CERN Neutrinos to Gran Sasso (CNGS): First Beam

The CNGS, CERN Neutrinos to Gran Sasso, project aims at directly detecting nu_mu-nu_tau neutrino oscillations. An intense muon-neutrino beam (10¹⁷ nu_mu/day) is generated at CERN and directed towards the Gran Sasso National Laboratory, LNGS, in Italy, 732 km away from CERN. In LNGS large and complex detectors will allow to detect, in particular, the rare tau-neutrinos created by ´oscillation´ from muon-neutrinos on their way between CERN and LNGS. On average around three tau-neutrino events are predicted per year in each of the ~2000 ton detectors. The construction of the CNGS beam facility started in September 2000, and the first neutrino beam has been produced in July 2006. In the presently approved physics programme, it is foreseen to run the facility for five years.