First Results of νₑ Appearance Analysis and Electron Neutrino Identification at NOvA

الأصل · EN

NOvA is a long-baseline accelerator-based neutrino oscillation experiment that is optimized for νμ→νₑ measurements. It uses the upgraded NuMI beam from Fermilab and measures electron-neutrino appearance and muon-neutrino disappearance at its Far Detector in Ash River, Minnesota. The νₑ appearance analysis at NOvA aims to resolve the neutrino mass hierarchy problem and to constrain the CP-violating phase. The first data set of 2.74×10²⁰ protons on target (POT) equivalent exposure taken by NOvA has been analyzed. The first measurement of electron-neutrino appearance in NOvA provides solid evidence of νμ→νₑ oscillation with the NuMI beam line. Electron-neutrino identification is the key ingredient for the νₑ appearance analysis. The electron-identification algorithm used to produce the primary results presented here compares 3-D shower-energy profiles with Monte Carlo prototypes to construct likelihoods for each particle hypothesis. Particle likelihoods, among other event-topology variables, are used as inputs to an Artificial Neural Network for the final electron-neutrino identification. The design and implementation of this algorithm is also presented.