2,324 research outputs found
EURONU WP6 2009 yearly report: Update of the physics potential of Nufact, superbeams and betabeams
Many studies in the last ten years have shown that we can measure the unknown
angle theta13, discover leptonic CP violation and determine the neutrino
hierarchy in more precise neutrino oscillation experiments, searching for the
subleading channel nue -> numu in the atmospheric range. In this first report
of WP6 activities the following new results are reviewed: (1) Re-evaluation of
the physics reach of the upcoming generation of experiments to measure theta13
and delta; (2) New tools to explore a larger parameter space as needed beyond
the standard scenario; (3) Neutrino Factory: (a) evaluation of the physics
reach of a Nufact regards sterile neutrinos; (b) evaluation of the physics
reach of a Nufact as regards non-standard interactions; (c) evaluation of the
physics reach of a Nufact as regards violation of unitarity; (d) critical
assessment on long baseline tau-detection at Nufact; (e) new physics searches
at a near detector in a Nufact; (4) Beta-beams: (a) choice of ions and location
for a gamma = 100 CERN-based beta-beam; (b) re-evaluation of atmospheric
neutrino background for the gamma = 100 beta-beam scenario; (c) study of a two
baseline beta-beam; (d) measuring absolute neutrino mass with beta-beams; (e)
progress on monochromatic beta-beams; (5) Update of the physics potential of
the SPL super-beam. Eventually, we present an updated comparison of the
sensitivity to theta13, delta and the neutrino mass hierarchy of several of the
different proposed facilities.Comment: 2009 Yearly report of the Working Package 6 (Physics) of the EUROnu
FP7 EU project. 55 pages, 21 figures
Precision on leptonic mixing parameters at future neutrino oscillation experiments
We perform a comparison of the different future neutrino oscillation
experiments based on the achievable precision in the determination of the
fundamental parameters theta_{13} and the CP phase, delta, assuming that
theta_{13} is in the range indicated by the recent Daya Bay measurement. We
study the non-trivial dependence of the error on delta on its true value. When
matter effects are small, the largest error is found at the points where CP
violation is maximal, and the smallest at the CP conserving points. The
situation is different when matter effects are sizable. As a result of this
effect, the comparison of the physics reach of different experiments on the
basis of the CP discovery potential, as usually done, can be misleading. We
have compared various proposed super-beam, beta-beam and neutrino factory
setups on the basis of the relative precision of theta_{13} and the error on
delta. Neutrino factories, both high-energy or low-energy, outperform
alternative beam technologies. An ultimate precision on theta_{13} below 3% and
an error on delta of < 7^{\circ} at 1 sigma (1 d.o.f.) can be obtained at a
neutrino factory.Comment: Minor changes, matches version accepted in JHEP. 30 pages, 9 figure
A minimal Beta Beam with high-Q ions to address CP violation in the leptonic sector
In this paper we consider a Beta Beam setup that tries to leverage at most
existing European facilities: i.e. a setup that takes advantage of facilities
at CERN to boost high-Q ions (8Li and 8B) aiming at a far detector located at L
= 732 Km in the Gran Sasso Underground Laboratory. The average neutrino energy
for 8Li and 8B ions boosted at \gamma ~ 100 is in the range E_\nu = [1,2] GeV,
high enough to use a large iron detector of the MINOS type at the far site. We
perform, then, a study of the neutrino and antineutrino fluxes needed to
measure a CP-violating phase delta in a significant part of the parameter
space. In particular, for theta_13 > 3 deg, if an antineutrino flux of 3 10^19
useful 8Li decays per year is achievable, we find that delta can be measured in
60% of the parameter space with 6 10^18 useful 8B decays per year.Comment: 19 pages, 10 figures, added references and corrected typo
A Beta Beam complex based on the machine upgrades for the LHC
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 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 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
that would provide evidence of appearance at T2K or
NOA (). Exploitation of matter effects at the
CERN to Gran Sasso distance provides sensitivity to the neutrino mass hierarchy
in significant areas of the plane
Optimized Two-Baseline Beta-Beam Experiment
We propose a realistic Beta-Beam experiment with four source ions and two
baselines for the best possible sensitivity to theta_{13}, CP violation and
mass hierarchy. Neutrinos from 18Ne and 6He with Lorentz boost gamma=350 are
detected in a 500 kton water Cerenkov detector at a distance L=650 km (first
oscillation peak) from the source. Neutrinos from 8B and 8Li are detected in a
50 kton magnetized iron detector at a distance L=7000 km (magic baseline) from
the source. Since the decay ring requires a tilt angle of 34.5 degrees to send
the beam to the magic baseline, the far end of the ring has a maximum depth of
d=2132 m for magnetic field strength of 8.3 T, if one demands that the fraction
of ions that decay along the straight sections of the racetrack geometry decay
ring (called livetime) is 0.3. We alleviate this problem by proposing to trade
reduction of the livetime of the decay ring with the increase in the boost
factor of the ions, such that the number of events at the detector remains
almost the same. This allows to substantially reduce the maximum depth of the
decay ring at the far end, without significantly compromising the sensitivity
of the experiment to the oscillation parameters. We take 8B and 8Li with
gamma=390 and 656 respectively, as these are the largest possible boost factors
possible with the envisaged upgrades of the SPS at CERN. This allows us to
reduce d of the decay ring by a factor of 1.7 for 8.3 T magnetic field.
Increase of magnetic field to 15 T would further reduce d to 738 m only. We
study the sensitivity reach of this two baseline two storage ring Beta-Beam
experiment, and compare it with the corresponding reach of the other proposed
facilities.Comment: 17 pages, 3 eps figures. Minor changes, matches version accepted in
JHE
Neutrino hierarchy from CP-blind observables with high density magnetized detectors
High density magnetized detectors are well suited to exploit the outstanding
purity and intensities of novel neutrino sources like Neutrino Factories and
Beta Beams. They can also provide independent measurements of leptonic mixing
parameters through the observation of atmospheric muon-neutrinos. In this
paper, we discuss the combination of these observables from a multi-kton iron
detector and a high energy Beta Beam; in particular, we demonstrate that even
with moderate detector granularities the neutrino mass hierarchy can be
determined for values greater than 4.Comment: 16 pages, 7 figures. Added a new section discussing systematic errors
(sec 5.2); sec.5.1 and 4 have been extended. Version to appear in EPJ
EUROnu-WP6 2010 Report
This is a summary of the work done by the Working Package 6 (Physics) of the
EU project "EUROnu" during the second year of activity of the project.Comment: 82 pages, 51 eps figure
Topical Review on "Beta-beams"
Neutrino physics is traversing an exciting period, after the important
discovery that neutrinos are massive particles, that has implications from
high-energy physics to cosmology. A new method for the production of intense
and pure neutrino beams has been proposed recently: the ``beta-beam''. It
exploits boosted radioactive ions decaying through beta-decay. This novel
concept has been the starting point for a new possible future facility. Its
main goal is to address the crucial issue of the existence of CP violation in
the lepton sector. Here we review the status and the recent developments with
beta-beams. We discuss the original, the medium and high-energy scenarios as
well as mono-chromatic neutrino beams produced through ion electron-capture.
The issue of the degeneracies is mentioned. An overview of low energy
beta-beams is also presented. These beams can be used to perform experiments of
interest for nuclear structure, for the study of fundamental interactions and
for nuclear astrophysics.Comment: Topical Review for Journal of Physics G: Nuclear and Particle
Physics, published version, minor corrections, references adde
The minimal 3+2 neutrino model versus oscillation anomalies
We study the constraints imposed by neutrino oscillation experiments on the minimal extension of the Standard Model that can explain neutrino masses, which requires the addition of just two singlet Weyl fermions. The most general renormalizable couplings of this model imply generically four massive neutrino mass eigenstates while one remains massless: it is therefore a minimal 3+2 model. The possibility to account for the confirmed solar, atmospheric and long-baseline oscillations, together with the LSND/MiniBooNE and reactor anomalies is addressed. We find that the minimal model can fit oscillation data including the anomalies better than the standard 3ν model and similarly to the 3+2 phenomenological models, even though the number of free parameters is much smaller than in the latter. Accounting for the anomalies in the minimal model favours a normal hierarchy of the light states and requires a large reactor angle, in agreement with recent measurements. Our analysis of the model employs a new parametrization of seesaw models that extends the Casas-Ibarra one to regimes where higher order corrections in the light-heavy mixings are significant
MiniBooNE and LSND data: non-standard neutrino interactions in a (3+1) scheme versus (3+2) oscillations
The recently observed event excess in MiniBooNE anti-neutrino data is in
agreement with the LSND evidence for electron anti-neutrino appearance. We
propose an explanation of these data in terms of a (3+1) scheme with a sterile
neutrino including non-standard neutrino interactions (NSI) at neutrino
production and detection. The interference between oscillations and NSI
provides a source for CP violation which we use to reconcile different results
from neutrino and anti-neutrino data. Our best fit results imply NSI at the
level of a few percent relative to the standard weak interaction, in agreement
with current bounds. We compare the quality of the NSI fit to the one obtained
within the (3+1) and (3+2) pure oscillation frameworks. We also briefly comment
on using NSI (in an effective two-flavour framework) to address a possible
difference in neutrino and anti-neutrino results from the MINOS experiment.Comment: 28 pages, 9 figures, discussion improved, new appendix added,
conclusions unchange
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