Neutrino oscillation results from KARMEN

Abstract

The neutrino experiment KARMEN is situated at the beam stop neutrino source ISIS. It provides ν μ 's, ν e 's and ν μ' s in equal intensities from the π +- μ +-decay at rest (DAR). The oscillation channels ν μ → ν e and ν μ → ν e are investigated in the appearance mode with a 56t liquid scintillation calorimeter at a mean distance of 17.7m from the ν-source. Analyses of experimental data from the measuring period 1990–1995 corresponding to 9122 C protons on target or 2.52 · 10 21 μ + DAR are presented. No evidence for oscillations could be found with KARMEN, resulting in 90% CL exclusion limits of sin 2(2θ) < 8.5·10 −3 ( ν μ → ν e) and sin 2(2 θ) < 4.0·10 −2 ( ν μ → ν e ) for Δm 2 ≥ 100 eV 2 in a simple 2 flavor description of ν-oscillations.