Abstract
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 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 (
β
= 10
-3
) was considered for this study. The mass threshold for detecting these particles at the detector level is 4 × 10
13
GeV/
c
2
. Upper limits on the nuclearite flux for masses up to 10
17
GeV/
c
2
at the level of ∼ 5 × 10
-17
cm
-2
s
-1
sr
-1
are obtained. These are the first upper limits on nuclearites established with a neutrino telescope and the most stringent ever set for Galactic velocities.
•A novel electromechanical structure is proposed for active ground motion isolation.•State of the art disturbance rejection at the subnanometer scale for heavy loads (up to 50kg) is achieved.•A 13dB ...attenuation of the ground motion is obtained between 12Hz and 100Hz.
Vibration isolation is a critical issue in various precision engineering fields. A new design of an active isolation system operating heavy loads (up to 50kg) is presented in this work. This system provides state of the art vibration isolation at the nanometer scale for magnets of a future particle accelerator and is more compact than other studies in this field. The choice of sensors and actuators, the mechanical design and the acquisition electronics are investigated in order to reject ground motion efficiently. A dynamic experimental characterization is performed. Based on the identified model, a specific controller, giving an attenuation between 10Hz and 100Hz was designed and experimentally qualified.
The KM3NeT multi-PMT optical module Alshamsi, M.; Alves Garre, S.; Aly, Z. ...
Journal of instrumentation,
07/2022, Letnik:
17, Številka:
7
Journal Article
Recenzirano
Odprti dostop
Abstract
The optical module of the KM3NeT neutrino telescope is an
innovative multi-faceted large area photodetection module. It
contains 31 three-inch photomultiplier tubes in a single 0.44 m
...diameter pressure-resistant glass sphere. The module is a sensory
device also comprising calibration instruments and electronics for
power, readout and data acquisition. It is capped with a
breakout-box with electronics for connection to an electro-optical
cable for power and long-distance communication to the onshore
control station. The design of the module was qualified for the
first time in the deep sea in 2013. Since then, the technology has
been further improved to meet requirements of scalability,
cost-effectiveness and high reliability. The module features a
sub-nanosecond timing accuracy and a dynamic range allowing the
measurement of a single photon up to a cascade of thousands of
photons, suited for the measurement of the Cherenkov radiation
induced in water by secondary particles from interactions of
neutrinos with energies in the range of GeV to PeV. A distributed
production model has been implemented for the delivery of more than
6000 modules in the coming few years with an average production rate
of more than 100 modules per month. In this paper a review is
presented of the design of the multi-PMT KM3NeT optical module with
a proven effective background suppression and signal recognition and
sensitivity to the incoming direction of photons.
Abstract
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.
The calibration units of KM3NeT Le Breton, R.; Billault, M.; Boutonnet, C. ...
Journal of instrumentation,
09/2021, Letnik:
16, Številka:
9
Journal Article
Recenzirano
Odprti dostop
KM3NeT is a deep-sea infrastructure composed of two neutrino telescopes being deployed in the Mediterranean Sea: ARCA, near Sicily in Italy, designed for neutrino astronomy, and ORCA, near Toulon in ...France, designed for neutrino oscillation physics. To achieve the best performance, the exact location of the optical modules, affected by sea current, must be known at any time and the timing resolution between optical modules must reach the nanosecond. Moreover, the properties of the environment in which the telescopes are deployed must be continuously monitored because they affect the timing and positioning calibration. KM3NeT is going to deploy several dedicated Calibration Units to meet these calibration goals. Because of the difference in size between ARCA and ORCA, the design of the Calibration Unit is not the same for the two sites. This proceeding describes all the devices, features and purposes of the Calibration Units with a focus on the ORCA Calibration Unit.
Abstract
The KM3NeT collaboration is currently deploying the first detection units of a neutrino observatory in the Mediterranean Sea, which, once completed, will be equipped with thousands of ...so-called digital optical modules. In addition to the detection units KM3NeT has designed an independent calibration unit, housing a set of calibration instruments, including e.g. an acoustic beacon and a laser beacon. The calibration unit and the embedded software developed to operate it are presented here.
Neutrino detectors participate in the indirect search for the fundamental constituents of dark matter (DM) in form of weakly interacting massive particles (WIMPs). In WIMP scenarios, candidate DM ...particles can pair-annihilate into Standard Model products, yielding considerable fluxes of high-energy neutrinos. A detector like ANTARES, located in the Northern Hemisphere, is able to perform a complementary search looking towards the Galactic Centre, where a high density of dark matter is thought to accumulate. Both this directional information and the spectral features of annihilating DM pairs are entered into an unbinned likelihood method to scan the data set in search for DM-like signals in ANTARES data. Results obtained upon unblinding 3170 days of data reconstructed with updated methods are presented, which provides a larger, and more accurate, data set than a previously published result using 2101 days. A non-observation of dark matter is converted into limits on the velocity-averaged cross section for WIMP pair annihilation.
ABSTRACT
Addressing the origin of the astrophysical neutrino flux observed by IceCube is of paramount importance. Gamma-Ray Bursts (GRBs) are among the few astrophysical sources capable of achieving ...the required energy to contribute to such neutrino flux through pγ interactions. In this work, ANTARES data have been used to search for upward going muon neutrinos in spatial and temporal coincidence with 784 GRBs occurred from 2007 to 2017. For each GRB, the expected neutrino flux has been calculated in the framework of the internal shock model and the impact of the lack of knowledge on the majority of source redshifts and on other intrinsic parameters of the emission mechanism has been quantified. It is found that the model parameters that set the radial distance where shock collisions occur have the largest impact on neutrino flux expectations. In particular, the bulk Lorentz factor of the source ejecta and the minimum variability time-scale are found to contribute significantly to the GRB-neutrino flux uncertainty. For the selected sources, ANTARES data have been analysed by maximizing the discovery probability of the stacking sample through an extended maximum-likelihood strategy. Since no neutrino event passed the quality cuts set by the optimization procedure, 90 per cent confidence level upper limits (with their uncertainty) on the total expected diffuse neutrino flux have been derived, according to the model. The GRB contribution to the observed diffuse astrophysical neutrino flux around 100 TeV is constrained to be less than 10 per cent.
The KM3NeT research infrastructure is under construction in the Mediterranean Sea. It consists of two water Cherenkov neutrino detectors, ARCA and ORCA, aimed at neutrino astrophysics and oscillation ...research, respectively. Instrumenting a large volume of sea water with
∼
6200
optical modules comprising a total of
∼
200
,
000
photomultiplier tubes, KM3NeT will achieve sensitivity to
∼
10
MeV
neutrinos from Galactic and near-Galactic core-collapse supernovae through the observation of coincident hits in photomultipliers above the background. In this paper, the sensitivity of KM3NeT to a supernova explosion is estimated from detailed analyses of background data from the first KM3NeT detection units and simulations of the neutrino signal. The KM3NeT observational horizon (for a
5
σ
discovery) covers essentially the Milky-Way and for the most optimistic model, extends to the Small Magellanic Cloud (
∼
60
kpc
). Detailed studies of the time profile of the neutrino signal allow assessment of the KM3NeT capability to determine the arrival time of the neutrino burst with a few milliseconds precision for sources up to 5–8 kpc away, and detecting the peculiar signature of the
standing accretion shock instability
if the core-collapse supernova explosion happens closer than 3–5 kpc, depending on the progenitor mass. KM3NeT’s capability to measure the neutrino flux spectral parameters is also presented.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
This letter presents a combined measurement of the energy spectra of atmospheric νe and νμ in the energy range between ∼100 GeV and ∼50 TeV with the ANTARES neutrino telescope. The analysis uses 3012 ...days of detector livetime in the period 2007–2017, and selects 1016 neutrinos interacting in (or close to) the instrumented volume of the detector, yielding shower-like events (mainly from νe+ν‾e charged current plus all neutrino neutral current interactions) and starting track events (mainly from νμ+ν‾μ charged current interactions). The contamination by atmospheric muons in the final sample is suppressed at the level of a few per mill by different steps in the selection analysis, including a Boosted Decision Tree classifier. The distribution of reconstructed events is unfolded in terms of electron and muon neutrino fluxes. The derived energy spectra are compared with previous measurements that, above 100 GeV, are limited to experiments in polar ice and, for νμ, to Super-Kamiokande.
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