vetoes, which must reject photons from $K_L$ decays escaping through the beam exit amidst an intense background from soft photons and neutrons in the beam. Background from $\Lambda \to n\pi^0$ decays in the beam must also be kept under control. We present findings from our design studies for the beamline and experiment, with an emphasis on the challenges faced and the potential sensitivity for the measurement of BR($K_L\to\pi^0\nu\bar{\nu}$).Comment: 13 pages, 4 figures. Submitted as input to the 2020 update of the European Strategy for Particle Physics. v2: Included authors unintentionally omitted in v

The RPC system of the OPERA experiment

none27The OPERA experiment is designed to study the v(mu) -> v(tau) oscillation observing the v(tau) appearance in a pure v(mu) beam over a base line of 732 km from CERN to Gran Sasso Laboratory. The apparatus consists of a lead/emulsion-film target complemented by electronic detectors and muon spectrometers for muon charge and momentum measurements. The tracking inside the magnets is provide by Bakelite RPC chambers in a large scale application. The commissioning of the RPC system ended in August 2006. The paper present the layout of the RPC system and its performances. (C) 2009 Elsevier B.V. All rights reserved.noneA. Bertolin;R. Brugnera;A. Candela;E. Cararra;L. Castellani;A. Cazes;G. Corradi;F. D. Corso;M. D'Incecco;A. D. Giovanni;S. Dusini;G. Felici;A. Garfagnini;C. Gustavino;A. Lindozzi;I. Lippi;A. Longhin;A. Mengucci;A. Paoloni;G. Papalino;M. Spinetti;L. Stanco;M. Stipcevic;V. Sugoniaev;F. Terranova;M. Ventura;L. VotanoBertolin, A.; Brugnera, Riccardo; Candela, A.; Cararra, E.; Castellani, L.; Cazes, A.; Corradi, G.; Corso, F. D.; D'Incecco, M.; Giovanni, A. D.; Dusini, S.; Felici, G.; Garfagnini, Alberto; Gustavino, C.; Lindozzi, A.; Lippi, I.; Longhin, A.; Mengucci, A.; Paoloni, A.; Papalino, G.; Spinetti, M.; Stanco, L.; Stipcevic, M.; Sugoniaev, V.; Terranova, F.; Ventura, M.; Votano, L