Performance and Operational Experience of the CNGS Facility

The CNGS facility (CERN Neutrinos to Gran Sasso) aims at directly detecting muon to tau neutrino oscillations. An intense muon-neutrino beam (1.0•1017 muon neutrinos/day) is generated at CERN and directed over 732km towards the Gran Sasso National Laboratory, LNGS, in Italy, where two large and complex detectors, OPERA and ICARUS, are located. CNGS is the first long-baseline neutrino facility in which the measurement of the oscillation parameters is performed by observation of the tau-neutrino appearance. The facility is approved for a physics program of five years with a total of 22.5•1019 protons on target. Having resolved successfully some initial issues that occurred since its commissioning in 2006, the facility had its first complete year of physics in 2008. By the end of 2009 the facility delivered in total 5.4•1019 protons on target corresponding to an expected ~2-3 tau neutrino events in the OPERA detector, according to the most probable physics parameter oscillation model of today. The experiences gained in operating this 500 kW neutrino beam facility along with highlights of the beam performance in 2009 are discussed.