Abstract
This paper presents a quantum efficiency measurement setup based on a 2D motorized stage, a wide spectrum xenon lamp, a beam splitter system, and two calibrated photo-diodes for measuring ...the quantum efficiency (QE) of photomultiplier tubes (1 to 10 inches).
We will demonstrate the effectiveness of technical refinements on the measurements procedures over some existing setups already shown in literature.
The large area covered by the 2D stages permit to study the quantum efficiency of PMTs with diameter up to ten inches.
The results obtained will show the high precision and accuracy in characterizing the quantum efficiency versus wavelength over the range of 250 nm to 1100 nm and along the photo-catode surface. The setup monitors the light intensity synchronously with the output current yield from photosensors under test. This ensures the accuracy and repeatability of the measurements. The motorized stage allows precise positioning of the light source with respect to the active area. The emission spectrum of the xenon lamp provides a broad range of illumination in terms of dynamics and wavelength span.
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.
Abstract
The expectation for detecting with the KM3NeT/ARCA telescope, signals from Starburst Galaxies, both as diffuse signal and as point-like excess, is presented. A recent theoretical model was ...used for the diffused flux. The model, which has been developed by authors of this contribution, takes into account a “blending” of spectral indices to describe the spectral energy distribution. For the point-like search approach, the most promising local starburst galaxies to be observed as point-like neutrino excesses were considered: NGC 1068, the Small Magellanic Cloud and the Circinus Galaxy. For the diffuse analysis, the sensitivity for two ARCA building blocks is provided, considering both track and shower events, in the range of 100GeV − 100PeV. For the point-like analysis, the sensitivity for two ARCA building blocks is provided considering only track events. ARCA has the potential to constrain the selected phenomenological scenarios, showing the minimum of the sensitivity where the theoretical spectral energy distributions are expected to peak. This could provide evidence of the link between star-forming processes and hadronic emissions.
The ANTARES detector is at present the most sensitive neutrino telescope in the northern hemisphere. The highly significant cosmic neutrino excess observed by the Antarctic IceCube detector can be ...studied with ANTARES, exploiting its complementing field of view, exposure, and lower energy threshold. Searches for an all-flavor diffuse neutrino signal, covering nine years of ANTARES data taking, are presented in this Letter. Upward-going events are used to reduce the atmospheric muon background. This work includes for the first time in ANTARES both track-like (mainly and shower-like (mainly ) events in this kind of analysis. Track-like events allow for an increase of the effective volume of the detector thanks to the long path traveled by muons in rock and/or sea water. Shower-like events are well reconstructed only when the neutrino interaction vertex is close to, or inside, the instrumented volume. A mild excess of high-energy events over the expected background is observed in nine years of ANTARES data in both samples. The best fit for a single power-law cosmic neutrino spectrum, in terms of per-flavor flux at 100 TeV, is 10−18 GeV−1 cm−2 s−1 sr−1 with spectral index . The null cosmic flux assumption is rejected with a significance of 1.6 .
The results of three different searches for neutrino candidates, associated with the IceCube-170922A event or from the direction of TXS 0506+056, by the ANTARES neutrino telescope, are presented. The ...first search refers to the online follow-up of the IceCube alert; the second is based on the standard time-integrated method employed by the Collaboration to search for point-like neutrino sources; the third uses information from the IceCube time-dependent analysis that reported bursting activity centered on 2014 December 13, as input for an ANTARES time-dependent analysis. The online follow-up and the time-dependent analysis yield no events related to the source. The time-integrated study performed over a period from 2007 to 2017 fits 1.03 signal events, which corresponds to a p-value of 3.4% (not considering trial factors). Only for two other astrophysical objects in our candidate list has a smaller p-value been found. When considering that 107 sources have been investigated, the post-trial p-value for TXS 0506+056 corresponds to 87%.
Abstract
Gamma-ray bursts are thought to be sites of hadronic acceleration, thus neutrinos are expected from the decay of charged particles, produced in pγ interactions. The methods and results of a ...search for muon neutrinos in the data of the ANTARES neutrino telescope from four bright GRBs (GRB 080916C, GRB 110918A, GRB 130427A and GRB 130505A) observed between 2008 and 2013 are presented. Two scenarios of the fireball model have been investigated: the internal shock scenario, leading to the production of neutrinos with energies mainly above 100 TeV, and the photospheric scenario, characterized by a low-energy component in neutrino spectra due to the assumption of neutrino production closer to the central engine. Since no neutrino events have been detected in temporal and spatial coincidence with these bursts, upper limits at 90 per cent confidence level on the expected neutrino fluxes are derived. The non-detection allows for directly constraining the bulk Lorentz factor of the jet Γ and the baryon loading fp.
Abstract
On 2019 October 1, the IceCube Collaboration detected a muon track neutrino with a high probability of being of astrophysical origin, IC191001A. After a few hours, the tidal disruption event ...(TDE) AT2019dsg, observed by the Zwicky Transient Facility (ZTF), was indicated as the most likely counterpart of the IceCube track. More recently, the follow-up campaign of the IceCube alerts by ZTF suggested a second TDE, AT2019fdr, as a promising counterpart of another IceCube muon track candidate, IC200530A, detected on 2020 May 30. Here, these intriguing associations are followed-up by searching for neutrinos in the ANTARES detector from the directions of AT2019dsg and AT2019fdr using a time-integrated approach. As no significant evidence for space clustering is found in the ANTARES data, upper limits on the one-flavor neutrino flux and fluence are set.
Abstract
Since 2015 the LIGO and Virgo interferometers have detected gravitational waves from
almost one hundred coalescences of compact objects (black holes and neutron stars). This article
presents ...the results of a search performed with data from the ANTARES telescope to identify
neutrino counterparts to the gravitational wave sources detected during the third LIGO/Virgo
observing run and reported in the catalogues GWTC-2, GWTC-2.1, and GWTC-3. This search is
sensitive to all-sky neutrinos of all flavours and of energies > 100 GeV,
thanks to the inclusion of both track-like events (mainly induced by
ν
μ
charged-current
interactions) and shower-like events (induced by other interaction types). Neutrinos are selected
if they are detected within ± 500 s from the GW merger and with a reconstructed
direction compatible with its sky localisation. No significant excess is found for any of the 80
analysed GW events, and upper limits on the neutrino emission are derived. Using the information
from the GW catalogues and assuming isotropic emission, upper limits on the total energy
E
tot,
ν
emitted as neutrinos of all flavours and on the ratio
f
ν
=
E
tot,
ν
/
E
GW
between neutrino and GW emissions are also computed. Finally, a stacked
analysis of all the 72 binary black hole mergers (respectively the 7 neutron star-black hole
merger candidates) has been performed to constrain the typical neutrino emission within this
population, leading to the limits:
E
tot,
ν
< 4.0 × 10
53
erg and
f
ν
< 0.15
(respectively,
E
tot,
ν
< 3.2 × 10^53 erg and
f
ν
< 0.88) for
E
-2
spectrum
and isotropic emission. Other assumptions including softer spectra and non-isotropic scenarios
have also been tested.
In the past decade, a new class of bright transient radio sources with millisecond duration has been discovered. The origin of these so-called fast radio bursts (FRBs) is still a mystery, despite the ...growing observational efforts made by various multiwavelength and multimessenger facilities. To date, many models have been proposed to explain FRBs, but neither the progenitors nor the radiative and the particle acceleration processes at work have been clearly identified. In this paper, we assess whether hadronic processes may occur in the vicinity of the FRB source. If they do, FRBs may contribute to the high-energy cosmic-ray and neutrino fluxes. A search for these hadronic signatures was carried out using the ANTARES neutrino telescope. The analysis consists in looking for high-energy neutrinos, in the TeV–PeV regime, that are spatially and temporally coincident with the detected FRBs. Most of the FRBs discovered in the period 2013–2017 were in the field of view of the ANTARES detector, which is sensitive mostly to events originating from the Southern hemisphere. From this period, 12 FRBs were selected and no coincident neutrino candidate was observed. Upper limits on the per-burst neutrino fluence were derived using a power-law spectrum, dN/dEν∝E−γν, for the incoming neutrino flux, assuming spectral indexes γ = 1.0, 2.0, 2.5. Finally, the neutrino energy was constrained by computing the total energy radiated in neutrinos, assuming different distances for the FRBs. Constraints on the neutrino fluence and on the energy released were derived from the associated null results
Muons created by charged current (CC) interactions in the water surrounding the ANTARES neutrino telescope have been almost exclusively used so far in searches for cosmic neutrino sources. Due to ...their long range, highly energetic muons inducing Cherenkov radiation in the water are reconstructed with dedicated algorithms that allow for the determination of the parent neutrino direction with a median angular resolution of about 0 4 for an neutrino spectrum. In this paper, an algorithm optimized for accurate reconstruction of energy and direction of shower events in the ANTARES detector is presented. Hadronic showers of electrically charged particles are produced by the disintegration of the nucleus both in CC and neutral current interactions of neutrinos in water. In addition, electromagnetic showers result from the CC interactions of electron neutrinos while the decay of a tau lepton produced in CC interactions will, in most cases, lead to either a hadronic or an electromagnetic shower. A shower can be approximated as a point source of photons. With the presented method, the shower position is reconstructed with a precision of about 1 m; the neutrino direction is reconstructed with a median angular resolution between 2° and 3° in the energy range of 1-1000 TeV. In this energy interval, the uncertainty on the reconstructed neutrino energy is about 5%-10%. The increase in the detector sensitivity due to the use of additional information from shower events in the searches for a cosmic neutrino flux is also presented.
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