Update on neutrino oscillation search with KARMEN

Abstract

KARMEN, the Karlsruhe- Rutherford Medium Energy Neutrinoexperiment at the pulsed spallation neutron facility ISIS uses beam stop neutrinos ν μ, ν e and ν ̄ ν from π + and π + decay at rest to search for neutrino oscillations in the appearance channels ν μ → ν e and ν μ → ν e and in the disappearance channel ν e → ν x. The signature for the oscillations is based on charged current neutrino nuclear interaction spectroscopy in a high resolution 56t liquid scintillator calorimeter. This update on KARMEN oscillation results covers the new period of data acquisition (KARMEN 2) from February 1997 to February 1999 with the additional veto system installed in 1996 in operation. KARMEN 2 shows no evidence for neutrino oscillations and excludes an even larger region of the LSND ν μ → ν e oscillation parameter space than KARMEN 1.