Home » Blog

KM3NeT - Blog

KM3NeT blog posts

A set of dedicated studies on KM3-230213A

20 February 2025 – Recently the KM3NeT Collaboration has published evidence for the cosmic neutrino with the highest energy ever detected (the article on Nature can be accessed from here). This event is identified as KM3-230213A.

In a set of dedicated studies, the Collaboration has investigated the possible sources of the event and the implications that may be derived from it.

These studies are included in a set of articles which have recently been released:

The ultra-high-energy event KM3-230213A within the global neutrino landscape

The compatibility of the occurrence of KM3-230213A with the constraints placed by other experiments is explored.

Read the full article here: https://arxiv.org/abs/2502.08173

On the Potential Galactic Origin of the Ultra-High-Energy Event KM3-230213A

The possibility that KM3-230213A may have originated in our Galaxy is discussed. The study did not allow to identify plausible mechanisms and sources which could sustain such hypothesis, leading to the conclusion that the neutrino is most likely of extra-Galactic origin.

Read the full article here: https://arxiv.org/abs/2502.08387

Characterising Candidate Blazar Counterparts of the Ultra-High-Energy Event KM3-230213A

In this paper the possibility is explored that KM3-230213A may have originated in a distant blazar. The study concerned a set of 17 blazars, which were identified as plausible sources of high-energy neutrinos due to their multiwavelength properties, highlighting in particular three of them. This work involved plenty of facilities: KM3NeT, VLA, VLBA, RATAN-600, OVRO, Swift, Fermi, SRG/eROSITA, Gaia, CRTS, ATLAS, ZTF, WISE/NEOWISE, Chandra and ROSAT!

Read the full article here: https://arxiv.org/abs/2502.08484

On the potential cosmogenic origin of the ultra-high-energy event KM3-230213A

The intriguing possibility that KM3-230213A may be of cosmogenic origin, i.e. it was originated from the interaction of ultra-high-energy cosmic rays with ambient photon and matter fields, is discussed in this paper, leading to hypotheses for reconciling the occurrence of this event with the latest measurements of cosmic rays of extreme energy.

Read the full article here: https://arxiv.org/abs/2502.08508

KM3NeT Constraint on Lorentz-Violating Superluminal Neutrino Velocity

The Lorentz symmetry, the fundamental principle which states that nothing can go faster than the speed of light in vacuum, is tested in this study. By looking at the energy of KM3-230213A and the distance travelled, the difference between neutrino and light speed was constrained to less than 1 part in 1000 billion billion, which represents the most stringent limit ever set using this method of analyzing high-energy neutrinos.

Read the full article here: https://arxiv.org/abs/2502.08508

Limits on the violation of the Lorentz principle (see the article for full details)

The observation of an ultra-high-energy cosmic neutrino at the bottom of the sea

KM3NeT Popular Information – 12/02/2025

Unveiling the Universe Through Ultra-High-Energy Neutrinos

When we think of the universe, images of stars, galaxies, and vast expanses of darkness come to mind. Yet, hidden within this cosmic expanse are invisible messengers—neutrinos— tiny particles that can travel unimpeded from the furthest reaches of the universe.

On the 12th of February, 2025, scientists working on the Kilometre cube Neutrino Telescope (KM3NeT) in the Mediterranean Sea have published in Nature the observation of an extraordinary event: the evidence of an ultra-high-energy cosmic neutrino, shedding new light on some of the Universe’s most energetic processes.

What are neutrinos?

Neutrinos are subatomic particles with no electric charge and an incredibly small mass. They are elusive, interacting so weakly with matter that billions of them pass through us every second without a trace. Produced in a huge range of energies, and in many different processes – from large amount of low energy neutrinos produced in nuclear fusion processes in our Sun, to small amount of high energy neutrinos coming from particle collisions in cataclysmic cosmic events such as exploding stars or black hole activity – neutrinos are unique because their path remains undisturbed . This allows them to act as cosmic messengers, carrying information directly from their astrophysical source to detectors on Earth.

One module of KM3NeT with 31 light sensitive ‘eyes’ (called photomultiplier tubes) in the deep sea. The observatory which detected the ultra-high energy event (called KM3NeT/ARCA) had 378 of such modules installed at the time of the detection, on a total of 21 vertical detection lines attached to the sea bottom. The lines are at almost 100 meters distance from one another, and are almost 700 meters long. Altogether being a huge network of light sensitive ‘eyes’. Courtesy KM3NeT.

Detecting neutrinos requires giant observatories for example located deep underwater or in ice. These observatories look for faint flashes of Cherenkov light—a luminous glow created when charged particles produced by neutrino interactions move faster than light in the medium. The KM3NeT telescope located deep in the Mediterranean Sea is one such observatory, designed to catch high-energy neutrino events via these flashes of light.

A record-breaking discovery

On February 13, 2023, the KM3NeT team recorded a neutrino event unlike any other. Named KM3-230213A, the neutrino’s energy was estimated to be an astonishing 220 peta- electronvolts (PeV) – roughly a billion times 100 million times the energy of visible light photons and about 30 times the highest neutrino energy previously detected.

The event occurred in KM3NeT’s ARCA detector, located 3450 meters underwater near Sicily in Italy. KM3NeT/ARCA is designed to study high-energy neutrinos, while its sister detector KM3NeT/ORCA, located near Toulon in France, focuses on lower-energy neutrinos. During this event, the detector’s photomultiplier tubes recorded over 28 000 photons of light produced while the charged particle coming from the neutrino interaction crossed the entire detector.

What makes this event special?

The detection of KM3-230213A is ground-breaking for several reasons:

Unprecedented Energy: Such high-energy neutrinos are extremely rare, making this a monumental discovery.
Precision Detection: The advanced design of the ARCA detector, featuring multi- photomultiplier optical modules with nanosecond timing precision, enabled precise reconstruction of the neutrino’s trajectory and energy. Its near-horizontal path through the detector indicates a cosmic origin, as atmospheric muons cannot travel such long distances through the seawater without being absorbed.
Cosmic Origins: This neutrino might originate from a powerful cosmic accelerator, such as an active galactic nucleus or a gamma-ray burst. Alternatively, it could be a cosmogenic neutrino, produced in the interaction between an ultra-high-energy cosmic ray with the background radiation in the universe.

Searching for the source

After detecting KM3-230213A, the KM3NeT scientists analysed its direction and energy to identify its possible astrophysical origin. Researchers cross-referenced data from gamma-ray, X-ray, and radio telescopes to look for potential counterparts, such as blazars or transient events. While its arrival direction aligns with regions containing active cosmic phenomena, no definitive source could be significantly identified.

Visual impression of the ultra-high energy neutrino event observed in KM3NeT/ARCA. The colours indicate the light seen by the ‘eyes’ on each module, where the different colours represent different observation times. The almost horizontally reconstructed track of the particle is shown as a line from right to left. Courtesy KM3NeT.

Even though an extragalactic origin is most likely, the event’s position near the Galactic plane does not exclude the possibility it originated in our Milky Way.

This highlights the challenge of linking single neutrino detections to specific astrophysical sources.

Its importance for neutrino astronomy

This discovery marks a milestone in neutrino astronomy, a field still in its infancy compared to traditional optical or radio astronomy. High-energy neutrino observations like KM3- 230213A offer unique insights into the most extreme environments in the universe. They may help answer long-standing questions about the origins of cosmic rays and how they can be accelerated to such enormous energies.

Furthermore, KM3-230213A provides valuable data to refine models of cosmic neutrino production and propagation. It also demonstrates the capabilities of next-generation observatories like KM3NeT, which continue to push the boundaries of our understanding.

The road ahead

While KM3-230213A raises many questions, it also opens new doors. Future observations will focus on detecting more such events to build a clearer picture of their origins. The ongoing expansion of KM3NeT with additional detection lines and increasing data taking time will improve its sensitivity and enhance its ability to pinpoint neutrino sources.

The evidence of this ultra-high-energy cosmic neutrino is a testament to human ingenuity and the enduring quest to understand the universe. Each neutrino captured is like a piece of a jigsaw puzzle, revealing a bit more about the cosmos. As technology advances, we are poised to discover even more extraordinary phenomena in the vast expanse of space.

A fruitful Collaboration Meeting in Louvain-la-Neuve!

4 February 2025 – Last week, KM3NeT has met, both in person and online, for its winter Collaboration Meeting , in Louvain-la-Neuve, Belgium, hosted by UCLouvain.

Various discussions and presentations highlighted progresses and activities related to the ARCA and ORCA detectors, including updates on construction, simulation, calibration and data analysis efforts. The meeting also featured talks on the latest scientific results, including…plans for very exciting results to be announced soon!

Beyond the scientific sessions, the event fostered community engagement through social activities and networking opportunities.

It was also the occasion to welcome our new Management Team: Paul De Jong (Nikhef and University of Amsterdam, The Netherlands) serves as Spokesperson, Damien Dornic (CPPM/CNRS, France) as Deputy Spokesperson, Rosa Coniglione (INFN-LNS, Italy) as the Physics and Software Manager, and Antonio D’Amico (Nikhef, The Netherlands) holds the position of Technical Project Manager. The entire Collaboration extends its congratulations to the outgoing Management Team and wishes the best of luck to its newly elected members.

The KM3Net Collaboration is pleased to welcome a new team, from INFN and University of Florence, Italy, coordinated by Nicola Mori: we are happy to have you as part of our Collaboration and look forward to your valuable contributions.

Thanks a lot to the whole local team for the wonderful organization.

The next Collaboration Meeting is scheduled for the coming summer, in France, at Caen.

The KM3NeT Management team (from left to right): Damien Dornic, Paul De Jong, Rosa Coniglione and Antonio D’Amico.

The KM3NeT Collaboration has elected a new Management Team!

13 December 2024 – During the last Collaboration meeting, the KM3NeT Collaboration has elected a new Management Team, who will serve for the two coming years. In addition to the new Institute Board Chair, prof Antoine Kouchner from UPCité, France elected last June, the following people will be leading the Collaboration as:

Spokesperson: Paul De Jong (Nikhef and University of Amsterdam, The Netherlands)
Deputy Spokesperson: Damien Dornic (CPPM/CNRS, France)
Physics and Software Manager: Rosa Coniglione (INFN-LNS, Italy)
Technical Project Manager: Antonio D’Amico (Nikhef, The Netherlands)

The transition from the current to the new Management Team will happen at the next Collaboration meeting at the end of January, celebrated with presents and pictures! Stay tuned!

Curious about who are the people behind the researchers? We asked them to share a few words about themselves!

Paul De Jong – Spokesperson:

“I studied Applied Physics at the Twente University of Technology in Enschede, the Netherlands, and did my PhD at Nikhef and at the University of Amsterdam in the ZEUS collaboration at the HERA collider at DESY in 1993, on calorimeter construction and reconstruction software, and measurement of the hadronic energy flow in first HERA data.

I was then a postdoc in the L3 Collaboration at LEP, first employed by MIT, later as a CERN fellow, on the commissioning of, and track reconstruction software for, the newly installed endcap muon chambers on the L3 magnet doors. I worked on the Z-line shape in dimuon decays and on W physics (triple gauge couplings and mass) at LEP 2. I returned to Nikhef in 1999 with a sponsored tenure-track position, joined D0 at the Tevatron (electron reconstruction and top physics) and ATLAS at the LHC, where I spent most time, in construction of the silicon strip detector endcaps and their commissioning, and in searches for supersymmetry in ATLAS data.

I got tenure at Nikhef in 2003, was appointed professor at the University of Amsterdam (UvA) in 2008, and full professor in 2012; I served as the director of the (astro)particle physics division (IHEF) of the UvA Institute of Physics between 2015 and 2024, and as director of the full UvA Institute of Physics between 2017 and 2022. I have handed over the Nikhef KM3NeT group leadership to Dorothea Samtleben last year, and the directorship of IHEF to someone else this summer.

With KM3NeT we have embarked on an amazing project. It resonates with everyone I talk to, from the general public to students to people at funding agencies. We have employed more than 50 detection units and produced first results, and the discoveries coming not only show how well the detector works, but also how much there is still to explore in our field.”

Fun fact about Paul: He was member of the Particle Data Group where he co-authored several instances of the Review on Experimental SUSY Searches in the Particle Data Book!

Damien Dornic – Deputy Spokesperson:

“I began my career as PhD student at the Pierre Auger Observatory before joining the ANTARES and KM3NeT collaborations in 2006, where I pursued two postdoctoral positions, first at CPPM in Marseille and then at IFIC in Valencia. In 2011, I was appointed a permanent research position at CNRS. During this period, I have acquired expertise in neutrino astronomy. I was coordinator of the multi-messenger analysis group in ANTARES between 2012 and 2017 and coordinator of the multi-messenger and transient analysis group in KM3NeT between 2017 and 2020. Between 2020 and 2025, I was the co-convener of the astronomy group of KM3NeT. I am also in charge of the implementation of the real-time analysis framework in KM3NeT. I have been a pioneer in the development of the neutrino follow-up program of ANTARES and have developed collaborations with plenty of international observatories.

Fun fact about Damien: Beyond his work in neutrino astronomy, Damien is also involved in the construction of the ORCA detector, contributing to technical discussions and the integration of detection units!

Rosa Coniglione – Physics and Software Manager:

“In the first part of my career, I worked on experimental nuclear physics, spending many years developing and operating an apparatus to study heavy-ion collisions. A seminar at my institute opened up a new world for me: I was captivated by a new, at least for me, detector that employed particle physics technology to explore the cosmos. Inspired by this idea, I began my work with KM3NeT.

Since the inception of the Collaboration, I have dedicated all my time to KM3NeT. I contributed to the ARCA detector design through MC simulations and participated in the initial sensitivity estimates. For many years, I led the Astronomy group and oversaw data analysis since the early stages of the Collaboration (first for the prototype detection units and then during the initial phase of construction of the apparatus). I have served as the Deputy Spokesperson of the Collaboration for the past four years.”

Fun fact about Rosa: Despite being born in Sicily, she worked for many years in France before joining KM3NeT. She is as passionate about Paris as about neutrinos!

Antonio D’Amico – Technical Project Manager:

“My engagement with KM3NeT started in the early stages of the project and consisted of developing an optical transmission system for a future submarine neutrino detector. During the following 10 years, I was involved in the design of the various detector prototypes, along with their installation and commissioning.

Since 2011, I have been part of the design team of the optics work package, which I later coordinated from 2018 to 2022 as a member of the Project Steering Committee. During the same period, I have been responsible for the design, validation, procurement, installation, and commissioning of the optical transmission system of KM3NeT Phase 1.

Starting in 2019, the structure of the project coordination has been experiencing profound changes with the full establishment of the Project Office team, in which I was appointed as Project Control Officer (PCO) in 2022.”

Fun fact about Antonio: Antonio has been a member of KM3NeT since his master thesis, learning from, growing with and now leading the Collaboration!

KM3NeT welcomes newcomers at the 2024 Bootcamp

10 December 2024 – The KM3NeT Bootcamp 2024, held at the Erlangen Centre for Astroparticle Physics – ECAP, took place last week, bringing together 56 enthusiastic participants from around the world in a hybrid format. Over four engaging days, the attendees, guided by 18 expert teachers, dived into the fundamentals of KM3NeT, gaining insights into its core principles and tools.

The agenda included foundational sessions on the KM3NeT collaboration and detector principles, as well as hands-on workshops in software development, data acquisition, simulations, and calibration. Advanced topics covered astronomy, cosmic rays, neutrino oscillations, and the study of dark matter. Participants also explored tools for effective coding, data quality and computing strategies.

This event served as more than an introduction—it welcomed newcomers into the KM3NeT community, inspiring them to contribute to the future of science.

We extend our heartfelt thanks to ECAP for their exceptional organization and support in hosting this event.

Here’s to the next generation of cosmic explorers!

KM3NeT gathered online for its fall collaboration meeting

13 November 2024 – Last week , the KM3NeT Collaboration has met online for its fall meeting.

During the meeting, we reviewed the current status of data taking for both ARCA and ORCA detectors, discussed the advancements in their construction, the progresses in MC simulation and detector calibration, and outlined the plans for the ongoing data analyses.

It was also the occasion to celebrate our two last sea campaigns and thus the expanded configurations of the detectors, ARCA 33 and ORCA24. The deployment of new instrumentation on the ORCA site will allow for a precise monitoring of the detector position and water properties.

During the meeting Antoine Kouchner started his mandate as chairperson of the Institute Board, taking over from Uli Katz: with many thanks to Uli for all the work done in the past years, and good luck to Antoine for his new duty.

Also during the meeting, the process to elect the new Management Team of the Collaboration was started.

Finally, KM3NeT gave a heartfelt greeting to its new members. Juan Antonio Aguilar Sánchez of the Université Libre de Bruxelles, Belgium, and Elisa Bernardini of Padova University, Italy, joined as Observers, while the team led by Arthur Ukleja from the University of Krakow, Poland, was endorsed as Full Member.

A warm welcome to everyone!

It was great to see the advancements in the physics analyses as well as the simulation and calibration works, to discuss recent scientific advancements and to see the Collaboration continue to grow.

The next Collaboration Meeting is scheduled for January, in Belgium, at Louvain-la-Neuve.

Welcome ARCA33 and ORCA24!

28 October 2024 – The latest sea campaigns at both the KM3NeT’s ARCA and ORCA sites have led to major progress in expanding detector installations and improving calibration systems.

The number of detection units in operation in the deep sea has been increased to 57: 33 in ARCA and 24 in ORCA.

Despite bad weather at the ARCA site, the so-called Phase-1 part of the apparatus was completed, while construction of Phase-2 was started with the installation of two new junction boxes, three detection units (exploiting a new data acquisition architecture), and calibration components. The operations also included important maintenance tasks, such as recovering and replacing acoustic beacons. All optical modules of the deployed strings are fully operational. KM3NeT/ARCA now comprises 33 detection units.

At the ORCA site, a 60-hour calm weather window allowed the team to deploy the Calibration Unit (Calibration Base+Instrumentation Unit) and to install an additional detection unit. After these successful installations, node 1 of ORCA is complete and fully functional, an important milestone in the construction of ORCA. The total number of functional detection units at ORCA has now reached 24.

These recent efforts at both sites underscore KM3NeT’s expanding capability in detecting and studying neutrinos from the sea’s depths. The whole Collaboration extends its gratitude to the offshore and onshore teams whose hard work made these successful operations possible.

A furled detection unit ready for the deployment at the ORCA site

ORCA offshore team on the Castor 02 ship

Components for ARCA on the deck of the Optimus Prime ship: in the foreground is one junction box, behind it there are a couple of spools with the submarine interlink cables and then some detection units

ARCA onshore shift crew at the site of Portopalo

ATLAS comet visible from the harbour of Portopalo di Capo Passero

Sonar scan of the ORCA site taken by the ROV at the end of the operation. The anchors of the detections Units (DUs), the junction box (JB1), the Calibration Base (CB), the Instrumentation Unit (IU) and the Module Instrumentation Interface (MII) are all visible.

Neutrino 2024 Poster Winner: Isabel Goos

03 July 2024 – In June, KM3NeT scientist participated to the XXXI International Conference on Neutrino Physics and Astrophysics (Neutrino 2024), held in Milan, Italy, and organized by the University of Milano – Bicocca, the University of Milan and the Istituto Nazionale di Fisica Nucleare (INFN).

As one of the largest conferences in astroparticle physics, neutrino physics and cosmology, it was the occasion to share latest findings, innovative concepts and future outlooks among experts of the field.

Isabel Goos at Neutrino 2024 (credits Neutrino2024)

During the conference, Isabel Goos, KM3NeT’s researcher at the University of Paris Cité, was awarded one of the four prizes for the best-poster award. In her poster, titled “KM3NeT’s sensitivity to the next core-collapse supernova”, she discusses how individual multi-PMT optical modules of KM3NeT can be used as standalone detectors for the detection of low-energy neutrinos from Core Collapsed Super Novae. It has been selected among 460 accepted posters, of which 319 eligible for this acknowledgement.

KM3NeT joins in congratulating Isabel on her great achievement!

In total, KM3NeT presented 17 posters, covering topics including neutrino astronomy, neutrino oscillations, dark matter & exotics, cosmic-ray studies and technologies for neutrino physics.

In addition, four members of the KM3NeT Collaboration had a plenary talk: João Coelho, who discussed the latests results from KM3NeT; Maurizio Spurio, debating open problems in neutrino astrophysics; Naoko Kurahashi Neilson, contributing on the present and future of high-energy neutrino astronomy, and Jürgen Brunner presenting future detectors for atmospheric neutrinos.

Neutrino 2026 will be held at the University of California – Irvine. Looking forward to sharing our advancements also on that occasion!

The KM3NeT Collaboration reunited in Texel for its spring meeting

23 June 2024 – KM3NeT has met, in Texel (The Netherlands) and online, for its spring Collaboration meeting, hosted by NIOZ, the Royal Netherlands Institute for Sea Research.

The meeting brought together collaborators in order to review the status of the ongoing analyses, Monte Carlo simulations and calibration efforts, for both the ARCA and ORCA detectors, and prepare exciting contributions to the Neutrino 2024 Conference.

During the week, the progress of detector construction was discussed, celebrating the achievement of assembling the 1,500th DOM. Additionally, plans for upcoming sea campaigns were refined.

Furthermore, Antoine Kouchner has been elected chair of the KM3NeT Institute Board, taking over from Uli Katz. The full Collaboration joins in thanking Uli for his outstanding work and wishes the best of luck to Antoine for the incoming endeavors!

The meeting was also the opportunity to welcome the new members of the Collaboration. Both the Max Planck Institute for Radio Astronomy (Bonn, Germany) and the Khalifa University (United Arab Emirates) have been endorsed as Full Members, with Yuri Y. Kovalev and Satyendra Thoudam as PIs respectively. Kristina Giesel from ECAP Erlangen (Germany) joined as a new Associated Member. Welcome to all of you!

It was wonderful to engage in fruitful discussions about recent scientific developments and to see the Collaboration continue to grow.

Thanks a lot to NIOZ for the hospitality and to the whole local team for the organization!

The next meeting is scheduled for late autumn in online mode.

ORCA enlarged with four new detection units

15 June 2024 – A new marine operation took place in the last week for enlarging the ORCA deep-sea neutrino telescope.

Taking advantage of a spot of good weather of 48 hours, four new detection units were added to the apparatus.

For each of such units, the following steps were required: installation on the bottom of the sea, connection to the apparatus, functionality check, unfurling from the launcher vehicle, final test to check the functionality post-unfurling and recovery of the launcher vehicle. During the operation one acoustic beacon, which was in need of refurbishment, was recovered from the bottom of the sea.

The campaign was performed with two ships and a deep-sea ROV. A team onshore performed all needed tests on the newly installed detection units.

After the new installations, ORCA now comprises 23 detection units; only one more detection unit is needed for completing all connections on the first of the submarine nodes of the apparatus.

Many thanks to all teams involved for this important step forward!