23 research outputs found
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
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
The detection of neutrino interactions in the emulsion/lead target of the OPERA experiment
The OPERA neutrino detector in the underground Gran Sasso Laboratory (LNGS)
was designed to perform the first detection of neutrino oscillations in
appearance mode through the study of oscillations. The
apparatus consists of an emulsion/lead target complemented by electronic
detectors and it is placed in the high energy long-baseline CERN to LNGS beam
(CNGS) 730 km away from the neutrino source. Runs with CNGS neutrinos were
successfully carried out in 2007 and 2008 with the detector fully operational
with its related facilities for the emulsion handling and analysis. After a
brief description of the beam and of the experimental setup we report on the
collection, reconstruction and analysis procedures of first samples of neutrino
interaction events
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
Determination of the muon charge sign with the dipolar spectrometers of the OPERA experiment
The OPERA long-baseline neutrino-oscillation experiment has observed the
direct appearance of in the CNGS beam. Two large muon
magnetic spectrometers are used to identify muons produced in the
leptonic decay and in interactions by measuring their charge and
momentum. Besides the kinematic analysis of the decays, background
resulting from the decay of charmed particles produced in
interactions is reduced by efficiently identifying the muon track. A new method
for the charge sign determination has been applied, via a weighted angular
matching of the straight track-segments reconstructed in the different parts of
the dipole magnets. Results obtained for Monte Carlo and real data are
presented. Comparison with a method where no matching is used shows a
significant reduction of up to 40\% of the fraction of wrongly determined
charges.Comment: 10 pages. Improvements in the tex
Limits on muon-neutrino to tau-neutrino oscillations induced by a sterile neutrino state obtained by OPERA at the CNGS beam
The OPERA experiment, exposed to the CERN to Gran Sasso beam,
collected data from 2008 to 2012. Four oscillated Charged Current
interaction candidates have been detected in appearance mode, which are
consistent with oscillations at the atmospheric within the "standard" three-neutrino framework. In this paper, the OPERA
appearance results are used to derive limits on the mixing
parameters of a massive sterile neutrino.Comment: 11 pages, 4 figures; reference to Planck result updated in the
Introduction. Submitted to JHE
Observation of nu_tau appearance in the CNGS beam with the OPERA experiment
The OPERA experiment is searching for nu_mu -> nu_tau oscillations in
appearance mode i.e. via the direct detection of tau leptons in nu_tau charged
current interactions. The evidence of nu_mu -> nu_tau appearance has been
previously reported with three nu_tau candidate events using a sub-sample of
data from the 2008-2012 runs. We report here a fourth nu_tau candidate event,
with the tau decaying into a hadron, found after adding the 2012 run events
without any muon in the final state to the data sample. Given the number of
analysed events and the low background, nu_mu -> nu_tau oscillations are
established with a significance of 4.2sigma.Comment: Submitted to Progress of Theoretical and Experimental Physics (PTEP
Measurement of the atmospheric muon charge ratio with the OPERA detector
The OPERA detector at the Gran Sasso underground laboratory (LNGS) was used
to measure the atmospheric muon charge ratio in the TeV energy region. We
analyzed 403069 atmospheric muons corresponding to 113.4 days of livetime
during the 2008 CNGS run. We computed separately the muon charge ratio for
single and for multiple muon events in order to select different energy regions
of the primary cosmic ray spectrum and to test the charge ratio dependence on
the primary composition. The measured charge ratio values were corrected taking
into account the charge-misidentification errors. Data have also been grouped
in five bins of the "vertical surface energy". A fit to a simplified model of
muon production in the atmosphere allowed the determination of the pion and
kaon charge ratios weighted by the cosmic ray energy spectrum.Comment: 14 pages, 10 figure
First events from the CNGS neutrino beam detected in the OPERA experiment
The OPERA neutrino detector at the underground Gran Sasso Laboratory (LNGS)
was designed to perform the first detection of neutrino oscillations in
appearance mode, through the study of nu_mu to nu_tau oscillations. The
apparatus consists of a lead/emulsion-film target complemented by electronic
detectors. It is placed in the high-energy, long-baseline CERN to LNGS beam
(CNGS) 730 km away from the neutrino source. In August 2006 a first run with
CNGS neutrinos was successfully conducted. A first sample of neutrino events
was collected, statistically consistent with the integrated beam intensity.
After a brief description of the beam and of the various sub-detectors, we
report on the achievement of this milestone, presenting the first data and some
analysis results.Comment: Submitted to the New Journal of Physic
Final results on neutrino oscillation parameters from the OPERA experiment in the CNGS beam
International audienceThe OPERA experiment has conclusively observed the appearance of tau neutrinos in the muon neutrino CNGS beam. Exploiting the OPERA detector capabilities, it was possible to isolate high purity samples of Îœe, ΜΌ and ÎœÏ charged current weak neutrino interactions, as well as neutral current weak interactions. In this paper, the full dataset is used for the first time to test the three-flavor neutrino oscillation model and to derive constraints on the existence of a light sterile neutrino within the framework of the 3+1 neutrino model. For the first time, tau and electron neutrino appearance channels are jointly used to test the sterile neutrino hypothesis. A significant fraction of the sterile neutrino parameter space allowed by LSND and MiniBooNE experiments is excluded at 90% C.L. In particular, the best-fit values obtained by MiniBooNE combining neutrino and antineutrino data are excluded at 3.3Ï significance