Search for. nu. /sub. mu. /. --> nu. /sub e/ oscillations

We present the results of a search for neutrino oscillations conducted at Brookhaven National Laboratory. The experiment searched for the appearance of ..nu../sub e/ 1 km from the source of a 1.4-GeV (mean energy) narrow-band ..nu../sub ..mu../ beam. With 3 x 10/sup 19/ protons on target from the Alternating Gradient Synchrotron, no excess of ..nu../sub e/ was detected. The 90% confidence limits obtained are ..delta..m/sup 2/less than or equal to0.10 eV/sup 2/ for maximal mixing, and sin/sup 2/2thetaless than or equal to0.016 for large ..delta..m/sup 2/.