Bochum 1998 – wissenschaftliches Programm

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HK: Hadronen und Kerne

HK 29: Weak Interactions and Fundamental Symmetries II

HK 29.4: Gruppenbericht

Dienstag, 17. März 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 ν_µ’s, ν_e’s and ν_µ’s in equal intensities from the π⁺–µ⁺ decay chain at rest. The oscillation channels ν_µ→ ν_e and ν_µ→ ν_e (appearance) as well as ν_e→ ν_x (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 ( ν_e , e⁻ ) ¹²N_g.s. and p ( ν_e , 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 ν_µ→ ν_e 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 ν_µ→ ν_e oscillations given by the LSND experiment.