Abstract: | The CHORUS experiment is designed to search for νμ → ντ oscillation with a hybrid detector system containing 800 kg nuclear emulsions as target and vertex detector. Run I (320 000 recorded νμCC in 1994/5) and more than half of the run II (460 000 νμCC in 1996/7) data taking have been successfully completed. Approximately 80 000 events have been analyzed so far, searching for and τ− → h− (nπ0) ντ decays. No candidate has been found, leading to a limit sin2 2θμτ ≤ 4.5 10−3 for large Δm2. |