1,721,038 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
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
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)
Das Double Chooz Experiment
No full textDouble Chooz ist ein Reaktor-Antineutrino-Experiment, das gegenwärtig in der Nähe des Kernkraftwerks Chooz in Nordfrankreich aufgebaut wird. Ziel des Experiments ist die Bestimmung des letzten unbekannten Parameters der Neutrinomischungsmatrix theta_13, oder eine substantielle Verbesserung der momentan bekannten Obergrenze sin^2 (2 theta_13) < 0.14 (90% CL). Der Nachweis der Elektronantineutrinos erfolgt in einem neuentwickelten Gadolinium-beladenen Flüssigszintillator durch den inversen Betazerfall, wobei das Positronsignal und der folgende Gd-Neutroneneinfang die charakteristische Signatur einer zeitlich verzögerten Koinzidenz hervorrufen. Durch das Konzept zweier identischer Detektoren, die sich in unterschiedlichen Abständen zu den Reaktorkernen befinden, können systematische Unsicherheiten entscheidend reduziert werden, so dass nach 4 Jahren Datennahme eine Sensitivität von sin^2 (2 theta_13) = 0.03 (90% CL) erreicht werden kann. Mit der Fertigstellung des fernen Detektors werden im Frühjahr 2011 erste Daten erwartet, der nahe Detektor wird etwa eineinhalb Jahre später folgen
Precision Neutrino Mixing Angle Measurement with the Double Chooz Experiment and Latest Results
No full textBackground-independent measurement of theta(13) in Double Chooz
No full textThe oscillation results published by the Double Chooz Collaboration in 2011 and 2012 rely on background models substantiated by reactor-on data. In this analysis, we present a background-model-independent measurement of the mixing angle by including 7.53 days of reactor-off data. A global fit of the observed antineutrino rates for different reactor power conditions is performed, yielding a measurement of both and the total background rate. The results on the mixing angle are improved significantly by including the reactor-off data in the fit, as it provides a direct measurement of the total background rate. This reactor rate modulation analysis considers antineutrino candidates with neutron captures on both Gd and H, whose combination yields sin² (2)=0.102±0.028(stat.)±0.033(syst.). The results presented in this study are fully consistent with the ones already published by Double Chooz, achieving a competitive precision. They provide, for the first time, a determination of that does not depend on a background model
Yields and production rates of cosmogenic ⁹Li and ⁸He measured with the Double Chooz near and far detectors
No full textThe yields and production rates of the radioisotopes 9Li and 8He created by cosmic muon spallation on C, have been measured by the two detectors of the Double Chooz experiment. The identical detectors are located at separate sites and depths, which means that they are subject to different muon spectra. The near (far) detector has an overburden of ∼120 m.w.e. (∼300 m.w.e.) corresponding to a mean muon energy of 32.1 ± 2.0 GeV (63.7 ± 5.5 GeV). Comparing the data to a detailed simulation of the Li and He decays, the contribution of theHe radioisotope at both detectors is found to be compatible with zero. The observed Li yields in the near and far detectors are 5.51 ± 0.51 and 7.90 ± 0.51, respectively, in units of 10−8 μ −1g−1cm2. The shallow overburdens of the near and far detectors give a unique insight when combined with measurements by KamLAND and Borexino to give the first multi-experiment, data driven relationship between the Li yield and the mean muon energy according to the power law , giving and Y 0 = (0.43 ± 0.11) × 10−8 μ −1g−1cm2. This relationship gives future liquid scintillator based experiments the ability to predict their cosmogenic 9Li background rates
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