53 research outputs found
Angular reconstruction of high energy air showers using the radio signal spectrum
The Hellenic Open University extensive air shower array (also known as
Astroneu array) is a small scale hybrid detection system operating in an area
with high levels of electromagnetic noise from anthropogenic activity. In the
present study we report the latest results of the data analysis concerning the
estimation of the shower direction using the spectrum of the RF system. In a
recent layout of the array, 4 RF antennas were operating receiving a common
trigger from an autonomous detection station of 3 particle detectors. The
directions estimated with the RF system are in very good agreement with the
corresponding estimations using the particle detectors demonstrating that a
single antenna has the potential for reconstructing the shower axis angular
direction
Solar axion search with the CAST experiment
The CAST (CERN Axion Solar Telescope) experiment is searching for solar
axions by their conversion into photons inside the magnet pipe of an LHC
dipole. The analysis of the data recorded during the first phase of the
experiment with vacuum in the magnet pipes has resulted in the most restrictive
experimental limit on the coupling constant of axions to photons. In the second
phase, CAST is operating with a buffer gas inside the magnet pipes in order to
extent the sensitivity of the experiment to higher axion masses. We will
present the first results on the data taking as well as the
system upgrades that have been operated in the last year in order to adapt the
experiment for the data taking. Expected sensitivities on the
coupling constant of axions to photons will be given for the recent run just started in March 2008.Comment: Proceedings of the ICHEP 2008 conferenc
Probing eV-scale axions with CAST
We have searched for solar axions or other pseudoscalar particles that couple
to two photons by using the CERN Axion Solar Telescope (CAST) setup. Whereas we
previously have reported results from CAST with evacuated magnet bores (Phase
I), setting limits on lower mass axions, here we report results from CAST where
the magnet bores were filled with \hefour gas (Phase II) of variable pressure.
The introduction of gas generated a refractive photon mass , thereby
achieving the maximum possible conversion rate for those axion masses \ma that
match . With 160 different pressure settings we have scanned \ma up
to about 0.4 eV, taking approximately 2 h of data for each setting. From the
absence of excess X-rays when the magnet was pointing to the Sun, we set a
typical upper limit on the axion-photon coupling of \gag\lesssim 2.17\times
10^{-10} {\rm GeV}^{-1} at 95% CL for \ma \lesssim 0.4 eV, the exact result
depending on the pressure setting. The excluded parameter range covers
realistic axion models with a Peccei-Quinn scale in the neighborhood of GeV. Currently in the second part of CAST Phase II, we are
searching for axions with masses up to about 1.2 eV using \hethree as a buffer
gas.Comment: 18 pages, 7 figures. Revised version of the paper after referee's
comments. Main changes on the gas sectio
Deep sea tests of a prototype of the KM3NeT digital optical module
The first prototype of a photo-detection unit of the future KM3NeT neutrino telescope has been deployed in the deepwaters of the Mediterranean Sea. This digital optical module has a novel design with a very large photocathode area segmented by the use of 31 three inch photomultiplier tubes. It has been integrated in the ANTARES detector for in-situ testing and validation. This paper reports on the first months of data taking and rate measurements. The analysis results highlight the capabilities of the new module design in terms of background suppression and signal recognition. The directionality of the optical module enables the recognition of multiple Cherenkov photons from the same (40)Kdecay and the localisation of bioluminescent activity in the neighbourhood. The single unit can cleanly identify atmospheric muons and provide sensitivity to the muon arrival directions
Detection potential of the KM3NeT detector for high-energy neutrinos from the Fermi bubbles
A recent analysis of the Fermi Large Area Telescope data provided evidence for a high-intensity emission of high-energy gamma rays with a E 2 spectrum from two large areas, spanning 50 above and below the
Galactic centre (the ‘‘Fermi bubbles’’). A hadronic mechanism was proposed for this gamma-ray emission making the Fermi bubbles promising source candidates of high-energy neutrino emission. In this work Monte Carlo simulations regarding the detectability of high-energy neutrinos from the Fermi bubbles
with the future multi-km3 neutrino telescope KM3NeT in the Mediterranean Sea are presented. Under the hypothesis that the gamma-ray emission is completely due to hadronic processes, the results indicate
that neutrinos from the bubbles could be discovered in about one year of operation, for a neutrino spectrum with a cutoff at 100 TeV and a detector with about 6 km3 of instrumented volume. The effect of a
possible lower cutoff is also considered.Published7–141.8. Osservazioni di geofisica ambientaleJCR Journalrestricte
Expansion cone for the 3-inch PMTs of the KM3NeT optical modules
[EN] Detection of high-energy neutrinos from distant astrophysical sources will open a new window on the Universe. The detection principle exploits the measurement of Cherenkov light emitted by charged particles resulting from neutrino interactions in the matter containing the telescope. A novel multi-PMT digital optical module (DOM) was developed to contain 31 3-inch photomultiplier tubes (PMTs). In order to maximize the detector sensitivity, each PMT will be surrounded by an expansion cone which collects photons that would otherwise miss the photocathode. Results for various angles of incidence with respect to the PMT surface indicate an increase in collection efficiency by 30% on average for angles up to 45 degrees with respect to the perpendicular. Ray-tracing calculations could reproduce the measurements, allowing to estimate an increase in the overall photocathode sensitivity, integrated over all angles of incidence, by 27% (for a single PMT). Prototype DOMs, being built by the KM3NeT consortium, will be equipped with these expansion cones.This work is supported through the EU, FP6 Contract no. 011937, FP7 grant agreement no. 212252, and the Dutch Ministry of Education, Culture and Science.Adrián Martínez, S.; Ageron, M.; Aguilar, JA.; Aharonian, F.; Aiello, S.; Albert, A.; Alexandri, M.... (2013). Expansion cone for the 3-inch PMTs of the KM3NeT optical modules. Journal of Instrumentation. 8(3):1-19. https://doi.org/10.1088/1748-0221/8/03/T03006S1198
Letter of intent for KM3NeT 2.0
The main objectives of the KM3NeT Collaboration are
(
i
)
the discovery and
subsequent observation of high-energy neutrino sources in the Universe and
(
ii
)
the determination of the mass hierarchy of neutrinos. These objectives are
strongly motivated by two recent important discoveries, namely:
(
1
)
the high-
energy astrophysical neutrino signal reported by IceCube and
(
2
)
the sizable
contribution of electron neutrinos to the third neutrino mass eigenstate as
reported by Daya Bay, Reno and others. To meet these objectives, the
KM3NeT Collaboration plans to build a new Research Infrastructure con-
sisting of a network of deep-sea neutrino telescopes in the Mediterranean Sea.
A phased and distributed implementation is pursued which maximises the
access to regional funds, the availability of human resources and the syner-
gistic opportunities for the Earth and sea sciences community. Three suitable
deep-sea sites are selected, namely off-shore Toulon
(
France
)
, Capo Passero
(
Sicily, Italy
)
and Pylos
(
Peloponnese, Greece
)
. The infrastructure will consist
of three so-called building blocks. A building block comprises 115 strings,
each string comprises 18 optical modules and each optical module comprises
31 photo-multiplier tubes. Each building block thus constitutes a three-
dimensional array of photo sensors that can be used to detect the Cherenkov
light produced by relativistic particles emerging from neutrino interactions.
Two building blocks will be sparsely con
fi
gured to fully explore the IceCube
signal with similar instrumented volume, different methodology, improved
resolution and complementary
fi
eld of view, including the galactic plane. One
building block will be densely con
fi
gured to precisely measure atmospheric
neutrino oscillations.
Original content from this work may be used under the ter
The ATLAS fast tracKer system
The ATLAS Fast TracKer (FTK) was designed to provide full tracking for the ATLAS high-level trigger by using pattern recognition based on Associative Memory (AM) chips and fitting in high-speed field programmable gate arrays. The tracks found by the FTK are based on inputs from all modules of the pixel and silicon microstrip trackers. The as-built FTK system and components are described, as is the online software used to control them while running in the ATLAS data acquisition system. Also described is the simulation of the FTK hardware and the optimization of the AM pattern banks. An optimization for long-lived particles with large impact parameter values is included. A test of the FTK system with the data playback facility that allowed the FTK to be commissioned during the shutdown between Run 2 and Run 3 of the LHC is reported. The resulting tracks from part of the FTK system covering a limited η-ϕ region of the detector are compared with the output from the FTK simulation. It is shown that FTK performance is in good agreement with the simulation. © The ATLAS collaboratio
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