89 research outputs found
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
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
Routes for Efficient Computational Homogenization of Nonlinear Materials Using the Proper Generalized Decompositions
Computational homogenization is nowadays one of the most active research topics in computational mechanics. Different strategies have been proposed, the main challenge being the computing cost induced by complex microstructures exhibiting nonlinear behaviors. Two quite tricky scenarios lie in (i) the necessity of applying the homogenization procedure for many microstructures (e.g. material microstructure evolving at the macroscopic level or stochastic microstructure); the second situation concerns the homogenization of nonlinear behaviors implying the necessity of solving microscopic problems for each macroscopic state (history independent nonlinear models) or for each macroscopic history (history dependant non-linear models). In this paper we present some preliminary results concerning the application of Proper Generalized Decompositions for addressing the efficient solution of homogenization problems. This numerical technique could allow to compute the homogenized properties for any microstructure or for any macroscopic loading history by solving a single but highly multidimensional model. The PGD allows circumventing the so called curse of dimensionality that mesh based representations suffer. Even if this work only describes the firs steps in a very ambitious objective , many original ideas are launched that could be at the origin of impressive progresses
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