257 research outputs found
The Power Board of the KM3NeT Digital Optical Module: design, upgrade, and production
The KM3NeT Collaboration is building an underwater neutrino observatory at
the bottom of the Mediterranean Sea consisting of two neutrino telescopes, both
composed of a three-dimensional array of light detectors, known as digital
optical modules. Each digital optical module contains a set of 31 three inch
photomultiplier tubes distributed over the surface of a 0.44 m diameter
pressure-resistant glass sphere. The module includes also calibration
instruments and electronics for power, readout and data acquisition. The power
board was developed to supply power to all the elements of the digital optical
module. The design of the power board began in 2013, and several prototypes
were produced and tested. After an exhaustive validation process in various
laboratories within the KM3NeT Collaboration, a mass production batch began,
resulting in the construction of over 1200 power boards so far. These boards
were integrated in the digital optical modules that have already been produced
and deployed, 828 until October 2023. In 2017, an upgrade of the power board,
to increase reliability and efficiency, was initiated. After the validation of
a pre-production series, a production batch of 800 upgraded boards is currently
underway. This paper describes the design, architecture, upgrade, validation,
and production of the power board, including the reliability studies and tests
conducted to ensure the safe operation at the bottom of the Mediterranean Sea
throughout the observatory's lifespa
Embedded Software of the KM3NeT Central Logic Board
The KM3NeT Collaboration is building and operating two deep sea neutrino
telescopes at the bottom of the Mediterranean Sea. The telescopes consist of
latices of photomultiplier tubes housed in pressure-resistant glass spheres,
called digital optical modules and arranged in vertical detection units. The
two main scientific goals are the determination of the neutrino mass ordering
and the discovery and observation of high-energy neutrino sources in the
Universe. Neutrinos are detected via the Cherenkov light, which is induced by
charged particles originated in neutrino interactions. The photomultiplier
tubes convert the Cherenkov light into electrical signals that are acquired and
timestamped by the acquisition electronics. Each optical module houses the
acquisition electronics for collecting and timestamping the photomultiplier
signals with one nanosecond accuracy. Once finished, the two telescopes will
have installed more than six thousand optical acquisition nodes, completing one
of the more complex networks in the world in terms of operation and
synchronization. The embedded software running in the acquisition nodes has
been designed to provide a framework that will operate with different hardware
versions and functionalities. The hardware will not be accessible once in
operation, which complicates the embedded software architecture. The embedded
software provides a set of tools to facilitate remote manageability of the
deployed hardware, including safe reconfiguration of the firmware. This paper
presents the architecture and the techniques, methods and implementation of the
embedded software running in the acquisition nodes of the KM3NeT neutrino
telescopes
Prospects for combined analyses of hadronic emission from -ray sources in the Milky Way with CTA and KM3NeT
The Cherenkov Telescope Array and the KM3NeT neutrino telescopes are major
upcoming facilities in the fields of -ray and neutrino astronomy,
respectively. Possible simultaneous production of rays and neutrinos
in astrophysical accelerators of cosmic-ray nuclei motivates a combination of
their data. We assess the potential of a combined analysis of CTA and KM3NeT
data to determine the contribution of hadronic emission processes in known
Galactic -ray emitters, comparing this result to the cases of two
separate analyses. In doing so, we demonstrate the capability of Gammapy, an
open-source software package for the analysis of -ray data, to also
process data from neutrino telescopes. For a selection of prototypical
-ray sources within our Galaxy, we obtain models for primary proton and
electron spectra in the hadronic and leptonic emission scenario, respectively,
by fitting published -ray spectra. Using these models and instrument
response functions for both detectors, we employ the Gammapy package to
generate pseudo data sets, where we assume 200 hours of CTA observations and 10
years of KM3NeT detector operation. We then apply a three-dimensional binned
likelihood analysis to these data sets, separately for each instrument and
jointly for both. We find that the largest benefit of the combined analysis
lies in the possibility of a consistent modelling of the -ray and
neutrino emission. Assuming a purely leptonic scenario as input, we obtain, for
the most favourable source, an average expected 68% credible interval that
constrains the contribution of hadronic processes to the observed -ray
emission to below 15%.Comment: 18 pages, 15 figures. Submitted to journa
Probing invisible neutrino decay with KM3NeT-ORCA
In the era of precision measurements of the neutrino oscillation parameters,
upcoming neutrino experiments will also be sensitive to physics beyond the
Standard Model. KM3NeT/ORCA is a neutrino detector optimised for measuring
atmospheric neutrinos from a few GeV to around 100 GeV. In this paper, the
sensitivity of the KM3NeT/ORCA detector to neutrino decay has been explored. A
three-flavour neutrino oscillation scenario, where the third neutrino mass
state decays into an invisible state, e.g. a sterile neutrino, is
considered. We find that KM3NeT/ORCA would be sensitive to invisible neutrino
decays with ~ at confidence
level, assuming true normal ordering. Finally, the impact of neutrino decay on
the precision of KM3NeT/ORCA measurements for ,
and mass ordering have been studied. No significant effect of neutrino decay on
the sensitivity to these measurements has been found.Comment: 27 pages, 14 figures, bibliography updated, typos correcte
KM3NeT broadcast optical data transport system
The optical data transport system of the KM3NeT neutrino telescope at the bottom of the Mediterranean Sea will provide more than 6000 optical modules in the detector arrays with a point-to-point optical connection to the control stations onshore. The ARCA and ORCA detectors of KM3NeT are being installed at a depth of about 3500 m and 2500 m, respectively and their distance to the control stations is about 100 kilometers and 40 kilometers. In particular, the two detectors are optimised for the detection of cosmic neutrinos with energies above about 1 TeV (ARCA) and for the detection of atmospheric neutrinos with energies in the range 1 GeV-1 TeV (ORCA). The expected maximum data rate is 200 Mbps per optical module. The implemented optical data transport system matches the layouts of the networks of electro-optical cables and junction boxes in the deep sea. For efficient use of the fibres in the system the technology of Dense Wavelength Division Multiplexing is applied. The performance of the optical system in terms of measured bit error rates, optical budget are presented. The next steps in the implementation of the system are also discussed
Searches for neutrinos in the direction of radio-bright blazars with the ANTARES telescope
Active galaxies, especially blazars, are among the most promising neutrino
source candidates. To date, ANTARES searches for these objects considered
GeV-TeV -ray bright blazars. Here, a statistically complete
radio-bright blazar sample is used as the target for searches of origins of
neutrinos collected by the ANTARES neutrino telescope over 13 years of
operation. The hypothesis of a neutrino-blazar directional correlation is
tested by pair counting and by a complementary likelihood-based approach. The
resulting post-trial -value is ( in the two-sided
convention), possibly indicating a correlation. Additionally, a time-dependent
analysis is performed to search for temporal clustering of neutrino candidates
as a mean of detecting neutrino flares in blazars. None of the investigated
sources alone reaches a significant flare detection level. However, the
presence of 18 sources with a pre-trial significance above indicates
a ( in the two-sided convention) detection of a
time-variable neutrino flux. An \textit{a posteriori} investigation reveals an
intriguing temporal coincidence of neutrino, radio, and -ray flares of
the J0242+1101 blazar at a ( in the two-sided convention)
level. Altogether, the results presented here suggest a possible connection of
neutrino candidates detected by the ANTARES telescope with radio-bright
blazars
The Control Unit of the KM3NeT Data Acquisition System
The KM3NeT Collaboration runs a multi-site neutrino observatory in the Mediterranean Sea. Water Cherenkov particle detectors, deep in the sea and far off the coasts of France and Italy, are already taking data while incremental construction progresses. Data Acquisition Control software is operating off-shore detectors as well as testing and qualification stations for their components. The software, named Control Unit, is highly modular. It can undergo upgrades and reconfiguration with the acquisition running. Interplay with the central database of the Collaboration is obtained in a way that allows for data taking even if Internet links fail. In order to simplify the management of computing resources in the long term, and to cope with possible hardware failures of one or more computers, the KM3NeT Control Unit software features a custom dynamic resource provisioning and failover technology, which is especially important for ensuring continuity in case of rare transient events in multi-messenger astronomy. The software architecture relies on ubiquitous tools and broadly adopted technologies and has been successfully tested on several operating systems
Limits on the nuclearite flux using the ANTARES neutrino telescope
In this work, a search for nuclearites of strange quark matter by using nine
years of ANTARES data taken in the period 2009-2017 is presented. The passage
through matter of these particles is simulated %according to the model of de
R\'{u}jula and Glashow taking into account a detailed description of the
detector response to nuclearites and of the data acquisition conditions. A
down-going flux of cosmic nuclearites with Galactic velocities () was considered for this study. The mass threshold for detecting these
particles at the detector level is \mbox{ GeV/c}.
Upper limits on the nuclearite flux for masses up to GeV/c at
the level of cm s sr are
obtained. These are the first upper limits on nuclearites established with a
neutrino telescope and the most stringent ever set for Galactic velocities.Comment: 17 pages, 7 figure
Search for magnetic monopoles with ten years of the ANTARES neutrino telescope
This work presents a new search for magnetic monopoles using data taken with the ANTARES neutrino telescope over a period of 10 years (January 2008 to December 2017). Compared to previous ANTARES searches, this analysis uses a run-by-run simulation strategy, with a larger exposure as well as a new simulation of magnetic monopoles taking into account the Kasama, Yang and Goldhaber model for their interaction cross-section with matter. No signal compatible with the passage of relativistic magnetic monopoles is observed, and upper limits on the flux of magnetic monopoles with β=v/c≥0.55, are presented. For ultra-relativistic magnetic monopoles the flux limit is ∼7×10−18 cm−2s−1sr−1
ANTARES search for point-sources of neutrinos using astrophysical catalogs: a likelihood stacking analysis
A search for astrophysical point-like neutrino sources using the data
collected by the ANTARES detector between January 29, 2007 and December 31,
2017 is presented. A likelihood stacking method is used to assess the
significance of an excess of muon neutrinos inducing track-like events in
correlation with the location of a list of possible sources. Different sets of
objects are tested in the analysis: a) a sub-sample of the \textit{Fermi} 3LAC
catalog of blazars, b) a jet-obscured AGN population, c) a sample of soft
gamma-ray selected radio galaxies, d) a star-forming galaxy catalog , and e) a
public sample of 56 very-high-energy track events from the IceCube experiment.
None of the tested sources shows a significant association with the sample of
neutrinos detected by ANTARES. The smallest p-value is obtained for the radio
galaxies catalog with an equal weights hypothesis, with a pre-trial p-value
equivalent to a excess, equivalent to
post-trial.
In addition, the results of a dedicated analysis for the blazar MG3
J225517+2409 are also reported: this source is found to be the most significant
within the \textit{Fermi} 3LAC sample, with 5 ANTARES events located at less
than one degree from the source. This blazar showed evidence of flaring
activity in \textit{Fermi} data, in space-time coincidence with a high-energy
track detected by IceCube. An \emph{a posteriori} significance of for the combination of ANTARES and IceCube data is reported
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