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Charged current reactions of nu_e on 12C have been studied using a mu decay-at-rest nu_e beam from the Los Alamos Meson Physics Facility. More than 500 events from the exclusive reaction 12C + nu_e -> e- + 12N g.s. were measured in a large Liquid Scintillator Neutrino Detector (LSND). The observed energy dependence of the cross section and the angular distribution of the outgoing electron agree well with theoretical expectations. Measurements are also presented for inclusive transitions to 12N excited states, 12C + nu_e -> e- + 12N and compared with theoretical expectations. Results are consistent with a recent Continuum Random Phase Approximation (CRPA) calculation.

A search for ${\overline{\ensuremath{\nu}}}_{e}$'s in excess of the number expected from conventional sources has been made using the Liquid Scintillator Neutrino Detector, located 30 m behind the Los Alamos Meson Physics Facility beam stop. The ${\overline{\ensuremath{\nu}}}_{e}$ are detected via ${\overline{\ensuremath{\nu}}}_{e}p\ensuremath{\rightarrow}{e}^{+}n$ with ${e}^{+}$ energy between 36 and $60\mathrm{MeV}$, followed by a $\ensuremath{\gamma}$ ray from $\mathrm{np}\ensuremath{\rightarrow}d\ensuremath{\gamma}$ ( $2.2\mathrm{MeV}$). Using strict cuts to identify $\ensuremath{\gamma}$ rays correlated with ${e}^{+}$ yields 9 events with only $2.1\ifmmode\pm\else\textpm\fi{}0.3$ background expected. A likelihood fit to the entire ${e}^{+}$ sample results in a total excess of ${16.4}_{\ensuremath{-}8.9}^{+9.7}\ifmmode\pm\else\textpm\fi{}3.3$ events. If attributed to ${\overline{\ensuremath{\nu}}}_{\ensuremath{\mu}}\ensuremath{\rightarrow}{\overline{\ensuremath{\nu}}}_{e}$ oscillations, this corresponds to an oscillation probability of ( ${0.34}_{\ensuremath{-}0.18}^{+0.20}\ifmmode\pm\else\textpm\fi{}0.07$)%.

A search for neutrino oscillations of the type nu_bar_mu to nu_bar_e has been conducted at the Los Alamos Meson Physics Facility using nu_bar_mu from muon decay at rest. Evidence for this transition has been reported previously. This paper discusses in detail the experimental setup, detector operation and neutrino source, including aspects relevant to oscillation searches in the muon decay-at-rest and pion decay in flight channels., 27 pages, 26 figures, revtex and psfig, additional information available at http://nu1.lampf.lanl.gov/~lsnd/