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We present the GLoBES ("General Long Baseline Experiment Simulator") software package, which allows the simulation of long-baseline and reactor neutrino oscillation experiments. One part of the software is the abstract experiment definition language to define experiments with beam and full detector descriptions as accurate as possible. Many systematics options are provided, such as normalization and energy calibration errors, or the choice between spectral or total rate information. For the definition of experiments, a new transparent building block concept is introduced. In addition, an additional program provides the possibility to develop and test new experiment definitions quickly. Another part of GLoBES is the user's interface, which provides probability, rate, and ∆χ 2 information for a given experiment or any combination of up to 32 experiments in C. Especially, the ∆χ 2 functions allow a simulation with statistics only, systematics, correlations, and degeneracies. In particular, GLoBES can handle the full multi-parameter correlation among the oscillation parameters, external input, and matter density uncertainties.

In this paper we study the effect of, well-known, higher order corrections to the allowed beta decay spectrum on the determination of anti-neutrino spectra resulting from the decays of fission fragments. In particular, we try to estimate the associated theory errors and find that induced currents like weak magnetism may ultimately limit our ability to improve the current accuracy and under certain circumstance could even largely increase the theoretical errors. We also perform a critical evaluation of the errors associated with our method to extract the anti-neutrino spectrum using synthetic beta spectra. It turns out, that a fit using only virtual beta branches with a judicious choice of the effective nuclear charge provides results with a minimal bias. We apply this method to actual data for 235 U, 239 Pu and 241 Pu and confirm, within errors, recent results, which indicate a net 3% upward shift in energy averaged anti-neutrino fluxes. However, we also find significant shape differences which can, in principle, be tested by high statistics anti-neutrino data samples.a

We present Version 3.0 of the GLoBES ("General Long Baseline Experiment Simulator") software, which is a simulation tool for short-and long-baseline neutrino oscillation experiments. As a new feature, GLoBES 3.0 allows for user-defined systematical errors, which can also be used to simulate experiments with multiple discrete sources and detectors. In addition, the combination with external information, such as from different experiment classes, is simplified. As far as the probability calculation is concerned, GLoBES now provides an interface for the inclusion of non-standard physics without re-compilation of the software. The set of experiment prototypes coming with GLoBES has been updated. For example, built-in fluxes are now provided for the simulation of beta beams.

We compare the physics potential of planned superbeams with the one of neutrino factories. Therefore, the experimental setups as well as the most relevant uncertainties and errors are considered on the same footing as much as possible. We use an improved analysis including the full parameter correlations, as well as statistical, systematical, and degeneracy errors. Especially, degeneracies have so far not been taken into account in a numerical analysis. We furthermore include external input, such as improved knowledge of the solar oscillation parameters from the KamLAND experiment. This allows us to determine the limiting uncertainties in all cases. For a specific comparison, we choose two representatives of each class: For the superbeam, we take the first conceivable setup, namely the JHF to SuperKamiokande experiment, as well as, on a longer time scale, the JHF to Hyper-Kamiokande experiment. For the neutrino factory, we choose an initially conceivable setup and an advanced machine. We determine the potential to measure the small mixing angle sin 2 2θ 13 , the sign of ∆m 2 31 , and the leptonic CP phase δ CP , which also implies that we compare the limitations of the different setups. We find interesting results, such as the complete loss of the sensitivity to the sign of ∆m 2 31 due to degeneracies in many cases. * Work supported by "Sonderforschungsbereich 375 für Astro-Teilchenphysik" der Deutschen Forschungsgemeinschaft and the "Studienstiftung des deutschen Volkes" (German National Merit Foundation) [W.W.]. a

A measurement of electron antineutrino oscillation by the Daya Bay Reactor Neutrino Experiment is described in detail. Six 2.9-GWth nuclear power reactors of the Daya Bay and Ling Ao nuclear power facilities served as intense sources of ν e 's. Comparison of theν e rate and energy spectrum measured by antineutrino detectors far from the nuclear reactors (∼1500-1950 m) relative to detectors near the reactors (∼350-600 m) allowed a precise measurement ofν e disappearance. More than 2.5 millionν e inverse beta-decay interactions were observed, based on the combination of 217 days of operation of six antineutrino detectors (December, 2011-July, 2012) with a subsequent 1013 days using the complete configuration of eight detectors (October, 2012-July, 2015. Theν e rate observed at the far detectors relative to the near detectors showed a significant deficit, R ¼ 0.949 AE 0.002ðstatÞAE 0.002ðsystÞ. The energy dependence ofν e disappearance showed the distinct variation predicted by neutrino oscillation. Analysis using an approximation for the three-flavor oscillation probability yielded the flavor-mixing angle sin 2 2θ 13 ¼ 0.0841 AE 0.0027ðstatÞ AE 0.0019ðsystÞ and the effective neutrino mass-squared difference of jΔm 2 ee j ¼ ð2.50 AE 0.06ðstatÞ AE 0.06ðsystÞÞ × 10 −3 eV 2 . Analysis using the exact three-flavor probability found Δm

We present a detailed quantitative discussion of the measurement of the leptonic mixing angle sin 2 2θ 13 with a future reactor neutrino oscillation experiment consisting of a near and far detector. We perform a thorough analysis of the impact of various systematical errors and compare the resulting physics potential to the one of planned first-generation superbeam experiments. Furthermore, we investigate the complementarity of both types of experiments. We find that, under realistic assumptions, a determination of sin 2 2θ 13 down to 10 −2 is possible with reactor experiments. They are thus highly competitive to firstgeneration superbeams and may be able to test sin 2 2θ 13 on shorter timescales. In addition, we find that the combination of a KamLAND-size reactor experiment with one or two superbeams could substantially improve the ability to access the neutrino mass hierarchy or the leptonic CP phase. * Work supported by "Sonderforschungsbereich 375 für Astro-Teilchenphysik" der Deutschen Forschungsgemeinschaft and the "Studienstiftung des deutschen Volkes" (German National Merit Foundation) [W.W.]. a