NEW EXPERIMENTAL LIMITS ON NU(E)-]NU(TAU) OSCILLATIONS IN 2-NU AND 3-NU MIXING SCHEMES

The 56 ton high resolution liquid scintillation calorimeter KARMEN at the beam stop neutrino source ISIS has been used to search for neutrin o oscillations in the disappearance channel nu(e)-nu(x). The nu(e) emi tted in mu(+) decay at rest are detected with spectroscopic quality vi a the exclusive charged current reaction C-12(nu(e),e(-))N-12(g.s.) al most free of background. Analysis of the spectral shape of e(-) from t he nu(e)-induced reaction as well as a measurement of the absolute nu( e) flux allows one to investigate oscillations of the type nu(e) --> n u(tau) and nu(e) --> nu(mu). The flux-independent ratio R-CC/NC of cha rged current events C-12(nu(e) , e(-))N-12(g.s.) to neutral current,ev ents C-12(nu,nu')C-12 provides additional information in the oscillat ion channel nu(e) --> v(tau). All three analysis methods show no evide nce for oscillations. For the nu(e) --> nu(tau) channel 90% confidence limits of sin(2)(2 Theta)<0.338 for Delta m(2) greater than or equal to 100 eV(2)/c(4) and Delta m(2)<0.77 eV(2)/c(4) for maximal mixing in a simple two-flavor oscillation formalism are derived. A complete thr ee-flavor analysis of the experimental data from 5 years of measuremen t with respect to nu(e) <-> nu(tau) nu <-> nu(mu) mixing is presented.