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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!

Update of gSeaGen simulation software

23 November 2024 – In a new paper with the title ‘gSeaGen code by KM3NeT: an efficient tool to propagate muons simulated with CORSIKA’ we describe an open source solution for efficient simulation of cosmic-ray induced muons in neutrino telescopes.

For this, we adapted the gSeaGen code, which generates high statistic samples of simulated neutrino-induced events, detectable by neutrino telescopes.

Updated gSeaGen can now also process muons from cosmic-ray induced particle showers in the atmosphere, which are generated by the Monte Carlo simulation code CORSIKA.

The tracking of muons towards the simulated detector offers efficient re-use of the particle shower when a muon misses the detector. We added several other new functionalities for computational efficiency and user control.

We updated gSeaGen with KM3NeT in mind, but other under-ground, under-water, or under-ice experiments may profit from it as well.

The paper is submitted to Computer Physics Communications
A preprint is available at: https://arxiv.org/abs/2410.24115

In the image:
Sketch of the projection of the side area of the detector (the ‘can’) onto the sea surface.

Astronomy potential of ARCA

22 November 2024 – In a paper with the title ‘Astronomy potential of KM3NeT/ARCA’ we present improvements that indeed enhance the astronomy potential of the ARCA detector.

An important scientific objective for constructing the ARCA detector is the detection of high-energy cosmic neutrinos from point-like sources. Scattering off the quarks inside a nucleon, neutrinos induce hadrons that generate a shower of particles. In so-called charge current interactions also a charged lepton is produced: a muon, electron or tau. These leptons have different signatures in the detector. Muons traverse the detector with a straight track of light, while electrons and taus generate outburst of light in the detector. $W^{\pm}$

With the ARCA detector, we can use both detection signatures for investigating the Southern Sky, where many neutrino sources are expected along the Galactic Plane. For this we further improved the neutrino event selection method and the event reconstruction software of both track-like and shower-like events.

Simulations show that the improvements enhanced the sensitivity and discovery potential of ARCA for neutrino sources by 5-15%.

The paper is published in EPJ-C:

Eur. Phys. J. C 84, 885 (2024)

DOI: 10.1140/epjc/s10052-024-13137-2)

In the image (click on the image for a better resolution):

The ARCA point-like source sensitivity (black curves) as a function of sin(δ) (δ is the declination angle) with γ = 2.0 (γ is spectral index, which matches the energy spectrum of cosmic rays undergoing Fermi acceleration) . For comparison, the results of 15 years of observation with the ANTARES telescope (green curve) and 7 and 10 years of of observation with the IceCube telescope (red curves) are also shown.

First searches for Dark Matter

20 November 2024 – In a new paper with the title ‘First searches for Dark Matter with the KM3NeT Neutrino Telescopes’ we present limits for neutrino production by Dark Matter annihilation in the Sun and the Galactic Centre. For the analysis we used the data of early configurations of the ARCA and ORCA detectors of KM3NeT.

We tested for different dark matter masses, spanning from a few GeV/c^2 up to 100 TeV/c^2, but did not find a dark matter signal in the data of ARCA from the direction of the Galactic Centre. Instead, we set a limit on the self-annihilation cross section of dark matter into five different Standard Model particles, for the different dark matter masses tested.

In the data of ORCA we did not find a dark matter signal from the Sun. In this case, we could set a limit on the cross section of the scattering process between dark matter and nucleons.

The paper is submitted to JCAP. A pre-print is stored at the arXiv: https://arxiv.org/abs/2411.10092

In the image:
90% CF upper limits on the thermally-averaged Weakly Interacting Massive Particles (WIMPs, candidate Dark Matter particles) annihilation cross section as a function of the WIMP mass for the τ⁺τ^–annihilation channel. The limit was obtained using data sets from the ARCA8, ARCA19 and ARCA21 configurations. For comparison, results obtained by other experiments are also shown.

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.

Quantum decoherence with ORCA6

30 October 2024 – Search for quantum decoherence in neutrino oscillations with six detection units of KM3NeT/ORCA

(KM3NeT paper, submitted to JCAP, arXiv: 2410.01388)

In a new paper we search for quantum decoherence in neutrino oscillations by looking for deviations of the standard neutrino oscillation pattern. We report upper limits on the decoherence parameters using data from ORCA6.

Usually, neutrino oscillations are studied in the framework of quantum mechanics assuming that the neutrino system is isolated. In this paper we study neutrino oscillations in the framework of open quantum systems, where the neutrino is coupled to a larger environment.

Several theories of quantum gravity postulate fluctuations in spacetime as a stochastic environment. A neutrino that propagates in such an environment will experience changes to its quantum phase. This will lead to a loss of coherence of the neutrino mass eigenstates during propagation. The phenomenon is referred to as decoherence in neutrino oscillations.

The search for decoherence in neutrino oscillations provides a rare opportunity to investigate quantum gravitational effects which are usually beyond the reach of current experiments.

The ORCA detector of KM3NeT is particularly designed to detect neutrinos generated in collision of cosmic ray particles with the Earth’s atmosphere. The atmospheric neutrinos are good probes to study oscillations and hence to search for quantum decoherence effects.

We used the neutrino data collected by the ORCA6 detector – an early detector configuration with six detection units – in the period January 2020 to November 2021. In the analysis we focused on atmospheric neutrinos with energies of a few GeV to 100 GeV. We measured the parameters Γ₂₁and Γ₃₁, that describe decoherence, assuming a power-law dependency on the neutrino energy Γ_ij ∝ (E/E₀)ⁿand explored two cases: with n = -2 and with n = -1.

Results

No significant deviation with respect to the standard oscillation hypothesis is observed. Therefore, 90% CL upper limits for the two cases are estimated as

The decoherence sensitivity of ORCA depends on the neutrino mass ordering. Therefore, we report upper limits for both normal and inverted ordering.

The results are comparable to bounds reported for IceCube/DeepCore and display the same dependency on the mass ordering.

In the figure below the 90% confidence level contours for Γ₂₁ and Γ₃₁ are shown for a decoherence model fitting both normal (NO) and inverted (IO) neutrino mass orderings.

Neutrino oscillations with ORCA6

29 October 2024 – Measurement of neutrino oscillation parameters with the first six detection units of KM3NeT/ORCA

(KM3NeT paper, accepted by JHEP, arXiv: 2408.07015)

In a new paper we show the potential of the ORCA detector: the measurements of neutrino oscillation parameters – with only 5% of ORCA’s final volume and during limited observation time – align with those from other experiments and are already becoming competitive.

Since the discovery of neutrino oscillations, the three-flavour neutrino model with non-zero neutrino masses has become well-established. The oscillation parameters are being measured with improving precision by several experiments world-wide. However, several questions persist. Among them the question what the value of the neutrino mixing angle θ₂₃ is and the question whether the ordering of the three neutrino masses is “normal” (NO) with m₁<m₂≪m₃ or “inverted” (IO) with m₃≪m₁<m₂. KM3NeT has joined the effort to answering these questions using its ORCA detector.

Neutrinos created in collisions of cosmic ray particles with the Earth’s atmosphere are good probes to study the neutrino oscillations. The ORCA detector in the Mediterranean Sea is particularly designed to detect atmospheric neutrinos. Therefore, it is an optimal detector for the measurement of neutrino oscillation parameters.

However, the ORCA detector is still under construction. The paper reports on the measurements with ORCA6 – an initial detector configuration that comprises six out of the foreseen 115 detection units. We extracted a high-purity neutrino sample, corresponding to an exposure of 433 kton-years. The sample of 5828 neutrino candidates was analysed following a binned log-likelihood method in the reconstructed neutrino energy and the cosine of the zenith angle.

Results

The atmospheric oscillation parameters measured with ORCA6 for both normal (NO) and inverted (IO) neutrino mass ordering are:

The inverted neutrino mass ordering hypothesis is disfavoured with a p-value of 0.25.

The 90% confidence level contours for the fitted oscillation parameters are shown in the left figure below with a solid line assuming normal ordering (NO) and a dashed line assuming inverted ordering (IO).

In the figure at the right you find a comparison of the contour – assuming NO – with the corresponding contours measured by other experiments. The ORCA contour aligns with those other measurements and, moreover, it shows that ORCA is becoming competitive.

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.

Search for neutrinos from GRB 221009A

13 August 2024 – Gamma-ray bursts are promising candidate sources of high-energy astrophysical neutrinos. The recent GRB 221009A event, identified as the brightest gamma-ray burst ever detected, provides a unique opportunity to investigate hadronic emissions involving neutrinos.

KM3NeT participated in the worldwide follow-up effort triggered by the GRB 221009A event, searching for neutrino events.

In a paper with the title ‘Search for neutrino emission from GRB 221009A using the KM3NeT ARCA and ORCA detectors’ we summarise subsequent searches in the energy range from MeV up to a few PeVs.

We did not find neutrino events, but set upper limits on the neutrino emission associated with GRB 221009A.

The paper is published in:

JCAP08(2024)006

DOI: 10.1088/1475-7516/2024/08/006

In the image:

90% CL upper limits on the neutrino flux from GRB 221009A for ARCA (blue) and ORCA (red). For comparison the results of IceCube are also shown (green) as well as the gamma-ray observations of Fermi-GBM, Fermi-LAT, and LHAASO (gray dashed lines).

KM3NeT - Recent News

Paul De Jong – Spokesperson:

Damien Dornic – Deputy Spokesperson:

Rosa Coniglione – Physics and Software Manager:

Antonio D’Amico – Technical Project Manager:

In a new paper we search for quantum decoherence in neutrino oscillations by looking for deviations of the standard neutrino oscillation pattern. We report upper limits on the decoherence parameters using data from ORCA6.

Results

Results

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