KARMEN at ISIS: The advantage of a pulsed neutrino source in the search for neutrino oscillations and neutrino nuclear interactions

Abstract KARMEN, the Karlsruhe-Rutherford Medium Energy Neutrinoexperiment at the pulsed spallation neutron facility ISIS uses the beam stop neutrinos ν μ , ν e and ν μ from π + and μ + decay at rest to search for neutrino oscillations in the appearance channels ν μ → ν e and ν μ → ν e . The signature for both oscillations is based on charged current neutrino nuclear interaction spectroscopy in a high resolution 56 t liquid scintillator calorimeter. The detector system has been upgraded with an additional veto layer during 1996 to eliminate cosmogenic background and to enhance its sensitivity in the oscillation channels. This report describes the results based on data acquired from June 1990 to August 1995 and the first data of 1997 with the new veto system in operation.