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HK: Hadronen und Kerne
HK 29: Weak Interactions and Fundamental Symmetries II
HK 29.4: Group Report
Tuesday, March 17, 1998, 15:00–15:30, E
Search for Neutrino Oscillations with KARMEN — •K. Eitel — Forschungszentrum und Universität Karlsruhe
The neutrino experiment KARMEN is situated at the beam stop neutrino source ISIS. It provides νµ’s, νe’s and νµ’s in equal intensities from the π+–µ+ decay chain at rest. The oscillation channels νµ→ νe and νµ→ νe (appearance) as well as νe→ νx (disappearance) are investigated with a 56 t liquid scintillation calorimeter at a mean distance of 17.7 m from the ν–source via the inverse β–decay reactions 12C ( νe , e− ) 12Ng.s. and p ( νe , e+ ) n . The unique time structure of ISIS together with the good energy and time resolution of the KARMEN calorimeter ensures a clear identification of ν–induced events. Furthermore, a new additional veto system of 300 m2 surface within the 7000 t massive iron shielding of the main detector was installed in 1996 to suppress the cosmic induced background by a factor of 40. This upgrade increased substantially the sensitivity of the oscillation search which will reach sin2(2Θ ) ≃ 1 · 10−3 for large Δ m2 in the νµ→ νe channel after 3 years of measuring time.
Results of the first year with the upgraded experimental configuration (KARMEN2) will be presented and compared with the data from 1990–1995 (KARMEN1) as well as with the positive evidence for νµ→ νe oscillations given by the LSND experiment.