The phenomenon of neutrino oscillations was studied with the use of the muon neutrino beam generated by the proton synchrotron (AGS) at Brookhaven National Laboratory, operated at 28.3 GeV/c. The analysis is conducted on the totality of accumulated interactions with at least one electromagnetic shower in the final state and leads to the observation of 38.5 ± 14.4 (stat) ± 10.2 (syst) excess events attributed to electron neutrino interactions. The excess is at the level of 2.7 ± 0.7 standard deviations. If this result is interpreted as neutrino oscillations then in the sin\sp22\theta- \delta m\sp2 plane of oscillations for the v\sb\mu\to v\sb{e} channel it allows values of \delta m\sp2 between 1 and 10 eV\sp2 and 1% for sin\sp22\theta. Other interpretations are also possible.Ph.D.High energy physicsPure SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/128315/2/8920515.pd