Differential cross sections for neutrino scattering on\({}_{}{}^{12}{}_{}{}^{}\mathrm{C}\)

A search for \(\nuebar\)'s in excess of the number expected from conventional sources has been made using the Liquid Scintillator Neutrino Detector, located 30 m from a proton beam dump at LAMPF. A \(\nuebar\) signal was detected via the reaction \(\nuebar\,p \rightarrow e^{+}\,n\) with \(e^+\) energy between 36 and \(60\mev\), followed by a \(\gamma\) from \(np\rightarrow d\gamma\) (\(2.2\mev\)). Using strict cuts to identify \(\gamma\)'s correlated with positrons results in a signal of 9 events, with an expected background of \(2.1 \pm 0.3\). A likelihood fit to the entire \(e^+\) sample yields a total excess of \(16.4^{+9.7}_{-8.9}\pm 3.3\) events, where the second uncertainty is systematic. If this excess is attributed to neutrino oscillations of the type \(\numubar\rightarrow\nuebar\), it corresponds to an oscillation probability of (\(0.34^{+0.20}_{-0.18}\pm 0.07\))\%.