2,514 research outputs found
CP violation and mass hierarchy at medium baselines in the large theta(13) era
The large value of theta(13) recently measured by rector and accelerator
experiments opens unprecedented opportunities for precision oscillation
physics. In this paper, we reconsider the physics reach of medium baseline
superbeams. For theta(13) ~ 9 degree we show that facilities at medium
baselines -- i.e. L ~ O(1000 km) -- remain optimal for the study of CP
violation in the leptonic sector, although their ultimate precision strongly
depends on experimental systematics. This is demonstrated in particular for
facilities of practical interest in Europe: a CERN to Gran Sasso and CERN to
Phyasalmi nu_mu beam based on the present SPS and on new high power 50 GeV
proton driver. Due to the large value of theta(13), spectral information can be
employed at medium baselines to resolve the sign ambiguity and determine the
neutrino mass hierarchy. However, longer baselines, where matter effects
dominate the nu_mu->nu_e transition, can achieve much stronger sensitivity to
sign(Delta m^2) even at moderate exposures.Comment: 14 pages, 14 figures, version to appear in EPJ
Time variations in the deep underground muon flux measured by MACRO
More than 30 million of high-energy muons collected with the MACRO detector
at the underground Gran Sasso Laboratory have been used to search for flux
variations of different natures. Two kinds of studies were carried out: search
for periodic variations and for the occurrence of clusters of events. Different
analysis methods, including Lomb-Scargle spectral analysis and Scan Test
statistics have been applied to the data.Comment: 6 pages, 4 EPS figures. Talk given at the 29th ICRC, Pune, India,
3-10 August 200
Search for exotic contributions to atmospheric neutrino oscillations
The energy spectrum of neutrino-induced upward-going muons in MACRO was
analysed in terms of relativity principles violating effects, keeping standard
mass-induced atmospheric neutrino oscillations as the dominant effect. The data
disfavor these possibilities even at a sub-dominant level; stringent 90% C.L.
limits are placed on the Lorentz invariance violation parameter at = 0 and at = 1. The limits can be re-interpreted as
bounds on the Equivalence Principle violation parameters.Comment: Presented at the 29th I.C.R.C., Pune, India (2005
Time variations in the deep underground muon flux
More than 35 million high-energy muons collected with the MACRO detector at
the underground Gran Sasso Laboratory have been used to search for flux
variations of different nature. Two kinds of studies were carried out: a search
for the occurrence of clusters of events and a search for periodic variations.
Different analysis methods, including the Scan Statistics test and the
Lomb-Scargle spectral analysis have been applied to the data.Comment: 7 pages, 5 figures, accepted by EP
Search for a Lorentz invariance violation contribution in atmospheric neutrino oscillations using MACRO data
Neutrino-induced upward-going muons in MACRO have been analysed in terms of
relativity principles violating effects, keeping standard mass-induced
atmospheric neutrino oscillations as the dominant source of nu_mu -> nu_tau
transitions. The data disfavor these exotic possibilities even at a
sub-dominant level, and stringent 90% C.L. limits are placed on the Lorentz
invariance violation parameter |Delta v| < 6 * 10^(-24) at sin2theta_v = 0 and
|Delta v| < 2.5--5 * 10^(-26) at sin2theta_v = +/-1. These limits can also be
re-interpreted as upper bounds on the parameters describing violation of the
Equivalence Principle.Comment: 8 pages, 2 figures, submitted to Physics Letters
Search for spontaneous muon emission from lead nuclei
We describe a possible search for muonic radioactivity from lead nuclei using
the base elements ("bricks" composed by lead and nuclear emulsion sheets) of
the long-baseline OPERA neutrino experiment. We present the results of a Monte
Carlo simulation concerning the expected event topologies and estimates of the
background events. Using few bricks, we could reach a good sensitivity level.Comment: 12 pages, 4 figure
Prospect for Charge Current Neutrino Interactions Measurements at the CERN-PS
Tensions in several phenomenological models grew with experimental results on
neutrino/antineutrino oscillations at Short-Baseline (SBL) and with the recent,
carefully recomputed, antineutrino fluxes from nuclear reactors. At a
refurbished SBL CERN-PS facility an experiment aimed to address the open issues
has been proposed [1], based on the technology of imaging in ultra-pure
cryogenic Liquid Argon (LAr). Motivated by this scenario a detailed study of
the physics case was performed. We tackled specific physics models and we
optimized the neutrino beam through a full simulation. Experimental aspects not
fully covered by the LAr detection, i.e. the measurements of the lepton charge
on event-by-event basis and their energy over a wide range, were also
investigated. Indeed the muon leptons from Charged Current (CC) (anti-)neutrino
interactions play an important role in disentangling different phenomenological
scenarios provided their charge state is determined. Also, the study of muon
appearance/disappearance can benefit of the large statistics of CC muon events
from the primary neutrino beam. Results of our study are reported in detail in
this proposal. We aim to design, construct and install two Spectrometers at
"NEAR" and "FAR" sites of the SBL CERN-PS, compatible with the already proposed
LAr detectors. Profiting of the large mass of the two Spectrometers their
stand-alone performances have also been exploited.Comment: 70 pages, 38 figures. Proposal submitted to SPS-C, CER
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