117 research outputs found

    A new design for the CERN-Fr\'ejus neutrino Super Beam

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    We present an optimization of the hadron focusing system for a low-energy high-intensity conventional neutrino beam (Super-Beam) proposed on the basis of the HP-SPL at CERN with a beam power of 4 MW and an energy of 4.5 GeV. The far detector would be a 440 kton Water Cherenkov detector (MEMPHYS) located at a baseline of 130 km in the Fr\'ejus site. The neutrino fluxes simulation relies on a new GEANT4 based simulation coupled with an optimization algorithm based on the maximization of the sensitivity limit on the θ13\theta_{13} mixing angle. A new configuration adopting a multiple horn system with solid targets is proposed which improves the sensitivity to θ13\theta_{13} and the CP violating phase δCP\delta_{CP}.Comment: 11 pages, 18 figures, 2 table

    Determination of the neutrino mass hierarchy in the regime of small matter effect

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    We point out a synergy between T-conjugated oscillation channels in the determination of the neutrino mass hierarchy with oscillation experiments with relatively short baselines (L < 700 km), where the matter effect is small. If information from all four oscillation channels νμνe\nu_\mu\to\nu_e, νˉμνˉe\bar\nu_\mu\to\bar\nu_e, νeνμ\nu_e\to\nu_\mu and νˉeνˉμ\bar\nu_e\to\bar\nu_\mu is available, a matter effect of few percent suffices to break the sign-degeneracy and allows to determine the neutrino mass hierarchy. The effect is discussed by analytical considerations of the relevant oscillation probabilities, and illustrated with numerical simulations of realistic experimental setups. Possible configurations where this method could be applied are the combination of a super beam experiment with a beta beam or a neutrino factory, or a (low energy) neutrino factory using a detector with muon and electron charge identification.Comment: 13 pages, 3 figure

    Neutrino oscillations and the effect of the finite lifetime of the neutrino source

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    We consider a neutrino source at rest and discuss a condition for the existence of neutrino oscillations which derives from the finite lifetime τS\tau_S of the neutrino source particle. This condition is present if the neutrino source is a free particle such that its wave function is non-stationary. For a Gaussian wave function and with some simplifying assumptions, we study the modification of the usual oscillation probability stemming from τS\tau_S. In the present accelerator experiments the effect of τS\tau_S can be neglected. We discuss some experimental situations where the source lifetime becomes relevant in the oscillation formula.Comment: 13 pages latex file with 2 figure

    Electron neutrino tagging through tertiary lepton detection

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    We discuss an experimental technique aimed at tagging electron neutrinos in multi-GeV artificial sources on an event-by-event basis. It exploits in a novel manner calorimetric and tracking technologies developed in the framework of the LHC experiments and of rare kaon decay searches. The setup is suited for slow-extraction, moderate power beams and it is based on an instrumented decay tunnel equipped with tagging units that intercept secondary and tertiary leptons from the bulk of undecayed \pi^+ and protons. We show that the taggers are able to reduce the \nue contamination originating from K_e3 decays by about one order of magnitude. Only a limited suppression (~60%) is achieved for \nue produced by the decay-in-flight of muons; for low beam powers, similar performance as for K_e3 can be reached supplementing the tagging system with an instrumented beam dump.Comment: 19 pages, 7 figures; minor changes, version to appear in EPJ

    Neutrino Beams From Electron Capture at High Gamma

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    We investigate the potential of a flavor pure high gamma electron capture electron neutrino beam directed towards a large water cherenkov detector with 500 kt fiducial mass. The energy of the neutrinos is reconstructed by the position measurement within the detector and superb energy resolution capabilities could be achieved. We estimate the requirements for such a scenario to be competitive to a neutrino/anti-neutrino running at a neutrino factory with less accurate energy resolution. Although the requirements turn out to be extreme, in principle such a scenario could achieve as good abilities to resolve correlations and degeneracies in the search for sin^2(2 theta_13) and delta_CP as a standard neutrino factory experiment.Comment: 21 pages, 7 figures, revised version, to appear in JHEP, Fig.7 extended, minnor changes, results unchange

    μe\mu-e conversion in nuclei within the CMSSM seesaw: universality versus non-universality

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    In this paper we study μe\mu-e conversion in nuclei within the context of the Constrained Minimal Supersymmetric Standard Model, enlarged by three right handed neutrinos and their supersymmetric partners, and where the neutrino masses are generated via a seesaw mechanism. Two different scenarios with either universal or non-universal soft supersymmetry breaking Higgs masses at the gauge coupling unification scale are considered. In the first part we present a complete one-loop computation of the conversion rate for this process that includes the photon-, ZZ-boson, and Higgs-boson penguins, as well as box diagrams, and compare their size in the two considered scenarios. Then, in these two scenarios we analyse the relevance of the various parameters on the conversion rates, particularly emphasising the role played by the heavy neutrino masses, tanβ\tan \beta, and especially θ13\theta_{13}. In the case of hierachical heavy neutrinos, an extremely high sensitivity of the rates to θ13\theta_{13} is indeed found. The last part of this work is devoted to the study of the interesting loss of correlation between the μe\mu-e conversion and μeγ\mu \to e \gamma rates that occurs in the non-universal scenario. In the case of large tanβ\tan \beta and light H0H^0 Higgs boson an enhanced ratio of the μe\mu-e to μeγ\mu \to e \gamma rates, with respect to the universal case is found, and this could be tested with the future experimental sensitivities.Comment: 48 pages, 15 figures. Minor typos corrected and some references adde

    Towards a unique formula for neutrino oscillations in vacuum

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    We show that all correct results obtained by applying quantum field theory to neutrino oscillations can be understood in terms of a single oscillation formula. In particular, the model proposed by Grimus and Stockinger is shown to be a subcase of the model proposed by Giunti, Kim and Lee, while the new oscillation formulas proposed by Ioannisian and Pilaftsis and by Shtanov are disproved. We derive an oscillation formula without making any relativistic assumption and taking into account the dispersion, so that the result is valid for both neutrinos and mesons. This unification gives a stronger phenomenological basis to the neutrino oscillation formula. We also prove that the coherence length can be increased without bound by more accurate energy measurements. Finally, we insist on the wave packet interpretation of the quantum field treatments of oscillations.Comment: 30 pages, 1 figure; the proof that plane wave oscillations do no exist is extended to stationary models; the influence of dispersion is explained in more detail

    A Beta Beam complex based on the machine upgrades for the LHC

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    The Beta Beam CERN design is based on the present LHC injection complex and its physics reach is mainly limited by the maximum rigidity of the SPS. In fact, some of the scenarios for the machine upgrades of the LHC, particularly the construction of a fast cycling 1 TeV injector (``Super-SPS''), are very synergic with the construction of a higher γ\gamma Beta Beam. At the energies that can be reached by this machine, we demonstrate that dense calorimeters can already be used for the detection of ν\nu at the far location. Even at moderate masses (40 kton) as the ones imposed by the use of existing underground halls at Gran Sasso, the CP reach is very large for any value of θ13\theta_{13} that would provide evidence of νe\nu_e appearance at T2K or NOν\nuA (θ133\theta_{13}\geq 3^\circ). Exploitation of matter effects at the CERN to Gran Sasso distance provides sensitivity to the neutrino mass hierarchy in significant areas of the θ13δ\theta_{13}-\delta plane

    θ13\theta_{13}, δ\delta and the neutrino mass hierarchy at a γ=350\gamma=350 double baseline Li/B β\beta-Beam

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    We consider a β\beta-Beam facility where 8^8Li and 8^8B ions are accelerated at γ=350\gamma = 350, accumulated in a 10 Km storage ring and let decay, so as to produce intense νˉe\bar \nu_e and νe\nu_e beams. These beams illuminate two iron detectors located at L2000L \simeq 2000 Km and L7000L \simeq 7000 Km, respectively. The physics potential of this setup is analysed in full detail as a function of the flux. We find that, for the highest flux (10×101810 \times 10^{18} ion decays per year per baseline), the sensitivity to θ13\theta_{13} reaches sin22θ132×104\sin^2 2 \theta_{13} \geq 2 \times10^{-4}; the sign of the atmospheric mass difference can be identified, regardless of the true hierarchy, for sin22θ134×104\sin^2 2 \theta_{13} \geq 4\times10^{-4}; and, CP-violation can be discovered in 70% of the δ\delta-parameter space for sin22θ13103\sin^2 2 \theta_{13} \geq 10^{-3}, having some sensitivity to CP-violation down to sin22θ13104\sin^2 2 \theta_{13} \geq 10^{-4} for δ90|\delta| \sim 90^\circ.Comment: 35 pages, 20 figures. Minor changes, matches the published versio

    The MSW Effect in Quantum Field Theory

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    We show in detail the general relationship between the Schr\"{o}dinger equation approach to calculating the MSW effect and the quantum field theoretical S-matrix approach. We show the precise form a generic neutrino propagator must have to allow a physically meaningful ``oscillation probability'' to be decoupled from neutrino production fluxes and detection cross-sections, and explicitly list the conditions---not realized in cases of current experimental interest---in which the field theory approach would be useful.Comment: 20 page REVTeX file, submitted to Phys. Rev.
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