Search Results (45)

Due to the Askaryan effect, radio emissions will be produced when ultra-high-energy (UHE) cosmic rays and neutrinos impact the lunar regolith. Many experiments have been proposed and performed to detect such radio emissions from the lunar regolith. However, none of the Cherenkov radio signals has been detected in these experiments up to now. In order to improve the detectability of the UHE particles, we proposed an experiment to carry out the radio observations of the UHE cosmic rays and neutrinos with two 30 m telescopes for a far longer time than the present experiments. The expected sensitivity for the detection of such UHE particles has been calculated, both for cosmic rays and neutrinos. The results show that a few UHE particle events above 10²⁰ eV could be detected with the expected observation time of several thousand hours. Full article

KM3NeT is an underwater neutrino detector currently under construction. Since the installation of its first detection unit in 2015, it has been continuously collecting data. Due to its complex design comprising a 3D array of sensors, an Acoustic Positioning System (APS) has been developed to monitor the position of each sensor. Given the increasing number of acoustic sensors used for the APS, both receivers and emitters, a solution has been implemented to check their status. In this contribution, a monitoring tool for this instrumentation is presented, capable of evaluating its status at both the data and operational levels. For effective monitoring, it is crucial to associate the signal recorded by a receiver with the corresponding transmitter. The Acoustic Data Filter (ADF) performs a cross-correlation between the signals retained in a buffer and those emitted by each installed emitter. It saves the maximum peak value and its associated time of arrival for each expected signal. However, the growing number of beacons complicates the differentiation of corresponding transmitters due to the huge amount of data recorded by the ADF needing post-processing. To address this challenge, a monitoring tool is developed that analyzes the internal clock of each emitter to distinguish and filter the data collected by the ADF. This tool has proven to be highly effective at verifying the correct operation of all acoustic devices deployed at sea. The acoustic monitoring graphical output produced for each data slot facilitates quick failure detection, enabling a swift response. Last but not least, the tool is modular and scalable, adapting to the addition or removal of sensors from the detector. Full article

Blazars—a subclass of active galaxies—are intrinsically time-variable broadband sources of electromagnetic radiation. In this contribution, we explored relativistic proton (hadronic) signatures in the time domain blazar emission and searched for those parameter combinations that unveil their presence during flaring epochs. We generated time series for key model parameters, like magnetic field strength and the power-law index of radiating particles, which were motivated from a simulated time series with statistical properties describing the observed GeV gamma-ray flux. We chose the TeV blazar Mrk 501 as our test case, as it had been the study ground for extensive investigations during individual flaring events. Using the code LeHaMoC, we computed the electromagnetic and neutrino emissions for a period of several years that contained several flares of interest. We show that for both of those particle distributions the power-law index variations that were tied to moderate changes in the magnetic field strength of the emitting region might naturally lead to hard X-ray flares with very-high-energy $\gamma$-ray counterparts. We found spectral differences measurable by the Cherenkov Telescope Array Observatory at sub-TeV energies, and we computed the neutrino fluence over 14.5 years. The latter predicted ∼0.2 muon and anti-muon neutrinos, consistent with the non-detection of high-energy neutrinos from Mrk 501. Full article

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 also includes 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 ten 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, which total 828 as of October 2023. In 2017, an upgrade of the power board, to increase reliability and efficiency, was initiated. The validation of a pre-production series has been completed, and 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 safe operation at the bottom of the Mediterranean Sea throughout the observatory’s lifespan. Full article

The development of the latest generation of Imaging Atmospheric Cherenkov Telescopes (IACTs) over recent decades has led to the discovery of new extreme astrophysical phenomena in the very-high-energy (VHE, E > 100 GeV) gamma-ray regime. Time-domain and multi-messenger astronomy are inevitably connected to the physics of transient VHE emitters, which show unexpected (and mostly unpredictable) flaring or exploding episodes at different timescales. These transients often share the physical processes responsible for the production of the gamma-ray emission, through cosmic-ray acceleration, magnetic reconnection, jet production and/or outflows, and shocks interactions. In this review, we present an up-to-date overview of the VHE transients field, spanning from novae to supernovae, neutrino counterparts or fast radio bursts, among others, and we outline the expectations for future facilities. Full article

Silicon Photomultipliers find applications across various fields. One potential Silicon Photomultiplier application domain is neutrino telescopes, where they may enhance the angular resolution. However, the elevated dark count rate associated with Silicon Photomultipliers represents a significant challenge to their widespread utilization. To address this issue, it is proposed to use Silicon Photomultipliers and Photomultiplier Tubes together. The Photomultiplier Tube signals serve as a trigger to mitigate the dark count rate, thereby preventing undue saturation of the available bandwidth. This paper presents an investigation into a fast and resource-efficient method for filtering the Silicon Photomultiplier dark count rate. A low-resource and fast coincident filter has been developed, which removes the Silicon Photomultiplier dark count rate by using as a trigger the Photomultiplier Tube input signals. The architecture of the coincidence filter, together with the first results obtained, which validate the effectiveness of this method, is presented. Full article

The origin of high-energy cosmic rays, and their behavior in astrophysical sources, remains an open question. Recently, new ways to address this question have been made possible by the observation of a new astrophysical messenger, namely neutrinos. The IceCube telescope has detected a diffuse flux of astrophysical neutrinos in the TeV-PeV energy range, likely produced in astrophysical sources accelerating cosmic rays, and more recently it has reported on a few candidate individual neutrino sources. Future experiments will be able to improve on these measurements quantitatively, by the detection of more events, and qualitatively, by extending the measurement into the EeV energy range. In this paper, we review the main features of the neutrino emission and sources observed by IceCube, as well as the main candidate sources that could contribute to the diffuse neutrino flux. As a parallel question, we review the status of high-energy neutrinos as a probe of Beyond the Standard Model physics coupling to the neutrino sector. Full article

NUSES is a pathfinder satellite project hosting two detectors: Ziré and Terzina. Ziré focuses on the study of protons and electrons below 250 MeV and MeV gamma rays. Terzina is dedicated to the detection of Cherenkov light produced by ultra-high-energy cosmic rays above 100 PeV and ultra-high-energy Earth-skimming neutrinos in the atmosphere, ensuring a large exposure. This work mainly concerns the description of the Cherenkov camera, composed of SiPMs, for the Terzina telescope. To increase the data-taking period, the NUSES orbit will be Sun-synchronous (with a height of about 550 km), thus allowing Terzina to always point toward the dark side of the Earth’s limb. The Sun-synchronous orbit requires small distances to the poles, and as a consequence, we expect an elevated dose to be received by the SiPMs. Background rates due to the dose accumulated by the SiPM would become a dominant contribution during the last two years of the NUSES mission. In this paper, we illustrate the measured effect of irradiance on SiPM photosensors with a variable-intensity beam of 50 MeV protons up to a 30 Gy total integrated dose. We also show the results of an initial study conducted without considering the contribution of solar wind protons and with an initial geometry with Geant4. The considered geometry included an entrance lens as one of the options in the initial design of the telescope. We characterize the SiPM output signal shape with different μ-cell sizes. We describe the developed parametric SiPM simulation, which is a part of the full Terzina simulation chain. Full article

Following the breakthrough discoveries of very-high-energy neutrinos of astrophysical origin by IceCube, a new field of research, neutrino astronomy, was established in the previous decade. Even though two extragalactic point sources of such neutrinos have been identified by now, TXS 0506+056 and NGC 1068, the origin and processes of the creation of astrophysical neutrinos are still mostly unexplored. To advance quickly in this new field, more neutrino telescopes are needed. This article describes the current status and plans for the development of the Pacific Ocean Neutrino Experiment (P-ONE), which is under construction in the Pacific Ocean near Vancouver Island. The deployment of P-ONE is expected to start in 2025, exploiting the already available deep-sea infrastructure provided by Ocean Networks Canada. P-ONE will complement the existing IceCube, Baikal-GVD, and KM3NeT neutrino telescopes not only with its large detection volume, but also by providing insight into the southern celestial hemisphere, where the central region of the Galactic Plane is located. Full article

Numerous studies suggest that high-energy (HE) neutrinos and ultra-high-energy (UHE) cosmic rays could originate from extremely high-synchrotron peaked (EHSP) BL Lacs, which have been identified as effective particle accelerators. Due to the discovery of HE-neutrinos by the IceCube telescope, these hypotheses may shortly have the opportunity to be tested. In this work, we use a two-zone leptohadronic model to explain the spatial coincidence of three EHSP BL Lac: 1RXS J09462.5+010459, 1ES 1101-232, and 3HSP J095507.9+355101 with the arrival of track-like neutrinos. Our results for 1RXS J09462.5+010459 and 1ES 1101-232 indicate that the model accurately describes the electromagnetic emission and neutrino events without increasing the fluxes in the measured bands. In addition, the X-ray flaring state of 3HSP J095507.9+355101 can be explained by our model, but the measured ultraviolet flux during the neutrino arrival time window cannot be explained. For all cases, the broadband emission and neutrino arrival are better described by hard proton distributions ≈1.5. Finally, the proton luminosity required to explain the neutrino fluxes is slightly higher than the Eddington limit with a photopion efficiency of ≈0.1 for non-flaring state cases. On the other hand, for the flaring state of 3HSP J095507.9+355101, the proton luminosity must be higher than the Eddington limit at least by one order of magnitude, even if the photopion efficiency reaches unity. Full article

Although there is overwhelming evidence for the existence of dark matter, the nature of dark matter remains largely unknown. Neutrino telescopes are powerful tools to search indirectly for dark matter, through the detection of neutrinos produced during dark matter decay or annihilation processes. The IceCube Neutrino Observatory is a cubic-kilometer-scale neutrino telescope located under 1.5 km of ice near the Amundsen-Scott South Pole Station. Various dark matter searches were performed with IceCube over the last decade, providing strong constraints on dark matter models. In this contribution, we present the latest results from IceCube as well as ongoing analyses using IceCube data, focusing on the works that look at the Galactic Halo, nearby galaxies, and galaxy clusters. Full article

NUSES is a planned space mission aiming to test new observational and technological approaches related to the study of relatively low-energy cosmic rays, gamma rays, and high-energy astrophysical neutrinos. Two scientific payloads will be hosted onboard the NUSES space mission: Terzina and Zirè. Terzina will be an optical telescope readout by SiPM arrays, for the detection and study of Cerenkov light emitted by Extensive Air Showers generated by high-energy cosmic rays and neutrinos in the atmosphere. Zirè will focus on the detection of protons and electrons up to a few hundred MeV and to 0.1–10 MeV photons and will include the Low Energy Module (LEM). The LEM will be a particle spectrometer devoted to the observation of fluxes of relatively low-energy electrons in the 0.1–7-MeV range and protons in the 3–50 MeV range along the Low Earth Orbit (LEO) followed by the hosting platform. The detection of Particle Bursts (PBs) in this Physics channel of interest could give new insight into the understanding of complex phenomena such as eventual correlations between seismic events or volcanic activity with the collective motion of particles in the plasma populating van Allen belts. With its compact sizes and limited acceptance, the LEM will allow the exploration of hostile environments such as the South Atlantic Anomaly (SAA) and the inner Van Allen Belt, in which the anticipated electron fluxes are on the order of ${10}^6$ to ${10}^7$ electrons per square centimeter per steradian per second. Concerning the vast literature of space-based particle spectrometers, the innovative aspect of the LEM resides in its compactness, within 10 × 10 × 10 cm³, and in its “active collimation” approach dealing with the problem of multiple scattering at these very relatively low energies. In this work, the geometry of the detector, its detection concept, its operation modes, and the hardware adopted will be presented. Some preliminary results from the Monte Carlo simulation (Geant4) will be shown. Full article

Core-collapse supernovae (SNe) are one of the most powerful cosmic sources of neutrinos, with energies of several MeV. The emission of neutrinos and antineutrinos of all flavors carries away the gravitational binding energy of the compact remnant and drives its evolution from the hot initial to the cold final states. Detecting these neutrinos from Earth and analyzing the emitted signals present a unique opportunity to explore the neutrino mass ordering problem. This research outlines the detection of neutrinos from SNe and their relevance in understanding the neutrino mass ordering. The focus is on developing a model-independent analysis strategy, achieved by comparing distinct detection channels in large underground detectors. The objective is to identify potential indicators of mass ordering within the neutrino sector. Additionally, a thorough statistical analysis is performed on the anticipated neutrino signals for both mass orderings. Despite uncertainties in supernova explosion parameters, an exploration of the parameter space reveals an extensive array of models with significant sensitivity to differentiate between mass orderings. The assessment of various observables and their combinations underscores the potential of forthcoming supernova observations in addressing the neutrino mass ordering problem. Full article

This paper encapsulates details of the NEMO laser beacon’s design, offering a profound contribution to the field of the time calibration of underwater neutrino telescopes. The mechanical design of the laser beacon, which operates at a depth of 3500 m, is presented, together with the design of the antibiofouling system employed to endure the operational pressure and optimize the operational range, enhancing its functionality and enabling time calibration among multiple towers. A noteworthy innovation central to this development lies in the battery system. This configuration enhances the device’s portability, a crucial aspect in underwater operations. The comprehensive design of the laser beacon, encompassing the container housing, the requisite battery system for operation, electronics, and an effective antibiofouling system, is described in this paper. Additionally, this paper presents the findings of the laser beacon’s qualification process. Full article

The cubic-kilometre neutrino telescope (KM3NeT) is a piece of deep-sea infrastructure composed of two neutrino telescopes consisting of large-scale 3D arrays of photomultiplier tubes (PMTs). KM3NeT is currently under construction on the Mediterranean seabed. The two telescopes are ARCA, near Sicily, which is designed for neutrino astronomy, and ORCA, near Toulon, France, designed for measurement of neutrino oscillations. The ORCA telescope, having a neutrino energy threshold in the GeV range, has as its main research goal the measurement of the neutrino mass ordering and atmospheric neutrino oscillation parameters. In this paper, we discuss the calibration procedures which are necessary to achieve these purposes. Full article