32 research outputs found

### Optimization of a neutrino factory oscillation experiment

We discuss the optimization of a neutrino factory experiment for neutrino
oscillation physics in terms of muon energy, baselines, and oscillation
channels (gold, silver, platinum). In addition, we study the impact and
requirements for detector technology improvements, and we compare the results
to beta beams. We find that the optimized neutrino factory has two baselines,
one at about 3000 to 5000km, the other at about 7500km (``magic'' baseline).
The threshold and energy resolution of the golden channel detector have the
most promising optimization potential. This, in turn, could be used to lower
the muon energy from about 50GeV to about 20GeV. Furthermore, the inclusion of
electron neutrino appearance with charge identification (platinum channel)
could help for large values of \sin^2 2 \theta_{13}. Though tau neutrino
appearance with charge identification (silver channel) helps, in principle, to
resolve degeneracies for intermediate \sin^2 2 \theta_{13}, we find that
alternative strategies may be more feasible in this parameter range. As far as
matter density uncertainties are concerned, we demonstrate that their impact
can be reduced by the combination of different baselines and channels. Finally,
in comparison to beta beams and other alternative technologies, we clearly can
establish a superior performance for a neutrino factory in the case \sin^2 2
\theta_{13} < 0.01.Comment: 51 pages, 25 figures, 6 tables, references corrected, final version
to appear in Phys. Rev.

### Physics and optimization of beta-beams: From low to very high gamma

The physics potential of beta beams is investigated from low to very high
gamma values and it is compared to superbeams and neutrino factories. The gamma
factor and the baseline are treated as continuous variables in the optimization
of the beta beam, while a fixed mass water Cherenkov detector or a totally
active scintillator detector is assumed. We include in our discussion also the
gamma dependence of the number of ion decays per year. For low gamma, we find
that a beta beam could be a very interesting alternative to a superbeam
upgrade, especially if it is operated at the second oscillation maximum to
reduce correlations and degeneracies. For high gamma, we find that a beta beam
could have a potential similar to a neutrino factory. In all cases, the
sensitivity of the beta beams to CP violation is very impressive if similar
neutrino and anti-neutrino event rates can be achieved.Comment: 34 pages, 16 figures, Fig. 2 modified, discussion improved, refs.
added, version to appear in PR

### Prospects of accelerator and reactor neutrino oscillation experiments for the coming ten years

We analyze the physics potential of long baseline neutrino oscillation
experiments planned for the coming ten years, where the main focus is the
sensitivity limit to the small mixing angle $\theta_{13}$. The discussed
experiments include the conventional beam experiments MINOS, ICARUS, and OPERA,
which are under construction, the planned superbeam experiments J-PARC to
Super-Kamiokande and NuMI off-axis, as well as new reactor experiments with
near and far detectors, represented by the Double-Chooz project. We perform a
complete numerical simulation including systematics, correlations, and
degeneracies on an equal footing for all experiments using the GLoBES software.
After discussing the improvement of our knowledge on the atmospheric parameters
$\theta_{23}$ and $\Delta m^2_{31}$ by these experiments, we investigate the
potential to determine $\theta_{13}$ within the next ten years in detail.
Furthermore, we show that under optimistic assumptions and for $\theta_{13}$
close to the current bound, even the next generation of experiments might
provide some information on the Dirac CP phase and the type of the neutrino
mass hierarchy.Comment: 38 pages, 13 figures, Eqs. (1) and (5) corrected, small corrections
in Figs. 8, 9, and Tab. 4, discussion improved, ref. added, version to appear
in PRD, high resolution figures are available at
http://www.sns.ias.edu/~winter/figs0403068.htm

### Combined potential of future long-baseline and reactor experiments

We investigate the determination of neutrino oscillation parameters by
experiments within the next ten years. The potential of conventional beam
experiments (MINOS, ICARUS, OPERA), superbeam experiments (T2K, NOvA), and
reactor experiments (D-CHOOZ) to improve the precision on the ``atmospheric''
parameters $\Delta m^2_{31}$, $\theta_{23}$, as well as the sensitivity to
$\theta_{13}$ are discussed. Further, we comment on the possibility to
determine the leptonic CP-phase and the neutrino mass hierarchy if
$\theta_{13}$ turns out to be large.Comment: 4 pages, 4 figures, Talk given by T.S. at the NOW2004 workshop, Conca
Specchiulla (Otranto, Italy), 11--17 Sept. 200

### Neutrino Beams From Electron Capture at High Gamma

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

### From Double Chooz to Triple Chooz - Neutrino Physics at the Chooz Reactor Complex

We discuss the potential of the proposed Double Chooz reactor experiment to
measure the neutrino mixing angle $\sin^2 2\theta_{13}$. We especially consider
systematical uncertainties and their partial cancellation in a near and far
detector operation, and we discuss implications of a delayed near detector
startup. Furthermore, we introduce Triple Chooz, which is a possible upgrade
scenario assuming a second, larger far detector, which could start data taking
in an existing cavern five years after the first far detector. We review the
role of the Chooz reactor experiments in the global context of future neutrino
beam experiments. We find that both Double Chooz and Triple Chooz can play a
leading role in the search for a finite value of $\sin^2 2\theta_{13}$. Double
Chooz could achieve a sensitivity limit of $\sim 2 \cdot 10^{-2}$ at the
90%~confidence level after 5~years while the Triple Chooz setup could give a
sensitivity below $10^{-2}$.Comment: 18 pages, 6 figure

### Reactor Neutrino Experiments with a Large Liquid Scintillator Detector

We discuss several new ideas for reactor neutrino oscillation experiments
with a Large Liquid Scintillator Detector. We consider two different scenarios
for a measurement of the small mixing angle $\theta_{13}$ with a mobile
$\bar{\nu}_e$ source: a nuclear-powered ship, such as a submarine or an
icebreaker, and a land-based scenario with a mobile reactor. The former setup
can achieve a sensitivity to $\sin^2 2\theta_{13} \lesssim 0.003$ at the 90%
confidence level, while the latter performs only slightly better than Double
Chooz. Furthermore, we study the precision that can be achieved for the solar
parameters, $\sin^2 2\theta_{12}$ and $\Delta m_{21}^2$, with a mobile reactor
and with a conventional power station. With the mobile reactor, a precision
slightly better than from current global fit data is possible, while with a
power reactor, the accuracy can be reduced to less than 1%. Such a precision is
crucial for testing theoretical models, e.g. quark-lepton complementarity.Comment: 18 pages, 3 figures, 2 tables, revised version, to appear in JHEP,
Fig. 1 extended, Formula added, minor changes, results unchange

### On a model with two zeros in the neutrino mass matrix

We consider a Majorana neutrino mass matrix $\mathcal{M}_\nu$ with
$(\mathcal{M}_\nu)_{\mu\mu} = (\mathcal{M}_\nu)_{\tau\tau} = 0$, in the basis
where the charged-lepton mass matrix is diagonal. We show that this pattern for
the lepton mass matrices can be enforced by extending the Standard Model with
three scalar SU(2) triplets and by using a horizontal symmetry group
\mathbbm{Z}_4. The Ma--Sarkar (type-II seesaw) mechanism leads to very small
vacuum expectation values for the triplets, thus explaining the smallness of
the neutrino masses; at the same time, that mechanism renders the physical
scalars originating in the triplets very heavy. We show that the conditions
$(\mathcal{M}_\nu)_{\mu\mu} = (\mathcal{M}_\nu)_{\tau\tau} = 0$ allow both for
a normal neutrino mass spectrum and for an inverted one. In the first case, the
neutrino masses must be larger than $0.1 {eV}$ and the atmospheric mixing angle
$\theta_{23}$ must be practically equal to $45^\circ$. In the second case, the
product $\sin{\theta_{13}} | \tan{2 \theta_{23}} |$ must be of order one or
larger, thus correlating the large or maximal atmospheric neutrino mixing with
the smallness of the mixing angle $\theta_{13}$.Comment: 13 pages, no figures, plain LaTeX; one equation added, published
references updated, final version for J. Phys.