21 research outputs found
Higher-precision radial velocity measurements with the SOPHIE spectrograph using octagonal-section fibers
High-precision spectrographs play a key role in exoplanet searches using the
radial velocity technique. But at the accuracy level of 1 m.s-1, required for
super-Earth characterization, stability of fiber-fed spectrograph performance
is crucial considering variable observing conditions such as seeing, guiding
and centering errors and, telescope vignetting. In fiber-fed spectrographs such
as HARPS or SOPHIE, the fiber link scrambling properties are one of the main
issues. Both the stability of the fiber near-field uniformity at the
spectrograph entrance and of the far-field illumination on the echelle grating
(pupil) are critical for high-precision radial velocity measurements due to the
spectrograph geometrical field and aperture aberrations. We conducted tests on
the SOPHIE spectrograph at the 1.93-m OHP telescope to measure the instrument
sensitivity to the fiber link light feeding conditions: star decentering,
telescope vignetting by the dome,and defocussing.
To significantly improve on current precision, we designed a fiber link
modification considering the spectrograph operational constraints. We have
developed a new link which includes a piece of octagonal-section fiber, having
good scrambling properties, lying inside the former circular-section fiber, and
we tested the concept on a bench to characterize near-field and far-field
scrambling properties.
This modification has been implemented in spring 2011 on the SOPHIE
spectrograph fibers and tested for the first time directly on the sky to
demonstrate the gain compared to the previous fiber link. Scientific validation
for exoplanet search and characterization has been conducted by observing
standard stars.Comment: 12 pages, 9 figures, Proceedings of SPIE 201
Dependence of atmospheric muon flux on seawater depth measured with the first KM3NeT detection units: The KM3NeT Collaboration
KM3NeT is a research infrastructure located in the Mediterranean Sea, that will consist of two deep-sea Cherenkov neutrino detectors. With one detector (ARCA), the KM3NeT Collaboration aims at identifying and studying TeVâPeV astrophysical neutrino sources. With the other detector (ORCA), the neutrino mass ordering will be determined by studying GeV-scale atmospheric neutrino oscillations. The first KM3NeT detection units were deployed at the Italian and French sites between 2015 and 2017. In this paper, a description of the detector is presented, together with a summary of the procedures used to calibrate the detector in-situ. Finally, the measurement of the atmospheric muon flux between 2232â3386Â m seawater depth is obtained
Deep-sea deployment of the KM3NeT neutrino telescope detection units by self-unrolling
KM3NeT is a research infrastructure being installed in the deep Mediterranean Sea.
It will house a neutrino telescope comprising hundreds of networked moorings â detection units
or strings â equipped with optical instrumentation to detect the Cherenkov radiation generated
by charged particles from neutrino-induced collisions in its vicinity. In comparison to moorings
typically used for oceanography, several key features of the KM3NeT string are different: the
instrumentation is contained in transparent and thus unprotected glass spheres; two thin DyneemaÂź
ropes are used as strength members; and a thin delicate backbone tube with fibre-optics and copper
wires for data and power transmission, respectively, runs along the full length of the mooring. Also,
compared to other neutrino telescopes such as ANTARES in the Mediterranean Sea and GVD in
Lake Baikal, the KM3NeT strings are more slender to minimise the amount of material used for
support of the optical sensors. Moreover, the rate of deploying a large number of strings in a period
of a few years is unprecedented. For all these reasons, for the installation of the KM3NeT strings,
a custom-made, fast deployment method was designed. Despite the length of several hundreds of
metres, the slim design of the string allows it to be compacted into a small, re-usable spherical
launching vehicle instead of deploying the mooring weight down from a surface vessel. After
being lowered to the seafloor, the string unfurls to its full length with the buoyant launching vehicle
rolling along the two ropes. The design of the vehicle, the loading with a string, and its underwater
self-unrolling are detailed in this paper.French National Research Agency (ANR)
ANR-15-CE31-0020Centre National de la Recherche Scientifique (CNRS)European Union (EU)Institut Universitaire de France (IUF)LabEx UnivEarthS
ANR-10-LABX-0023
ANR-18-IDEX-0001Paris Ile-de-France Region, FranceShota Rustaveli National Science Foundation of Georgia (SRNSFG), Georgia
FR-18-1268German Research Foundation (DFG)Greek Ministry of Development-GSRTIstituto Nazionale di Fisica Nucleare (INFN), Ministero dell'Universita e della Ricerca (MUR), PRIN Italy
NAT-NET 2017W4HA7SMinistry of Higher Education, Scientific Research and Professional Training, MoroccoNetherlands Organization for Scientific Research (NWO)
Netherlands GovernmentNational Science Center, Poland
National Science Centre, Poland
2015/18/E/ST2/00758National Authority for Scientific Research (ANCS), RomaniaMinisterio de Ciencia, InnovaciĂłn, InvestigaciĂłn y Universidades (MCIU): Programa Estatal de GeneraciĂłn de Conocimiento (MCIU/FEDER)
PGC2018-096663-B-C41
PGC2018-096663-B-A-C42
PGC2018-096663-B-BC43
PGC2018-096663-B-B-C44Severo Ochoa Centre of Excellence and MultiDark Consolider (MCIU), Junta de AndalucĂa
SOMM17/6104/UGRGeneralitat Valenciana
GRISOLIA/2018/119
CIDEGENT/2018/034La Caixa Foundation
LCF/BQ/IN17/11620019EU: MSC program, Spain
71367
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
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
Technical Design Report of the MEUST Infrastructure
MEUST (Mediterranean Eurocentre for Underwater Sciences and Technologies) is a second generation permanent submarine observatory to be deployed offshore of Toulon, France, as a follow up of the pioneering ANTARES neutrino telescope. The MEUST submarine network has a modular topology designed to connect up to 120 neutrino detection units,i.e. ten times more than ANTARES. This may allow to instrument one km3 of water for neutrino astronomy or, with a denser instrumentation, several Megatons for measurement of neutrino properties, and to deploy sensors for environmental sciences on an array of ten km. The topology and functionalities of the network comply with the specifications of the KM3NeT neutrino telescope, which plans to use MEUST as one of its 3 deployment sites, as well as with those of the environmental sensors developed for the Ligurian site of the EMSO submarine observatory network. The technical solutions developed for the MEUST infrastructure are adapted to any large deep sea detector array located within 50 km from the coast. After a brief reminder of the MEUST scientific motivation and submarine sensors, this document details the technical design of the infrastructure and summarizes the organization of the project
Probing invisible neutrino decay with KM3NeT-ORCA
International audienceIn 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
Probing invisible neutrino decay with KM3NeT-ORCA
International audienceIn 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