659 research outputs found
Input-image homogenization as a method to improve a correlator's discrimination capability
We propose an input-image preprocessing method consisting of homogenization of the image to improve the discrimination capability of a correlation-based recognition process. This method is an approximation of the optimal filter. It offers the advantage that correlation with the preprocessed images can easily be implemented in an optical correlator working with phase-only spatial light modulators
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
GeV-scale neutrinos: interactions with mesons and DUNE sensitivity
The simplest extension of the SM to account for the observed neutrino masses
and mixings is the addition of at least two singlet fermions (or right-handed
neutrinos). If their masses lie at or below the GeV scale, such new fermions
would be produced in meson decays. Similarly, provided they are sufficiently
heavy, their decay channels may involve mesons in the final state. Although the
couplings between mesons and heavy neutrinos have been computed previously,
significant discrepancies can be found in the literature. The aim of this paper
is to clarify such discrepancies and provide consistent expressions for all
relevant effective operators involving mesons with masses up to 2 GeV.
Moreover, the effective Lagrangians obtained for both the Dirac and Majorana
scenarios are made publicly available as FeynRules models so that fully
differential event distributions can be easily simulated. As an application of
our setup, we numerically compute the expected sensitivity of the DUNE near
detector to these heavy neutral leptons.Comment: v4: Minor updates and text modifications. Published in EPJC.
FeynRules models performance improved, B mesons include
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
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
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
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
Role of the support and chloride during the purification of 1‐pentene in alkyne/alkene streams over Pd catalysts
BACKGROUND: Pd nanoparticles over different supports were evaluated during the alkyne selective hydrogenation of medium chain (C7 and C5) and the 1‐pentene purification at mild operational conditions (150 kPa and 303 K). The role of support and chloride was investigated; γ‐Al2O3, γ‐Al2O3 modified with Mg, CaCO3 and activated carbon were used as supports, and PdCl2 as precursor salt. The classical Lindlar catalyst was used as reference. RESULTS: Surface acidity of supports, active sites dispersion and surface species (MgO, PdxClyOz and/or functional groups) can favor or disfavor the desorption of 1‐alkene during the purification of 1‐pentene stream. The smallest particle sizes (3.8–10.0 nm) favor the dissociative adsorption of hydrogen over Pd° active sites, promoting good catalytic behavior. The best synthesized catalysts are Pd/Al–Mg and Pd/Ca, and their high selectivity (≥90%) is favored by the presence of superficial acidic Lewis sites. On the contrary, lower selectivity (74–80%) is assessed on catalysts with Brönsted acidic sites (Pd/Al and Pd/RX3) that favored the undesired overhydrogenation or isomerization reactions. CONCLUSION: The geometric and electronic properties of the support have a major influence on the activity and selectivity of the catalysts. Low loaded Pd catalysts supported on Al2O3‐Mg and CaCO3 (Pd/Al‐Mg, Pd/Ca) can be used for the purification of medium or large terminal alkenes at mild reaction conditions as an alternative to the toxic Lindlar commercial catalyst.The financial support provided by Universidad Nacional del Litoral (UNL, Grants CAI+D), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET, Grant PIP 11220130100457CO), and Agencia Nacional de Promoción de Ciencia y Tecnológica (ANPCyT, Grants PICT 2016 and 2020) are acknowledged. L. García thanks Ministerio de Ciencia Tecnología e Innovación de Colombia (Minciencias, Call 860, for Doctorates abroad 2019)
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