Results from the karmen υ-oscillation search

The neutrino experiment KARMEN is situated at the beam dump neutrino source ISIS. Its 100 ns wide double proton pulses procedure νμ'S, νe'S and ν-barμ'S in equal intensities from the π+-μ+ decay at rest. νe'S are not produced in the ISIS source apart from a small contamination. The oscillation channels νμ → νe and ν-barμ→ν-bare (in the appearance mode) as well as ν-bare→nu-barx (in the disappearance mode) are investigated with a 56 t liquid scintillation calorimeter at a mean distance of 17.6 m from the ν-source. The detection reactions are 12C(νe,e-) 12Ng.s. for νμ→νe and νe→νx) and p(ν-bare, e+)n (for ν-barμ→ ν-bar) in appropriate time and energy ranges. The analysis of the experiment data from 1990 to 1995 takes full advantage of the well known energy spectra of the neutrinos, the spectroscopic qualities of the detector as well as the unique time structure of the ISIS pulsed ν-source. No evidence for oscillations could not be found with KARMEN, resulting in 90 % CL exclusion limits for sin2(2Θ)< 7.5 x 103 (ν-barμ→ν-barμ→ν-bare and sin2(2Θ) < 3.8 x 10-2 (νμ→νe) for large Θm2. To increase the sensitivity for νμ->ν-bare down to sin2(2Θ) 103 an additional veto counter system is actually being built. (author)