1,779 research outputs found
Understanding CP phase-dependent measurements at neutrino superbeams in terms of bi-rate graphs
We discuss the impact of the true value of the CP phase on the mass
hierarchy, CP violation, and CP precision measurements at neutrino superbeams
and related experiments. We we use a complete statistical experiment simulation
including spectral information, systematics, correlations, and degeneracies to
produce the results. However, since it is very complicated to understand the
results in terms of a complete experiment simulation, we show the corresponding
bi-rate graphs as useful tools to investigate the CP phase-dependencies
qualitatively. Unlike bi-probability graphs, which are based upon oscillation
probabilities, bi-rate graphs use the total event rates of two measurements
simultaneously as a function of the CP phase. Since they allow error bars for
direct quantitative estimates, they can be used for a direct comparison with a
complete statistical experiment simulation. We find that one can describe the
CP phase dependencies of the mentioned measurements at neutrino superbeam
setups, as well as one can understand the role of the -degeneracy. As one of the most interesting results, we discuss the
dependence of the CP precision measurement as a function of the CP phase
itself, which leads to ``CP patterns''. It turns out that this dependence is
rather strong, which means that one has to be careful when one is comparing the
CP precisions of different experiments.Comment: Major revisions: Scope reduced and discussions simplified. Summary
and conclusions unchanged. 14 pages, 4 figures. Final version to appear in
PR
Resolving degeneracies for different values of
We discuss options to resolve correlations and degeneracies with combinations
of future neutrino long-baseline experiments. We use a logarithmic scale of
as a representation for a systematical classification of
the experiments.Comment: 4 pages, Proceedings of NuFact 03, 5th International Workshop on
Neutrino Factories & Superbeams, 5-11 June 2003, Columbia University, New
Yor
How astrophysical neutrino sources could be used for early measurements of neutrino mass hierarchy and leptonic CP phase
We discuss the possible impact of astrophysical neutrino flux measurements at
neutrino telescopes on the neutrino oscillation program of reactor experiments
and neutrino beams. We consider neutrino fluxes from neutron sources, muon
damped sources, and pion sources, where we parameterize the input from these
sources in terms of the flux ratio which can be
extracted from the muon track to shower ratio in a neutrino telescope. While it
is difficult to obtain any information from this ratio alone, we demonstrate
that the dependence on the oscillation parameters is very complementary to the
one of reactor experiments and neutrino beams. We find that for large values of
, a measurement of R with a precision of about 20% or
better may not only improve the measurement of the leptonic CP phase, but also
help the determination of the mass hierarchy. In some cases, early information
on may even be obtained from Double Chooz and an astrophysical
flux alone without the help of superbeams. For small values of , we find that using the information from an astrophysical neutrino
flux could eliminate the octant degeneracy better than reactor experiments and
beams alone. Finally, we demonstrate that implementing an additional observable
based on the electromagnetic to hadronic shower ratio at a neutrino telescope
(such as at higher energies) could be especially beneficial for pion beam
sources.Comment: Minor changes and additions, final version to appear in PRD. 32
pages, 15 figure
Lectures on neutrino phenomenology
The fundamental properties of the lepton sector include the neutrino masses
and flavor mixings. Both are difficult to observe because of the extremely
small neutrino masses and neutrino-matter cross sections. In these lectures, we
focus on the basic concepts for the determination of neutrino properties. We
introduce neutrino oscillations as standard mechanism for neutrino flavor
changes, and we discuss methods to measure the neutrino mass. Furthermore, we
illustrate how precision measurements in neutrino oscillations will be
performed in the future, and may even open a window to new physics properties,
such as motivated by LHC physics. Finally, we discuss some applications of
neutrinos in astrophysics, such as neutrino oscillations in the Sun. We also
illustrate how neutrinos from extragalactic cosmic accelerators may be used for
the determination of neutrino properties.Comment: 37 pages, 13 figures, 1 table. Lectures given at the Schladming
Winter School 2010 "Masses and Constants"
Optimization of a Very Low Energy Neutrino Factory for the Disappearance Into Sterile Neutrinos
We discuss short-baseline electron and muon neutrino disappearance searches
into sterile neutrinos at a Very Low Energy Neutrino Factory (VLENF) with a
muon energy between about two and four GeV. A lesson learned from reactor
experiments, such as Double Chooz and Daya Bay, is to use near and far
detectors with identical technologies to reduce the systematical errors. We
therefore derive the physics results from a combined near-far detector fit and
illustrate that uncertainties on cross sections x efficiencies can be
eliminated in a self-consistent way. We also include the geometry of the setup,
i.e., the extension of the decay straight and the muon decay kinematics
relevant at the near detector, and we demonstrate that these affect the
sensitivities for Delta m^2 > 30 eV^2, where oscillations take place already in
the near detector. Compared to appearance searches, we find that the
sensitivity depends on the locations of both detectors and the muon energy,
where the near detector should be as close as possible to the source, and the
far detector at about 500 to 800m. In order to exclude the currently preferred
parameter region, at least 10^19 useful muon decays per polarity are needed for
E_mu=2 GeV, or, alternatively, a higher muon energy can be used.Comment: 16 pages, 6 figure
Neutrino mass hierarchy determination with IceCube-PINGU
We discuss the neutrino mass hierarchy determination with atmospheric
neutrinos in PINGU (Precision IceCube Next Generation Upgrade), based on a
simulation with the GLoBES software including the full three flavor framework
and parameter degeneracy, and we compare it to long-baseline experiment
options. We demonstrate that the atmospheric mass hierarchy sensitivity depends
on the achievable experiment properties and we identify the main targets for
optimization, whereas the impact of a large number of tested systematical
errors turns out to be small. Depending on the values of theta_23, delta, and
the true hierarchy, a 90% CL to 3sigma discovery after three years of operation
seems conceivable. We also emphasize the synergy with existing beam and reactor
experiments, driven by NOvA, such as the complementary coverage of the
parameter space. Finally, we point out that a low intensity neutrino beam with
a relatively short decay pipe could be used to determine the mass hierarchy
with a sensitivity comparable to the LBNE experiment irrespective of the
directional resolution of the detector.Comment: 22 pages, 9 figures, 1 table. Several clarifications, T2K data
removed from main line of analysis. Version accepted for publication in Phys.
Rev.
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