Karmen: Present Neutrino-Oscillation Limits and Perspectives after the Upgrade

Abstract

The neutrino experiment KARMEN is situated at the beam stop neutrino source ISIS. It provides v _μ ’s, v _e ’s and ${\bar v_\mu }'s$ in equal intensities from the${\pi ^ + } - {\mu ^ + }$ decay at rest. The oscillation channels$v\mu \to {v_e}$ and${\bar v_\mu } \to {\bar v_e}$ are investigated with a 56 t liquid scintillation calorimeter at a mean distance of 17.6 m from the v− source. No evidence for oscillations could be found with KARMEN, resulting in 90% CL exclusion limits of ${\sin ^2}(2\theta ) < 8.5\cdot{10^{ - 3}}({\bar v_\mu } \to {\bar v_e})$ and ${\sin ^2}(2\theta ) < 4.0 \cdot {10^{ - 2}}({v_\mu } \to {v_e})$ for $\Delta {m^2} > 100e{V^2}$.

for the KARMEN Collaboration