PHYSICS LETTERS B, vol.424, pp.202-212, 1998 (SCI-Expanded)
CHORUS is an experiment searching for nu(mu) --> nu(tau) oscillation in the CERN wide band neutrino beam with a hybrid setup consisting of a nuclear emulsion target followed by electronic detectors. The experiment has been taking data from 1994 through 1997. A subset of the neutrino interactions collected in 1994 and 1995 have been analyzed, looking for nu(tau) charged current interactions where the tau lepton decays to mu<(nu)over bar>(mu)nu(tau). In a sample of 31,423 nu(mu) charged current interactions, no nu(tau) candidates were found. For large Delta m(mu tau)(2) values, a limit on the mixing angle of sin(2)2 theta(mu tau) < 3.5 x 10(-3) at 90% C.L. can be set, thus improving the previous best result. (C) 1998 Elsevier Science B.V.