1,721,045 research outputs found
Latest results from Double Chooz
No full textDouble Chooz is a short-baseline neutrino disappearance experiment. It detects ν̄e produced in the power plant of Chooz, France, where is located. The main goal of the experiment is the measurement of θ13 mixing angle and in 2011 for the first time the experiment observed an indication for a non zero value of such an oscillation parameter. The mixing angle was successively measured using only the far detector finding the best fit value of sin2(2θ13) = 0.090−0.029+0.032. The near detector is under construction and will start data taking by the middle of 2014 allowing the reduction of the systematic errors. In this paper I make a review of the Double Chooz experiment, focusing in particular on the latest results of the measurement of the mixing angle θ13 relying on the neutron absorption on Gadolinium. I also present results proving the capability of Double Chooz to identify the ortho-positronium. This has been done in an event-by-event basis for the first time in a large liquid scintillator experiments, and can be an additional handle for the electron/positron discrimination in future detectors based on such technology
The EUROnu Study for Future High Power Neutrino Oscillation Facilities
No full textThe EUROnu project was a 4 year FP7 design study to investigate and compare three possible options for future, high power neutrino oscillation facilities in Europe. These three facilities are a Neutrino Factory, a neutrino superbeam from CERN to the Frejus Laboratory and a so-called Beta Beam. The study was completed at the end of 2012 and has produced conceptual designs for the facilities and preliminary cost estimates. The designs were used to determine the physics performance. These have been used to compare the facilities. This paper will describe the designs, physics performance and costs and summarise the recommendations of the study
Three flavor implications of the result of the CHOOZ Collaboration
No full textWe analyze the recent result of the CHOOZ Collaboration in the context of mixing and oscillations between all the three neutrino flavors. If one assumes the hierarchy among the vacuum mass eigenvalues δ21≪δ31 where δ21=μ22-μ12 and δ31=μ32-μ;12, then the CHOOZ result puts a strong constraint on the allowed values of the (13) mixing angle φ. It is also shown that, in light of the CHOOZ result, the maximum contribution of the νμ↔νe oscillation channel to the atmospheric neutrino anomaly is less than 7 percent, thus demonstrating that the atmospheric neutrino anomaly is mainly due to νμ↔ντ oscillations. Most importantly the CHOOZ result now excludes a large part of the three flavor parameter space which was previously allowed as solutions to the solar and atmospheric neutrino problems
Three flavor implications of the result of the CHOOZ Collaboration
No full textWe analyze the recent result of the CHOOZ Collaboration in the context of mixing and oscillations between all the three neutrino flavors. If one assumes the hierarchy among the vacuum mass eigenvalues delta(21) much less than delta(31) Where delta(21) = mu(22) - mu(1)(2) and delta(31) = mu(3)(2) - mu(1)(2), then the CHOOZ result puts a strong constraint on the allowed values of the (13) mixing angle phi. It is also shown that, in light of the CHOOZ result, the maximum contribution of the nu(mu) nu(e) oscillation channel to the atmospheric neutrino anomaly is less than 7 percent, thus demonstrating that the atmospheric neutrino anomaly is mainly due to nu(mu) nu(tau) oscillations. Most importantly the CHOOZ result now excludes a large part of the three flavor parameter space which was previously allowed as solutions to the solar and atmospheric neutrino problems. [S0556-2821(98)50415-8
Probing leptonic flavour with future long-baseline neutrino oscillation experiments
Full text linkOver the last 50 years, the study of the properties of neutrinos has unveiled a number of surprising facts that necessitate physics beyond the standard model. We now know that neutrinos are not only massive, but that there is a non-trivial alignment between the mass and flavour bases, inducing flavour changing transitions known as neutrino oscillations. Understanding the neutrino sector is a crucial first step in our attempts to extend our current theories of fundamental physics, and studies of neutrino oscillation provide us with a unique tool to probe these elusive particles. In this thesis, we assess the potential of the next generation of neutrino oscillation experiments to probe physical effects both within and beyond the current neutrino flavour paradigm: resolving existing unknowns, and constraining the correlations induced by theories of leptonic flavour
On the energy and baseline optimization to study effects related to the δ-phase (CP-/T-violation) in neutrino oscillations at a neutrino factory
No full textIn this paper we discuss the detection of CP- and T-violation effects in the framework of a neutrino factory. We introduce three quantities, which are good discriminants for a non-vanishing complex phase (δ) in the 3 × 3 neutrino mixing matrix: Δδ, ΔCP and ΔT. We find that these three discriminants (in vacuum) all scale with L/Ev, where L is the baseline and Ev the neutrino energy. Matter effects modify the scaling, but these effects are large enough to spoil the sensitivity only for baselines larger than 5000 km. So, in the hypothesis of constant neutrino factory power (i.e., number of muons inversely proportional to muon energy), the sensitivity on the δ-phase is independent of the baseline chosen. Specially interesting is the direct measurement of T-violation from the "wrong-sign" electron channel (i.e., the ΔT discriminant), which involves a comparison of the ve → vμ and vμ → ve oscillation rates. However, the vμ → ve measurement requires magnetic discrimination of the electron charge, experimentally very challenging in a neutrino detector. Since the direction of the electron curvature has to be estimated before the start of the electromagnetic shower, low-energy neutrino beams and hence short baselines, are preferred. In this paper we show, as an example, the exclusion regions in the Δm212-δ plane using the ΔCP and ΔT discriminants for two concrete cases keeping the same L/Ev ratio (730 km/7.5 GeV and 2900 km/30 GeV). We obtain a similar excluded region provided that the electron detection efficiency is ∼20% and the charge confusion 0.1%. The Δm212 compatible with the LMA solar data can be tested with a flux of 5 × 1021 muons. We compare these results with the fit of the visible energy distributions. © 2002 Elsevier Science B.V. All rights reserved
Measurement of θ_13 in Double Chooz using neutron captures on hydrogen with novel background rejection techniques
No full textThe Double Chooz collaboration presents a measurement of the neutrino mixing angle using reactor observed via the inverse beta decay reaction in which the neutron is captured on hydrogen. This measurement is based on 462.72 live days data, approximately twice as much data as in the previous such analysis, collected with a detector positioned at an average distance of 1050 m from two reactor cores. Several novel techniques have been developed to achieve significant reductions of the backgrounds and systematic uncertainties. Accidental coincidences, the dominant background in this analysis, are suppressed by more than an order of magnitude with respect to our previous publication by a multi-variate analysis. These improvements demonstrate the capability of precise measurement of reactor without gadolinium loading. Spectral distortions from the reactor flux predictions previously reported with the neutron capture on gadolinium events are confirmed in the independent data sample presented here. A value of sin² 2 = (stat+syst) is obtained from a fit to the observed event rate as a function of the reactor power, a method insensitive to the energy spectrum shape. A simultaneous fit of the hydrogen capture events and of the gadolinium capture events yields a measurement of sin² 2 = 0.088 ± 0.033(stat+syst)
- …
