Cherenkov Neutrino Telescope Research Articles

Differential Sensitivity of the KM3NeT/ARCA detector to a diffuse neutrino flux and to point-like source emission: Exploring the case of the Starburst Galaxies

KM3NeT/ARCA is a Cherenkov neutrino telescope under construction in the Mediterranean sea, optimised for the detection of astrophysical neutrinos with energies above ∼1 TeV. In this work, using Monte Carlo simulations including all-flavour neutrinos, the integrated and differential sensitivities for KM3NeT/ARCA are presented considering the case of a diffuse neutrino flux as well as extended and point-like neutrino sources. This analysis is applied to Starburst Galaxies demonstrating that the detector has the capability of tracing TeV neutrinos from these sources. Remarkably, after eight years, a hard power-law spectrum from the nearby Small Magellanic Cloud can be constrained. The sensitivity and discovery potential for NGC 1068 is also evaluated showing that KM3NeT/ARCA will discriminate between different astrophysical components of the measured neutrino flux after 3 years of data taking.

Discovery potential of the Glashow resonance in an air shower neutrino telescope* *Project Supported by the ``CUG Scholar'' Scientific Research Funds at China University of Geosciences (Wuhan) (2024014)

The in-ice or in-water Cherenkov neutrino telescope, such as IceCube, has already proved its power in measuring the Glashow resonance by searching for the bump around arising from the W-boson production. There are many proposals for the next few decades for observations of cosmic tau neutrinos with extensive air showers, also known as tau neutrino telescopes. The air shower telescope is, in principle, sensitive to the Glashow resonance via the channel followed by the tau decay in the air (e.g., TAMBO, which has a geometric area of approximately ). Using a thorough numerical analysis, we find that the discovery significance can be up to 90% with a TAMBO-like setup if PeV neutrinos primarily originate from neutron decays, considering the flux parameters measured by IceCube as the input. The presence of new physics affecting the neutrino flavor composition can also increase the significance. However, if ultrahigh-energy neutrinos are dominantly produced from meson decays, it will be statistically difficult for an advanced proposal such as TAMBO to discriminate the Glashow resonance induced by from the intrinsic background. We have identified several limitations for such advanced telescopes, in comparison with the in-ice or in-water telescope, when measuring resonances: (i) a suppressed branching ratio of 11% for the decay ; (ii) the smearing effect and reduced acceptance because the daughter neutrino takes away 75% of the energy from the W decay; and (iii) a large attenuation effect for Earth-skimming neutrinos with the resonance.

Calibration Facility for Detector Strings for the KM3NeT/ARCA Neutrino Telescope at the Capacity Laboratory

KM3NeT is a network of submarine Cherenkov neutrino telescopes under construction at two different sites in the Mediterranean Sea. ARCA, near Sicily in Italy, is optimised for the detection of cosmic neutrinos while ORCA, near Toulon in France, is optimized for atmospheric neutrinos. ARCA and ORCA are both arrays of thousands of optical sensors (Digital Optical Modules - DOMs), each consisting of 31 small photomultipliers (PMTs) housed inside a glass sphere, which detect the Cherenkov light produced by the secondary particles generated in the neutrino interactions. 18 DOMs are arranged on flexible strings, referred to as vertical Detection Units (DUs), anchored to the sea floor. Once completed, ARCA and ORCA will consist of 230 and 115 DUs, respectively. Each DOM of a string communicates at a dedicated wavelength to the shore station via a network of optical fibers transmitting optical and acoustic signal information as well as orientation information. Before the deployment, each DU is tested and calibrated in a dark room. The test bench is equipped with a full data acquisition system for communication, data processing, and time synchronisation. Several steps are needed to accomplish the DU calibration, including the High-Voltage (HV) tuning of the PMTs, checking of the acoustic receivers and calibration light sources in the DOM, and time calibration using laser signals distributed to all DOMs. Here, we describe the DU test and calibration facility at the CAPACITY laboratory (Campania AstroPArtiCle InfrastrucTure facilitY) in Caserta, focusing on the functional tests and calibrations performed at the end of the DU integration.

Simulation study on the optical processes at deep-sea neutrino telescope sites

The performance of a large-scale water Cherenkov neutrino telescope relies heavily on the transparency of the surrounding water, quantified by its level of light absorption and scattering. A pathfinder experiment was carried out to measure the optical properties of deep seawater in South China Sea with light-emitting diodes (LEDs) as light sources, photon multiplier tubes (PMTs) and cameras as photon sensors. Here, we present an optical simulation program employing the Geant4 toolkit to understand the absorption and scattering processes in the deep seawater, which helps to extract the underlying optical properties from the experimental data. The simulation results are compared with the experimental data and show good agreements. We also verify the analysis methods that utilize various observables of the PMTs and the cameras with this simulation program, which can be easily adapted by other neutrino telescope pathfinder experiments and future large-scale detectors.

Determining the neutrino mass ordering and oscillation parameters with KM3NeT/ORCA

The next generation of water Cherenkov neutrino telescopes in the Mediterranean Sea are under construction offshore France (KM3NeT/ORCA) and Sicily (KM3NeT/ARCA). The KM3NeT/ORCA detector features an energy detection threshold which allows to collect atmospheric neutrinos to study flavour oscillation. This paper reports the KM3NeT/ORCA sensitivity to this phenomenon. The event reconstruction, selection and classification are described. The sensitivity to determine the neutrino mass ordering was evaluated and found to be 4.4sigma if the true ordering is normal and 2.3sigma if inverted, after 3 years of data taking. The precision to measure varDelta m^2_{32} and theta _{23} were also estimated and found to be 85 . 10^{-6}~{mathrm{eV}^{2}} and (^{+1.9}_{-3.1})^{circ } for normal neutrino mass ordering and, 75 . 10^{-6}~{mathrm{eV}^{2}} and (^{+2.0}_{-7.0})^{circ } for inverted ordering. Finally, a unitarity test of the leptonic mixing matrix by measuring the rate of tau neutrinos is described. Three years of data taking were found to be sufficient to exclude event rate variations larger than 20% at 3sigma level.

LeptonInjector and LeptonWeighter: A neutrino event generator and weighter for neutrino observatories

We present a high-energy neutrino event generator, called LeptonInjector, alongside an event weighter, called LeptonWeighter. Both are designed for large-volume Cherenkov neutrino telescopes such as IceCube. The neutrino event generator allows for quick and flexible simulation of neutrino events within and around the detector volume, and implements the leading Standard Model neutrino interaction processes relevant for neutrino observatories: neutrino-nucleon deep-inelastic scattering and neutrino-electron annihilation. In this paper, we discuss the event generation algorithm, the weighting algorithm, and the main functions of the publicly available code, with examples. Program summaryProgram Titles:LeptonInjector and LeptonWeighterCPC Library link to program files:https://doi.org/10.17632/662gkpjfd9.1Developer's repository links:https://github.com/icecube/LeptonInjector and https://github.com/icecube/LeptonWeighterLicensing provisions: GNU Lesser General Public License, version 3.Programming Language: C++11External Routines:•Boost•HDF5•nuflux (https://github.com/icecube/nuflux)•nuSQuIDS (https://github.com/arguelles/nuSQuIDS)•Photospline (https://github.com/icecube/photospline)•SuiteSparse (https://github.com/DrTimothyAldenDavis/SuiteSparse)Nature of problem:LeptonInjector: Generate neutrino interaction events of all possible topologies and energies throughout and around a detector volume.LeptonWeighter: Reweight Monte Carlo events, generated by a set of LeptonInjector Generators, to any desired physical neutrino flux or cross section.Solution method:LeptonInjector: Projected ranges of generated leptons and the extent of the detector, in terms of column depth, are used to inject events in and around the detector volume. Event kinematics follow distributions provided in cross section files.LeptonWeighter: Event generation probabilities are calculated for each Generator, which are then combined into a generation weight and used to calculate an overall event weight.

Status and first results from the ARCA and ORCA lines of the KM3NeT experiment

KM3NeT is a network of submarine Cherenkov neutrino telescopes under construction in two different sites in the Mediterranean Sea [1]. The detector at the Italian site, close to the Sicilian coast and named ARCA, will be devoted to the detection of high-energy astrophysical neutrinos coming from sources in the Universe, while the detector at the French site, in the Toulon bay and named ORCA, will exploit atmospheric neutrinos to determine the neutrino mass hierarchy. The telescopes are an array of flexible strings anchored to the sea floor and held close to vertical by submerged buoys. The strings are instrumented with digital optical modules hosted within pressure-resistant glass spheres, each housing 31 3” photomultipliers tubes and the readout electronics. The geometry of the detectors has been adapted to their physics goals. The first calibrations and results of ARCA and ORCA are presented.

Acoustic Detection of Neutrinos: Review and Future Potential

The acoustic neutrino detection technique is a promising approach for future large-scale detectors with the aim of measuring the small expected flux of cosmogenic neutrinos at energies exceeding 100 PeV. The technique is based on the thermo-acoustic model, which implies that the energy deposition by a particle cascade—resulting from a neutrino interaction in a medium with suitable thermal and acoustic properties—leads to a local heating and a subsequent characteristic pressure pulse that propagates in the surrounding medium. The main advantage of using sound for the detection of neutrino interactions, as opposed to Cherenkov light, lies in the much longer attenuation length of the former type of radiation: several kilometres for sound compared to several ten metres for light in the respective frequency ranges of interest in sea water. As detection media for future detectors, water, ice, salt domes and permafrost have been discussed, but it is the first two which have been investigated most thoroughly by using existing arrays of acoustic receivers—mainly military arrays in various bodies of water—or by implementing dedicated acoustic arrays in Cherenkov neutrino telescopes. Such arrays have been installed in IceCube at the South Pole, in the Lake Baikal experiment in Siberia and in ANTARES and the former NEMO experiment in the Mediterranean Sea. The future KM3NeT neutrino telescope to be installed in the Mediterranean Sea will be equipped with acoustic sensors for position calibration that are suited to also serve acoustic detection purposes. Ongoing experiments in water and ice have established the feasibility of the acoustic neutrino detection technique and allowed for the investigation of prevailing background conditions. Methods to improve the signal detection efficiency and to reduce the rate of misidentified neutrinos have been devised and potential future large-scale detector designs are investigated using detailed simulations in combination with the wealth of collected experimental data. In this presentation, a brief review of acoustic particle detection, considering both theoretical and experimental aspects, will be given. The current status and plans for the future will be discussed.

Dark Matter Searches with the ANTARES Neutrino Telescope

The ANTARES Collaboration is operating the largest water Cherenkov neutrino telescope in the Northern hemisphere, installed in the Mediterranean Sea. One of the objectives of ANTARES is the search for neutrinos produced in self-annihilation of Dark Matter particles. The results on the search for Dark Matter annihilations in the Sun and in the Galactic Centre with the data recorded between 2007 and 2012 are presented. The search on the Sun has resulted in competitive limits on the WIMP-proton cross-section, and they are compared to the ones of other indirect and direct detection experiments as well as to predictions of SUSY models. Results of ANTARES on Dark Matter searches towards the Galactic Centre have concluded with competitive limits on the annihilation cross-sections for high mass WIMPs that disfavours the interpretation of the PAMELA electron/positron excesses (constrained by Fermi-LAT and H.E.S.S.) as a signal from dark matter self-annihilations.

Recent Results of the ANTARES Neutrino Telescope

The discovery of cosmic neutrinos of astrophysical origin by IceCube has started a new chapter in the field of Neutrino Astronomy. Noticeably, a small accumulation of events in the region near the Galactic Centre has been observed: a telescope in the Mediterranean Sea constitutes a great opportunity for the physics quest, since it offers a perfect complementarity to IceCube and, in particular, a better visibility of the Galactic Centre. ANTARES (Astronomy with a Neutrino Telescope and Abyss Environmental RESearch) is the first operational Cherenkov neutrino telescope in the Mediterranean Sea and the largest neutrino detector in the Northern hemisphere, covering an area of about 0.1 km2; located 40 km offshore Toulon, France, at a depth of 2475 m, it has been completed in June 2008 and it is currently taking data. It consists of a tri-dimensional array of 885 photo-multipliers tubes (PMTs), distributed in 12 lines. ANTARES has recently performed a search for an excess of high energy neutrinos in the direction of the Galactic Centre, close to the accumulation of the IceCube events, assuming both the hypotheses of a point-like and an extended neutrino source. The results of this search will be discussed in this contribution, together with other recent achievements of the experiment, as the search for point-like sources, the results on the diffuse flux of cosmic neutrino signal and the search for neutrino emission from the Fermi bubbles. ANTARES offers a first view of the Neutrino Sky from the Northern hemisphere; its successful operation and its promising results make more compelling the expectations for KM3NeT, the next generation neutrino experiment in the Mediterranean Sea.

Acoustic neutrino detection investigations within ANTARES and prospects for KM3NeT

The acoustic neutrino detection technique is a promising approach for future large-scale detectors with the aim of measuring the small expected flux of cosmogenic neutrinos at energies exceeding 1 EeV. It suggests itself to investigate this technique in the context of underwater Cherenkov neutrino telescopes, in particular KM3NeT, because acoustic sensors are present by design to allow for the calibration of the positions of the optical sensors. For the future, the KM3NeT detector in the Mediterranean Sea will provide an ideal infrastructure for a dedicated array of acoustic sensors. In this presentation results from the acoustic array AMADEUS of the ANTARES detector will be discussed with respect to the potential and implications for acoustic neutrino detection with KM3NeT and beyond.

The Trigger and Data Acquisition System for the 8 tower subsystem of the KM3NeT detector

KM3NeT is a deep-sea research infrastructure being constructed in the Mediterranean Sea. It will host a large Cherenkov neutrino telescope that will collect photons emitted along the path of the charged particles produced in neutrino interactions in the vicinity of the detector. The philosophy of the DAQ system of the detector foresees that all data are sent to shore after a proper sampling of the photomultiplier signals. No off-shore hardware trigger is implemented and a software selection of the data is performed with an on-line Trigger and Data Acquisition System (TriDAS) to reduce the large throughput due to the environmental light background. A first version of the TriDAS has been developed to operate a prototype detection unit deployed in March 2013 in the abyssal site of Capo Passero (Sicily, Italy), about 3500m deep. A revised and improved version has been developed to meet the requirements of the final detector, using new tools and modern design solutions. First installation and scalability tests have been performed at the Bologna Common Infrastructure and results comparable to what expected have been observed.

Hadronic flares and associated neutrinos for Markarian 421

AbstractMarkarian 421 (Mrk 421) is one of the brightest, fastest and closest BL Lac objects known. Its very high energy (VHE) spectrum has been successfully modeled with both leptonic and hadronic models and no conclusive results have been achieved yet about the origin of its VHE emission. Here we investigate the possibility that a fraction of the VHE flares of Mrk 421 are due to hadronic processes and calculate the expected associated neutrino flux. We introduce the obtained neutrino flux in a Monte Carlo simulation to see the expectation for a km3 Cherenkov neutrino telescope.

The KM3NeT deep-sea neutrino telescope

KM3NeT is a deep-sea research infrastructure being constructed in the Mediterranean Sea. It will host the next generation Cherenkov neutrino telescope and nodes for a deep sea multidisciplinary observatory, providing oceanographers, marine biologists, and geophysicists with real time measurements. The neutrino telescope will complement IceCube in its field of view and exceed it substantially in sensitivity. Its main goal is the detection of high energy neutrinos of astrophysical origin. The detector will have a modular structure with six building blocks, each consisting of about 100 Detection Units (DUs). Each DU will be equipped with 18 multi-PMT digital optical modules. The first phase of construction has started and shore and deep-sea infrastructures hosting the future KM3NeT detector are being prepared in offshore Toulon, France and offshore Capo Passero on Sicily, Italy. The technological solutions for the neutrino detector of KM3NeT and the expected performance of the neutrino telescope are presented and discussed.

Status of the KM3NeT project

KM3NeT is a deep-sea research infrastructure being constructed in the Mediterranean Sea. It will be installed at three sites: KM3NeT-Fr, offshore Toulon, France, KM3NeT-It, offshore Portopalo di Capo Passero, Sicily (Italy) and KM3NeT-Gr, offshore Pylos, Peloponnese, Greece. It will host the next generation Cherenkov neutrino telescope and nodes for a deep sea multidisciplinary observatory, providing oceanographers, marine biologists, and geophysicists with real time measurements. The neutrino telescope will search for Galactic and extra-Galactic sources of neutrinos, complementing IceCube in its field of view. The detector will have a modular structure and consists of six building blocks, each including about one hundred Detection Units (DUs). Each DU will be equipped with 18 multi-PMT digital optical modules. The first phase of construction has started and shore and deep-sea infrastructures hosting the future KM3NeT detector are being prepared in France near Toulon and in Italy, near Capo Passero in Sicily. The technological solutions for KM3NeT and the expected performance of the detector are presented and discussed.

RECENT DEVELOPMENTS IN ULTRA-HIGH ENERGY NEUTRINO ASTRONOMY

We outline the current situation in ultrahigh energy (UHE) cosmic ray physics, pointing out the remaining problems, in particular the puzzle concerning the origin of the primary radiation and the role of neutrino astronomy for locating the sources. Various methods for the detection of UHE neutrinos are briefly described and their merits compared. We give an account of the achievements of the existing optical Cherenkov neutrino telescopes, outline the possibility of using air fluorescence and particle properties of air showers to identify neutrino induced events, and discuss various pioneering experiments employing radio and acoustic detection of extremely energetic neutrinos. The next generation of space, ground and sea based neutrino telescopes now under construction or in the planning phase are listed.

RECENT DEVELOPMENTS IN ULTRA-HIGH ENERGY NEUTRINO ASTRONOMY

We outline the current situation in ultrahigh energy (UHE) cosmic ray physics, pointing out the remaining problems, in particular the puzzle concerning the origin of the primary radiation and the role of neutrino astronomy for locating the sources. Various methods for the detection of UHE neutrinos are briefly described and their merits compared. We give an account of the achievements of the existing optical Cherenkov neutrino telescopes, outline the possibility of using air fluorescence and particle properties of air showers to identify neutrino induced events, and discuss various pioneering experiments employing radio and acoustic detection of extremely energetic neutrinos. The next generation of space, ground and sea based neutrino telescopes now under construction or in the planning phase are listed.

Neutrino detection, position calibration and marine science with acoustic arrays in the deep sea

Arrays of acoustic receivers are an integral part of present and potential future Cherenkov neutrino telescopes in the deep sea. They measure the positions of individual detector elements which vary with time as an effect of undersea currents. At the same time, the acoustic receivers can be employed for marine science purposes, in particular for monitoring the ambient noise environment and the signals emitted by the fauna of the sea. And last but not least, they can be used for studies towards acoustic detection of ultra-high-energy neutrinos. Measuring acoustic pressure pulses in huge underwater acoustic arrays with an instrumented volume of the order of 100km3 is a promising approach for the detection of cosmic neutrinos with energies exceeding 1EeV. Pressure signals are produced by the particle cascades that evolve when neutrinos interact with nuclei in water, and can be detected over large distances in the kilometre range. In this article, the status of acoustic detection will be reviewed and plans for the future – most notably in the context of KM3NeT – will be discussed. The connection between neutrino detection, position calibration and marine science will be illustrated.

Acoustic calibration for the KM3NeT pre-production module

The proposed large scale Cherenkov neutrino telescope KM3NeT will carry photo-sensors on flexible structures, the detection units. The Mediterranean Sea, where KM3NeT will be installed, constitutes a highly dynamic environment in which the detection units are constantly in motion. Thus it is necessary to monitor the exact sensor positions continuously to achieve the desired resolution for the neutrino telescope. A common way to perform this monitoring is the use of acoustic positioning systems with emitters and receivers based on the piezoelectric effect. The acoustic receivers are attached to detection units whereas the emitters are located at known positions on the sea floor. There are complete commercial systems for this application with sufficient precision. But these systems are limited in the use of their data and inefficient as they were designed to perform only this single task. Several working groups in the KM3NeT consortium are cooperating to custom-design a positioning system for the specific requirements of KM3NeT. Most of the studied solutions hold the possibility to extend the application area from positioning to additional tasks like acoustic particle detection or monitoring of the deep-sea acoustic environment. The KM3NeT Pre-Production Module (PPM) is a test system to verify the correct operation and interoperability of the major involved hardware and software components developed for KM3NeT. In the context of the PPM, alternative designs of acoustic sensors including small piezoelectric elements equipped with preamplifiers inside the same housing as the optical sensors will be tested. These will be described in this article.

The Antares computing model

Completed in 2008, Antares is now the largest water Cherenkov neutrino telescope in the Northern Hemisphere. Its main goal is to detect neutrinos from galactic and extra-galactic sources. Due to the high background rate of atmospheric muons and the high level of bioluminescence, several on-line and off-line filtering algorithms have to be applied to the raw data taken by the instrument. To be able to handle this data stream, a dedicated computing infrastructure has been set up.The paper covers the main aspects of the current official Antares computing model. This includes an overview of on-line and off-line data handling and storage. In addition, the current usage of the “IceTray” software framework for Antares data processing is highlighted. Finally, an overview of the data storage formats used for high-level analysis is given.