22 research outputs found
The OPERA experiment
OPERA is a neutrino oscillation experiment designed to perform a nu\_tau
appearance search at long distance in the future CNGS beam from CERN to Gran
Sasso. It is based on the nuclear emulsion technique to distinguish among the
neutrino interaction products the track of a tau produced by a nu\_tau and its
decay tracks. The OPERA detector is presently under construction in the Gran
Sasso underground laboratory, 730 km from CERN, and will receive its first
neutrinos in 2006. The experimental technique is reviewed and the development
of the project described. Foreseen performances in measuring nu\_tau appearance
and also in searching for nu\_e appearance are discussed
First hint for CP violation in neutrino oscillations from upcoming superbeam and reactor experiments
We compare the physics potential of the upcoming neutrino oscillation
experiments Daya Bay, Double Chooz, NOvA, RENO, and T2K based on their
anticipated nominal luminosities and schedules. After discussing the
sensitivity to theta_{13} and the leading atmospheric parameters, we
demonstrate that leptonic CP violation will hardly be measurable without
upgrades of the T2K and NOvA proton drivers, even if theta_{13} is large. In
the presence of the proton drivers, the fast track to hints for CP violation
requires communication between the T2K and NOvA collaborations in terms of a
mutual synchronization of their neutrino-antineutrino run plans. Even in that
case, upgrades will only discover CP violation in a relatively small part of
the parameter space at the 3 sigma confidence level, while 90% confidence level
hints will most likely be obtained. Therefore, we conclude that a new facility
will be required if the goal is to obtain a significant result with high
probability.Comment: 27 pages, 12 figure
Underground Neutrino Detectors for Particle and Astroparticle Science: the Giant Liquid Argon Charge Imaging ExpeRiment (GLACIER)
The current focus of the CERN program is the Large Hadron Collider (LHC),
however, CERN is engaged in long baseline neutrino physics with the CNGS
project and supports T2K as recognized CERN RE13, and for good reasons: a
number of observed phenomena in high-energy physics and cosmology lack their
resolution within the Standard Model of particle physics; these puzzles include
the origin of neutrino masses, CP-violation in the leptonic sector, and baryon
asymmetry of the Universe. They will only partially be addressed at LHC. A
positive measurement of would certainly give a
tremendous boost to neutrino physics by opening the possibility to study CP
violation in the lepton sector and the determination of the neutrino mass
hierarchy with upgraded conventional super-beams. These experiments (so called
``Phase II'') require, in addition to an upgraded beam power, next generation
very massive neutrino detectors with excellent energy resolution and high
detection efficiency in a wide neutrino energy range, to cover 1st and 2nd
oscillation maxima, and excellent particle identification and
background suppression. Two generations of large water Cherenkov
detectors at Kamioka (Kamiokande and Super-Kamiokande) have been extremely
successful. And there are good reasons to consider a third generation water
Cherenkov detector with an order of magnitude larger mass than Super-Kamiokande
for both non-accelerator (proton decay, supernovae, ...) and accelerator-based
physics. On the other hand, a very massive underground liquid Argon detector of
about 100 kton could represent a credible alternative for the precision
measurements of ``Phase II'' and aim at significantly new results in neutrino
astroparticle and non-accelerator-based particle physics (e.g. proton decay).Comment: 31 pages, 14 figure
Apparent Lorentz violation with superluminal Majorana neutrinos at OPERA?
From the data release of OPERA - CNGS experiment, and publicly announced on
23 September 2011, we cast a phenomenological model based on a Majorana
neutrino state carrying a fictitious imaginary mass term, already discussed by
Majorana in 1932. This mass term can be induced by the interaction with the
matter of the Earth's crust during the 735 Km travel. Within the experimental
errors, we prove that the model fits with OPERA, MINOS and supernova SN1987a
data. Possible violations to Lorentz invariance due to quantum gravity effects
have been considered.Comment: 4 pages, 1 figure, 1 table, updated with new data, new figure. Higgs
mass expected at (273.56 {\pm} 0.01) Ge
Proton driver optimization for new generation neutrino superbeams to search for sub-leading numu->nue oscillations ( angle)
We perform a systematic study of particle production and neutrino yields for
different incident proton energies and baselines , with the aim of
optimizing the parameters of a neutrino beam for the investigation of
-driven neutrino oscillations in the range allowed by
Superkamiokande results. We study the neutrino energy spectra in the
``relevant'' region of the first maximum of the oscillation at a given baseline
. We find that to each baseline corresponds an ``optimal'' proton energy
which minimizes the required integrated proton intensity needed to
observe a fixed number of oscillated events. In addition, we find that the
neutrino event rate in the relevant region scales approximately linearly with
the proton energy. Hence, baselines and proton energies can be
adjusted and the performance for neutrino oscillation searches will remain
approximately unchanged provided that the product of the proton energy times
the number of protons on target remains constant. We apply these ideas to the
specific cases of 2.2, 4.4, 20, 50 and 400 GeV protons. We simulate focusing
systems that are designed to best capture the secondary pions of the
``optimal'' energy. We compute the expected sensitivities to
for the various configurations by assuming the existence
of new generation accelerators able to deliver integrated proton intensities on
target times the proton energy of the order of ${\cal O}(5\times 10^{23})\rm\
GeV\times\rm pot/year$.Comment: 39 pages, 17 figure
Weakness of accelerator bounds on electron superluminality without a preferred frame
The reference laboratory bounds on superluminality of the electron are
obtained from the absence of in-vacuo Cherenkov processes and the
determinations of synchrotron radiated power for LEP electrons. It is usually
assumed that these analyses establish the validity of a standard
special-relativistic description of the electron with accuracy of at least a
few parts in , and in particular this is used to exclude electron
superluminality with such an accuracy. We observe that these bounds rely
crucially on the availability of a preferred frame. In-vacuo-Cherenkov
processes are automatically forbidden in any theory with "deformed Lorentz
symmetry", relativistic theories that, while different from Special Relativity,
preserve the relativity of inertial frames. Determinations of the synchrotron
radiated power can be used to constrain the possibility of Lorentz-symmetry
deformation, but provide rather weak bounds, which in particular for electron
superluminality we establish to afford us no more constraining power than for
an accuracy of a few parts in . We argue that this observation can have
only a limited role in the ongoing effort of analysis of the anomaly
tentatively reported by the OPERA collaboration, but we stress that it could
provide a valuable case study for assessing the limitations of "indirect" tests
of fundamental laws of physics.Comment: LaTex, 6 page
Emulsion sheet doublets as interface trackers for the OPERA experiment
New methods for efficient and unambiguous interconnection between electronic
counters and target units based on nuclear photographic emulsion films have
been developed. The application to the OPERA experiment, that aims at detecting
oscillations between mu neutrino and tau neutrino in the CNGS neutrino beam, is
reported in this paper. In order to reduce background due to latent tracks
collected before installation in the detector, on-site large-scale treatments
of the emulsions ("refreshing") have been applied. Changeable Sheet (CSd)
packages, each made of a doublet of emulsion films, have been designed,
assembled and coupled to the OPERA target units ("ECC bricks"). A device has
been built to print X-ray spots for accurate interconnection both within the
CSd and between the CSd and the related ECC brick. Sample emulsion films have
been extensively scanned with state-of-the-art automated optical microscopes.
Efficient track-matching and powerful background rejection have been achieved
in tests with electronically tagged penetrating muons. Further improvement of
in-doublet film alignment was obtained by matching the pattern of low-energy
electron tracks. The commissioning of the overall OPERA alignment procedure is
in progress.Comment: 19 pages, 19 figure
Study of the effects induced by lead on the emulsion films of the OPERA experiment
The OPERA neutrino oscillation experiment is based on the use of the Emulsion
Cloud Chamber (ECC). In the OPERA ECC, nuclear emulsion films acting as very
high precision tracking detectors are interleaved with lead plates providing a
massive target for neutrino interactions. We report on studies related to the
effects occurring from the contact between emulsion and lead. A low
radioactivity lead is required in order to minimize the number of background
tracks in emulsions and to achieve the required performance in the
reconstruction of neutrino events. It was observed that adding other chemical
elements to the lead, in order to improve the mechanical properties, may
significantly increase the level of radioactivity on the emulsions. A detailed
study was made in order to choose a lead alloy with good mechanical properties
and an appropriate packing technique so as to have a low enough effective
radioactivity.Comment: 19 pages, 11 figure