101 research outputs found
Search for Neutrino Oscillations in Appearance Mode with the OPERA Experiment
The present paper highlights the data analysis status of the OPERA
experiment. The experiment was designed to perform the neutrino interactions
analysis on event-by-event basis, and optimized to search for oscillation in appearance mode, also allowing to
perform a appearance search.
We review the data simulation and the analysis chains implemented to search
for interactions. The main kinematical parameters sensitive to the
neutrino flavor are discussed, the uncertainties of the event parameter
estimation are reviewed, and the main sources of background for the oscillation search are examined. The topologies of the
two first candidate events are presented.
Finally, we review the status of the appearance search and present
the constraints set by the OPERA experiment on the mixing angle
and on the LSND/MiniBooNE anomaly.Comment: Mini-review of the OPERA experiment analysis status (October 2013), 9
pages, 5 figures, to appear in Proc. HEPFT-201
Electromagnetic cascade masquerade: a way to mimic --axion-like particle mixing effects in blazar spectra
Context. Most of the studies on extragalactic {\gamma}-ray propagation
performed up to now only accounted for primary gamma-ray absorption and
adiabatic losses ("absorption-only model"). However, there is growing evidence
that this model is oversimplified and must be modified in some way. In
particular, it was found that the intensity extrapolated from the
optically-thin energy range of some blazar spectra is insufficient to explain
the optically-thick part of these spectra. This effect was interpreted as an
indication for {\gamma}-axion-like particle (ALP) oscillation. On the other
hand, there are many hints that a secondary component from electromagnetic
cascades initiated by primary {\gamma}-rays or nuclei may be observed in the
spectra of some blazars. Aims. We study the impact of electromagnetic cascades
from primary {\gamma}-rays or protons on the physical interpretation of blazar
spectra obtained with imaging Cherenkov telescopes. Methods. We use the
publicly-available code ELMAG to compute observable spectra of electromagnetic
cascades from primary {\gamma}-rays. For the case of primary proton, we develop
a simple, fast and reasonably accurate hybrid method to calculate the
observable spectrum. We perform the fitting of the observed spectral energy
distributions (SEDs) with various physical models: the absorption-only model,
the "electromagnetic cascade model" (for the case of primary {\gamma}-rays),
and several versions of the hadronic cascade model (for the case of primary
proton). We distinguish the following species of hadronic cascade models: 1)
"basic hadronic model", where it is assumed that the proton beam travels
undisturbed by extragalactic magnetic field and that all observable
{\gamma}-rays are produced by primary protons through photohadronic processes
with subsequent development of electromagnetic cascades /abridgedComment: Accepted by A&A. 25 pages, 31 figures. Corrected fig. 5, fig. 7; new
explanations for fig. 6--7; several typos fixed wrt v.
Results and prospects on registration of reflected Cherenkov light of EAS from cosmic particles above 10^{15} eV
We give an overview of the SPHERE experiment based on detection of reflected
Vavilov-Cherenkov radiation (Cherenkov light) from extensive air showers in the
energy region E>10^{15} eV. A brief history of the reflected Cherenkov light
technique is given; the observations carried out with the SPHERE-2 detector are
summarized; the methods of the experimental datasample analysis are described.
The first results on the primary cosmic ray all-nuclei energy spectrum and mass
composition are presented. Finally, the prospects of the SPHERE experiment and
the reflected Cherenkov light technique are given.Comment: 4 pages, 3 figures, Proc. PANIC-201
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