Showing 1–50 of 176 results for author: Bruno, R

An Information Theoretic Treatment of Yager's Probability Distribution Negation

Authors: Roberto Bruno, Ugo Vaccaro

Abstract: In the seminal paper (Yager 2015), Yager defined the negation of a probability distribution $\mathbf{p}=(p_1,\dots,p_n)$, as the distribution $\overline{\mathbf{p}} = (\overline{p}_1,\dots,\overline{p}_n)$, where $\overline{p}_i = ({1-p_i})/({n-1}),$ for $ i=1, \ldots , n.$ In this paper, we present a comprehensive information-theoretic analysis of Yager's negation and its generalizations. Using t… ▽ More In the seminal paper (Yager 2015), Yager defined the negation of a probability distribution $\mathbf{p}=(p_1,\dots,p_n)$, as the distribution $\overline{\mathbf{p}} = (\overline{p}_1,\dots,\overline{p}_n)$, where $\overline{p}_i = ({1-p_i})/({n-1}),$ for $ i=1, \ldots , n.$ In this paper, we present a comprehensive information-theoretic analysis of Yager's negation and its generalizations. Using tools from information theory and majorization theory, we unify, extend, and strengthen a number of previously known properties of Yager's negation within a common framework. Overall, our results offer strong theoretical justification for Yager's negation as the most natural and principled definition of probability distribution negation under various information theoretic criteria. △ Less

Submitted 1 August, 2026; originally announced August 2026.

Comments: Published in Soft Computing (Section: Foundation, Algebraic, and Analytical Methods)

Journal ref: Soft Computing, 2026

Final assessment of radioactive impurities in the JUNO detector

Authors: Thomas Adam, Fengpeng An, Costas Andreopoulos, Giuseppe Andronico, Nikolay Anfimov, Vito Antonelli, Tatiana Antoshkina, João Pedro Athayde Marcondes de André, Didier Auguste, Nikita Balashov, Andrea Barresi, Davide Basilico, Eric Baussan, Marco Beretta, Antonio Bergnoli, Nikita Bessonov, Daniel Bick, Lukas Bieger, Svetlana Biktemerova, Thilo Birkenfeld, Simon Blyth, Manuel Böhles, Anastasia Bolshakova, Mathieu Bongrand, Matteo Borghesi , et al. (549 additional authors not shown)

Abstract: The Jiangmen Underground Neutrino Observatory (JUNO) collaboration has completed the construction of the 20,000-ton liquid scintillator detector and the associated muon veto detector system. To meet the physics objectives, the materials used in the detector must exhibit low radioactive contamination. The single-event rate in the fiducial volume (R $<$ 17.2 m) of the scintillator is required to be… ▽ More The Jiangmen Underground Neutrino Observatory (JUNO) collaboration has completed the construction of the 20,000-ton liquid scintillator detector and the associated muon veto detector system. To meet the physics objectives, the materials used in the detector must exhibit low radioactive contamination. The single-event rate in the fiducial volume (R $<$ 17.2 m) of the scintillator is required to be approximately 7 Hz for energies above 0.7 MeV, resulting in an accidental coincidence background of about 1 event per day for reactor neutrino physics analyses. Since the beginning of the construction phase, we have screened the natural radioactivity content of thousands of materials, to select those that meet the design background budget. The radioactive impurity concentrations of the materials ultimately used in the JUNO detector are summarized in this paper. The construction of the entire detector and the subsequent filling of the liquid scintillator were completed in August 2025. From the initial data, the total count rate of natural radioactivity within the detector's fiducial volume has met the requirements and is sufficient to support the reactor antineutrino analysis. △ Less

Submitted 19 July, 2026; originally announced July 2026.

A Low-energy Threshold and Multi-messenger Trigger System for the JUNO Experiment

Authors: Thomas Adam, Fengpeng An, Costas Andreopoulos, Giuseppe Andronico, Nikolay Anfimov, Vito Antonelli, Tatiana Antoshkina, João Pedro Athayde Marcondes de André, Didier Auguste, Nikita Balashov, Andrea Barresi, Davide Basilico, Eric Baussan, Marco Beretta, Antonio Bergnoli, Nikita Bessonov, Daniel Bick, Lukas Bieger, Svetlana Biktemerova, Thilo Birkenfeld, Simon Blyth, Manuel Boehles, Anastasia Bolshakova, Mathieu Bongrand, Matteo Borghesi , et al. (543 additional authors not shown)

Abstract: The Jiangmen Underground Neutrino Observatory (JUNO) is a 20-kiloton liquid scintillator neutrino detector, located 650 meters (1800 m.w.e.) underground in Jiangmen, Guangdong, China. JUNO is primarily designed for reactor neutrino measurements and has been taking data since 2025. With the largest mass of its kind and an excellent energy resolution, JUNO is a leading observatory for high-precision… ▽ More The Jiangmen Underground Neutrino Observatory (JUNO) is a 20-kiloton liquid scintillator neutrino detector, located 650 meters (1800 m.w.e.) underground in Jiangmen, Guangdong, China. JUNO is primarily designed for reactor neutrino measurements and has been taking data since 2025. With the largest mass of its kind and an excellent energy resolution, JUNO is a leading observatory for high-precision measurements of MeV neutrinos. The standard global trigger system serves as the primary trigger for JUNO. We present a newly developed multi-messenger trigger system that extends the capabilities of the global trigger by providing a lower energy threshold and an independent monitoring capability. During the 2025 operation, it achieved an effective energy threshold of approximately 110 +/- 10 keV, providing a lower threshold configuration suitable for low-energy event analysis. The system shows the potential to further reduce the threshold to well below 100 keV. Based on the multi-messenger trigger system, an astrophysical monitor has been developed to receive and process external alerts from other messengers, such as gravitational-wave observations. A Transient Neutrino Burst Monitor is integrated to detect short-time-scale neutrino burst events and enables real-time monitoring of transient astrophysical phenomena. The system is sensitive to neutrino bursts from core-collapse supernovae within a distance of about 250 kpc. △ Less

Submitted 15 July, 2026; originally announced July 2026.

Comments: 29 pages, 19 figures, 3 tables

Ultra-trace analysis of 40K in organic liquid scintillators

Authors: A. Barresi, D. Chiesa, D. Merli, M. Nastasi, S. Nisi, E. Previtali, M. Sisti, M. Borghesi, A. Cammi, C. Coletta, G. Ferrante, L. Loi, G. Andronico, V. Antonelli, D. Basilico, M. Beretta, A. Bergnoli, A. Brigatti, R. Brugnera, R. Bruno, A. Budano, B. Caccianiga, A. Caslini, V. Cerrone, R. Caruso , et al. (42 additional authors not shown)

Abstract: Rare-event searches require exceptionally low background levels, motivating the development of increasingly sophisticated screening methods to push sensitivity limits. Liquid scintillators are particularly attractive detector media due to their intrinsic radiopurity and the ability to scale to large target masses. In this work, we present a screening strategy capable of measuring ultra-trace conce… ▽ More Rare-event searches require exceptionally low background levels, motivating the development of increasingly sophisticated screening methods to push sensitivity limits. Liquid scintillators are particularly attractive detector media due to their intrinsic radiopurity and the ability to scale to large target masses. In this work, we present a screening strategy capable of measuring ultra-trace concentrations of $^{40}\text{K}$ with sensitivities below $10^{-15}$g/g. The method combines neutron activation analysis with a dedicated radiochemical treatment, followed by low-background HPGe gamma spectroscopy. Using this approach, we achieved a minimum detectable concentration of $2.9\cdot10^{-16}$g/g for $^{40}\text{K}$, placing this technique among the most sensitive currently available. △ Less

Submitted 8 July, 2026; originally announced July 2026.

Testing Heavy Dark Matter Decay as the Origin of KM3-230213A

Authors: KM3NeT Collaboration, O. Adriani, J. A. Aguilar, A. Albert, A. R. Alhebsi, S. Alshalloudi, F. Ameli, M. Andre, L. Aphecetche, M. Ardid, S. Ardid, J. Aublin, F. Badaracco, B. Baret, A. Bariego-Quintana, L. Barigione, M. Barnard, Y. Becherini, M. Bendahman, F. Benfenati Gualandi, M. Benhassi, D. M. Benoit, Z. Beňušová, E. Berbee, C. van Bergen , et al. (265 additional authors not shown)

Abstract: This work explores the hypothesis that the ultra-high-energy neutrino event KM3-230213A originates from the decay of a heavy dark matter particle with a mass above PeV scale. The analysis exploits the deposited energy and arrival direction of the event as well as a complete detector Monte Carlo simulation to compute the expected signal distributions for different decay channels and assesses the re… ▽ More This work explores the hypothesis that the ultra-high-energy neutrino event KM3-230213A originates from the decay of a heavy dark matter particle with a mass above PeV scale. The analysis exploits the deposited energy and arrival direction of the event as well as a complete detector Monte Carlo simulation to compute the expected signal distributions for different decay channels and assesses the relative contributions from Galactic and extragalactic dark matter. Assuming a dark matter origin of the event, we find that the preferred mass at 95% C.L. is larger than about 100 PeV in all scenarios considered, with best-fit lifetimes in the range $10^{26}$-$10^{27}$ s. These preferred regions are in tension with existing bounds from other neutrino telescopes and gamma-ray observations. △ Less

Submitted 8 June, 2026; originally announced June 2026.

Comments: 11 pages, 3 figures, 1 table

Probing Solar Wind Structures with Solar Energetic Particle Observations from Solar Orbiter

Authors: Xiaohang Chen, Gang Li, Joe Giacalone, Xiangliang Kong, Shuai Fu, Rumeng Zhang, Changyue Zhao, George C. Ho, David Lario, Zheyi Ding, Robert F. Wimmer-Schweingruber, Glenn M. Mason, Roberto Bruno, Nicolas Wijsen, Javier Rodríguez-Pacheco

Abstract: The propagation of solar energetic particles (SEPs) through the heliosphere is primarily guided by the interplanetary magnetic field (IMF) which is embedded in the solar wind plasma. Large-scale IMF structures can drive transient variations in SEP intensities. Using Solar Orbiter observations, we identify a distinct class of SEP variations: SEP flux deflections (SFDs), which are commonly detected… ▽ More The propagation of solar energetic particles (SEPs) through the heliosphere is primarily guided by the interplanetary magnetic field (IMF) which is embedded in the solar wind plasma. Large-scale IMF structures can drive transient variations in SEP intensities. Using Solar Orbiter observations, we identify a distinct class of SEP variations: SEP flux deflections (SFDs), which are commonly detected in SEP events and frequently recur multiple times within a single event. SFDs are characterized by a sudden change in SEP flux directions where the intensities drop in one direction and increase in another direction, without a significant net change in total flux magnitude. These deflections occur dispersionlessly across a broad energy range-from tens of keV to over 100 MeV-and exhibit steep intensity gradients. SFDs are typically associated with magnetic flux tubes with boundary features consistent with tangential discontinuities. We further show that the solar wind inside these structures exhibits distinct plasma properties, and that the SEP streaming direction within SFDs aligns closely to the flux-tube axis. These observations suggest that magnetic flux tubes are a prevalent structural element of the solar wind, and demonstrate that SEPs can serve as an effective diagnostic tool for probing the topology and dynamics of solar wind structures. △ Less

Submitted 22 May, 2026; originally announced May 2026.

The Sharma-Mittal Entropy is Subadditive and Supermodular on the Majorization Lattice

Authors: Roberto Bruno, Ugo Vaccaro

Abstract: We prove that Sharma-Mittal entropy is a subadditive and supermodular function on the lattice of all $n$-dimensional probability distributions, ordered according to the partial order relation defined by majorization among vectors. Our result unifies and extends analogous results presented in the literature for the Shannon entropy, the Tsallis entropy, and the Rényi entropy. We prove that Sharma-Mittal entropy is a subadditive and supermodular function on the lattice of all $n$-dimensional probability distributions, ordered according to the partial order relation defined by majorization among vectors. Our result unifies and extends analogous results presented in the literature for the Shannon entropy, the Tsallis entropy, and the Rényi entropy. △ Less

Submitted 26 May, 2026; v1 submitted 18 May, 2026; originally announced May 2026.

Comments: Preliminary version

Full band denoising of room impulse response in the wavelet domain with dictionary learning

Authors: Théophile Dupré, Romain Couderc, Miguel Moleron, Axel Coulon, Rémy Bruno, Arnaud Laborie

Abstract: Conventional wavelet-domain methods for room impulse response denoising rely on thresholding detail coefficients, which is unsuited for low frequencies. In this work, we introduce a wavelet-based post-processing algorithm that extends denoising to approximation coefficients by means of sparse dictionary learning with a time-varying error tolerance. The proposed method leverages an exponential deca… ▽ More Conventional wavelet-domain methods for room impulse response denoising rely on thresholding detail coefficients, which is unsuited for low frequencies. In this work, we introduce a wavelet-based post-processing algorithm that extends denoising to approximation coefficients by means of sparse dictionary learning with a time-varying error tolerance. The proposed method leverages an exponential decay envelope model to adapt reconstruction accuracy according to the local signal-to-noise ratio. This approach significantly improves low-frequency denoising of synthetic and measured room impulse responses compared to the baseline method, leading to more accurate estimation of acoustic parameters such as decay time. △ Less

Submitted 29 April, 2026; originally announced April 2026.

Embedded underwater front-end electronics for the 3-inch photomultipliers in the JUNO experiment

Authors: Cédric Cerna, Miao He, Xiaoshan Jiang, Juan Pedro Ochoa-Ricoux, Frédéric Perrot, Angel Abusleme, Thomas Adam, Fengpeng An, Costas Andreopoulos, Giuseppe Andronico, João Pedro Athayde Marcondes de André, Nikolay Anfimov, Vito Antonelli, Tatiana Antoshkina, Didier Auguste, Nikita Balashov, Andrea Barresi, Davide Basilico, Eric Baussan, Marco Beretta, Antonio Bergnoli, Nikita Bessonov, Daniel Bick, Lukas Bieger, Svetlana Biktemerova , et al. (576 additional authors not shown)

Abstract: The Jiangmen Underground Neutrino Observatory (JUNO) is a 20-kton liquid scintillator-based, low-radioactivity, multi-purpose neutrino detector located 693 meters (1800 m.w.e.) underground in the Guangdong province, China. To detect scintillation light produced in the target, the detector is equipped with 17,612 20-inch photomultipliers (PMTs), forming the Large PMT system (LPMT). In addition, 25,… ▽ More The Jiangmen Underground Neutrino Observatory (JUNO) is a 20-kton liquid scintillator-based, low-radioactivity, multi-purpose neutrino detector located 693 meters (1800 m.w.e.) underground in the Guangdong province, China. To detect scintillation light produced in the target, the detector is equipped with 17,612 20-inch photomultipliers (PMTs), forming the Large PMT system (LPMT). In addition, 25,600 3-inch photomultipliers (the Small Photomultiplier System or SPMT) are deployed in the gaps between the LPMTs. This paper presents the design and performance of the underwater front-end electronics developed for the SPMT system. It details the individual electronics boards and their key components, the inter-board interfaces, the system-level design, and the firmware architecture that supports data acquisition and control. It also outlines mechanical and thermal integration, board validation procedures, and system performance metrics. The readout chain includes digitization of 128 PMT channels per unit, synchronized time-stamping, charge measurement, event packaging, and bandwidth management. Comprehensive validation confirms the system's readiness to meet JUNO's stringent physics goals. The underwater electronics achieve noise levels as low as 0.04 photoelectrons with minimal crosstalk (below 0.4%) and a bandwidth of 57 MB/s, ensuring reliable single photo-electron detection and operation under high-rate conditions. The SPMT system has now been fully integrated and installed in JUNO. Its commissioning and physics performance will be reported in a future publication. △ Less

Submitted 1 June, 2026; v1 submitted 28 April, 2026; originally announced April 2026.

Comments: Submitted to Nucl. Instrum. Methods Phys. Res. A

Real-Time Wiener Deconvolution for feature reconstruction in JUNO

Authors: L. Lastrucci, M. Grassi, A. Triossi, J. Hu, X. Jiang, R. Brugnera, A. Garfagnini, V. Cerrone, L. V. D'Auria, A. Gavrikov, R. M. Guizzetti, A. Serafini, G. Andronico, V. Antonelli, A. Barresi, D. Basilico, M. Beretta, A. Bergnoli, M. Borghesi, A. Brigatti, R. Bruno, A. Budano, B. Caccianiga, A. Cammi, R. Caruso , et al. (52 additional authors not shown)

Abstract: In particle physics, experiments generate substantial amounts of data that can be difficult to process without preliminary scaling. To avoid losing potentially crucial data, experimental collaborations are studying novel techniques for real-time data processing to extract features for further physics analysis. A common approach, especially in neutrino physics, is to use FPGAs for data acquisition… ▽ More In particle physics, experiments generate substantial amounts of data that can be difficult to process without preliminary scaling. To avoid losing potentially crucial data, experimental collaborations are studying novel techniques for real-time data processing to extract features for further physics analysis. A common approach, especially in neutrino physics, is to use FPGAs for data acquisition and pre-processing. This paper presents an advanced Real-Time Wiener deconvolution algorithm designed to leverage the processing capabilities of the FPGA integrated into the readout boards of the Jiangmen Underground Neutrino Observatory (JUNO). The goal is to enable real-time reconstruction of the signal generated by photomultiplier tubes (PMTs) when neutrino interactions are detected. By exploiting online reconstruction of the signal generated by PMTs, we expect to improve the detection of low-energy depositions, such as those produced by transient astrophysical phenomena. These depositions are usually not saved because of the significant background that affects the low end of the energy spectrum, which would result in a large trigger rate, hence a large amount of data required for storage. This paper presents the features of the algorithm, including its ability to manage high-throughput data streams with minimal latency, adaptability, and resilience in discerning the characteristics of input data. Performance is evaluated on a JUNO electronic board. This study further demonstrates the potential of FPGA-based solutions for neutrino physics. △ Less

Submitted 26 March, 2026; originally announced March 2026.

Atmospheric neutrino constraints on Lorentz invariance violation with the first six detection units of KM3NeT/ORCA

Authors: KM3NeT Collaboration, O. Adriani, A. Albert, A. R. Alhebsi, S. Alshalloudi, S. Alves Garre, F. Ameli, M. Andre, L. Aphecetche, M. Ardid, S. Ardid, J. Aublin, F. Badaracco, L. Bailly-Salins, B. Baret, A. Bariego-Quintana, L. Barigione, M. Barnard, Y. Becherini, M. Bendahman, F. Benfenati Gualandi, M. Benhassi, D. M. Benoit, Z. Beňušová, E. Berbee , et al. (272 additional authors not shown)

Abstract: Lorentz invariance is a fundamental symmetry underlying both the Standard Model of particle physics and General Relativity. Testing its validity provides a direct means of searching for new physics emerging near the Planck scale. A search for isotropic Lorentz invariance violation with 1.4 years of atmospheric neutrino data collected by a partial configuration of the KM3NeT/ORCA detector comprisin… ▽ More Lorentz invariance is a fundamental symmetry underlying both the Standard Model of particle physics and General Relativity. Testing its validity provides a direct means of searching for new physics emerging near the Planck scale. A search for isotropic Lorentz invariance violation with 1.4 years of atmospheric neutrino data collected by a partial configuration of the KM3NeT/ORCA detector comprising six detection units is presented. No evidence for such violation is found; thus, competitive limits are set on a subset of isotropic Lorentz invariance violating coefficients, which complement and extend existing experimental constraints. △ Less

Submitted 4 March, 2026; originally announced March 2026.

Mechanistic Learning for Survival Prediction in NSCLC Using Routine Blood Biomarkers and Tumor Kinetics

Authors: Ruben Taieb, René Bruno, Pascal Chanu, Jin Yan Jin, Sébastien Benzekry

Abstract: Background Predicting overall survival (OS) in non-small cell lung cancer (NSCLC) is essential for clinical decision-making and drug development. While tumor and blood test markers kinetics are intrinsically linked, their joint dynamics and relationship to OS remain unknown. Methods We developed a mechanistic model capturing the interplay between tumor (T) burden and three key blood markers kineti… ▽ More Background Predicting overall survival (OS) in non-small cell lung cancer (NSCLC) is essential for clinical decision-making and drug development. While tumor and blood test markers kinetics are intrinsically linked, their joint dynamics and relationship to OS remain unknown. Methods We developed a mechanistic model capturing the interplay between tumor (T) burden and three key blood markers kinetics: albumin (A), lactate dehydrogenase (L), and neutrophils (N), through coupled differential equations (termed TALN-k). This model was enhanced with a machine learning framework (TALN-kML) for OS prediction. The model was trained and validated on clinical trial data from NSCLC patients treated with atezolizumab in monotherapy (N = 862 patients) or combination therapy (N = 1,115). Model parameters were estimated using nonlinear mixed-effects modelling, and survival predictions were assessed using individual and trial level metrics. Results TALN-k successfully described individual and population-level marker kinetics, revealing complex interactions between tumor and blood markers, and improving corrected BIC and log-likelihood metrics by a significant margin of previous empirical state-of-the-art models. Feature selection methods also highlighted valuable predictive parameters, indicatives of good or poor prognosis. The TALN-kML model outperformed empirical, uncoupled models, achieving improved C-index (0.74 $\pm$ 0.02 vs 0.72 $\pm$ 0.03), 12-months AUC (0.83 $\pm$ 0.004 vs 0.79 $\pm$ 0.05), and accuracy (0.77 $\pm$ 0.03 vs 0.76 $\pm$ 0.05) in OS prediction. Conclusion Our mechanistic learning approach allows for an interpretable model, which improves on longitudinal data description and on survival prediction in NSCLC by jointly integrating tumor and blood markers kinetics. This methodology offers a promising avenue for both personalized treatment strategies and drug development optimization. △ Less

Submitted 16 January, 2026; originally announced January 2026.

A Finite-Sample Strong Converse for Binary Hypothesis Testing via (Reverse) Rényi Divergence

Authors: Roberto Bruno, Adrien Vandenbroucque, Amedeo Roberto Esposito

Abstract: This work investigates binary hypothesis testing between $H_0\sim P_0$ and $H_1\sim P_1$ in the finite-sample regime under asymmetric error constraints. By employing the ``reverse" Rényi divergence, we derive novel non-asymptotic bounds on the Type II error probability which naturally establish a strong converse result. Furthermore, when the Type I error is constrained to decay exponentially with… ▽ More This work investigates binary hypothesis testing between $H_0\sim P_0$ and $H_1\sim P_1$ in the finite-sample regime under asymmetric error constraints. By employing the ``reverse" Rényi divergence, we derive novel non-asymptotic bounds on the Type II error probability which naturally establish a strong converse result. Furthermore, when the Type I error is constrained to decay exponentially with a rate $c$, we show that the Type II error converges to 1 exponentially fast if $c$ exceeds the Kullback-Leibler divergence $D(P_1\|P_0)$, and vanishes exponentially fast if $c$ is smaller. Finally, we present numerical examples demonstrating that the proposed converse bounds strictly improve upon existing finite-sample results in the literature. △ Less

Submitted 17 January, 2026; v1 submitted 14 January, 2026; originally announced January 2026.

Comments: An extended version, with proofs, of a paper submitted to ISIT 2026

Alfvénic solar wind intervals observed by Solar Orbiter: Exploiting the capability of the SWA plasma suite and source region investigation

Authors: R. D'Amicis, J. M. Raines, S. Benella, M. Velli, O. Panasenco, G. Nicolaou, C. J. Owen, R. M. Dewey, P. Louarn, A. Fedorov, S. T. Lepri, B. L. Alterman, D. Perrone, R. De Marco, R. Bruno, L. Sorriso-Valvo, O. S. Dhamane, Y. Rivera, O. R. Kieokaew, D. Verscharen, G. Consolini, S. Yardley, V. Réville, D. Telloni, D. Baker , et al. (10 additional authors not shown)

Abstract: Fast and slow solar wind have distinct properties linked to their solar sources.Alfvénic slow wind complicates the usual speed-based classification, especially at intermediate speeds. Solar Orbiter's Solar Wind Analyzer (SWA) offers unique capabilities to investigate how Alfvénic slow wind differs from fast wind and relate these differences to their solar origins. In September 2022, Solar Orbiter… ▽ More Fast and slow solar wind have distinct properties linked to their solar sources.Alfvénic slow wind complicates the usual speed-based classification, especially at intermediate speeds. Solar Orbiter's Solar Wind Analyzer (SWA) offers unique capabilities to investigate how Alfvénic slow wind differs from fast wind and relate these differences to their solar origins. In September 2022, Solar Orbiter observed several Alfvénic streams: one fast wind, three Alfvénic slow wind (AS1, AS2, AS3), and a moderate fast (FH) interval. We analyze these streams, combining plasma parameters from all SWA sensors with magnetic field measurements from the Magnetometer (MAG). A spectral analysis of magnetic and velocity fluctuations is used to characterize Alfvénicity. The magnetic connectivity of each stream to its solar source is examined using Potential Field Source Surface extrapolation combined with ballistic backmapping from the spacecraft. Proton velocity distribution functions show anisotropies and field-aligned beams characteristic of Alfvénic streams, while electron pitch-angle distributions reveal clear strahl populations. Oxygen and carbon charge-state ratios are low in fast wind but higher in AS1-AS3, consistent with slow wind origins. Magnetic connectivity suggests the fast wind originates from a large coronal hole; AS1 links to a pseudostreamer with high expansion factor; AS2, AS3, and FH connect to a negative-polarity coronal hole whose field lines cross a pseudostreamer that later dissipates. Spectral analysis indicates near energy equipartition in all intervals except AS2. The combined SWA observations offer key insights into the physical processes shaping Alfvénic solar wind streams. Our results reinforce that the simple fast/slow wind classification is inadequate for linking solar wind to sources, and suggest that Alfvénicity relates to the solar source conditions. △ Less

Submitted 23 December, 2025; originally announced December 2025.

Ultra-trace analysis of U and Th in organic liquid scintillators with high sensitivity

Authors: A. Barresi, D. Chiesa, D. Merli, M. Nastasi, S. Nisi, E. Previtali, M. Sisti, M. Borghesi, A. Cammi, C. Coletta, G. Ferrante, L. Loi, G. Andronico, V. Antonelli, D. Basilico, M. Beretta, A. Bergnoli, A. Brigatti, R. Brugnera, R. Bruno, A. Budano, B. Caccianiga, V. Cerrone, R. Caruso, C. Clementi , et al. (41 additional authors not shown)

Abstract: Rare event searches demand extremely low background levels, necessitating ever-advancing screening techniques to enhance sensitivity. Liquid scintillators are highly attractive as detector media due to their inherent radiopurity and scalability in mass. In this work, we present a screening procedure to measure ultra-trace concentrations of natural contaminants -- $^{238}$U and $^{232}$Th -- with s… ▽ More Rare event searches demand extremely low background levels, necessitating ever-advancing screening techniques to enhance sensitivity. Liquid scintillators are highly attractive as detector media due to their inherent radiopurity and scalability in mass. In this work, we present a screening procedure to measure ultra-trace concentrations of natural contaminants -- $^{238}$U and $^{232}$Th -- with sensitivities at the \qty{E-15}{g/g} level. Our method combines neutron activation analysis with radiochemical techniques, followed by \bg\ coincidence spectroscopy to minimize interference backgrounds. This approach achieves sensitivities of \qty{0.65E-15}{g/g} for $^{238}$U and \qty{2.3E-15}{g/g} for $^{232}$Th, among the best reported worldwide. Potential pathways for further sensitivity improvements are outlined in the conclusions. △ Less

Submitted 6 December, 2025; originally announced December 2025.

Optimizing the potential of KM3NeT in detecting core-collapse supernovae

Authors: KM3NeT Collaboration, O. Adriani, A. Albert, A. R. Alhebsi, S. Alshalloudi, M. Alshamsi, S. Alves Garre, F. Ameli, M. Andre, L. Aphecetche, M. Ardid, S. Ardid, J. Aublin, F. Badaracco, L. Bailly-Salins, B. Baret, A. Bariego-Quintana, Y. Becherini, M. Bendahman, F. Benfenati Gualandi, M. Benhassi, D. M. Benoit, Z. Beňušová, E. Berbee, E. Berti , et al. (263 additional authors not shown)

Abstract: Core-collapse supernovae mark the end of life of massive stars. However, despite their importance in astrophysics, their underlying mechanisms remain unclear. Neutrinos that emerge from the dense core of the star offer a promising way to study supernova dynamics. A strategy is presented to improve the potential of the KM3NeT neutrino telescope to detect core-collapse supernovae in our Galaxy or th… ▽ More Core-collapse supernovae mark the end of life of massive stars. However, despite their importance in astrophysics, their underlying mechanisms remain unclear. Neutrinos that emerge from the dense core of the star offer a promising way to study supernova dynamics. A strategy is presented to improve the potential of the KM3NeT neutrino telescope to detect core-collapse supernovae in our Galaxy or the Large Magellanic Cloud by further exploiting the properties of its optical modules equipped with multiple photomultipliers. A supernova burst is expected to produce a sudden hit rate increase in the KM3NeT detectors. New observables have been defined for individual optical modules that exploit the geometry and time distribution of the detected hits, enabling a better discrimination between signal and background signatures. In addition, a thorough investigation of the related systematic uncertainties is presented for the first time. When implemented, this new methodology allowed KM3NeT to probe 46% more Galactic core-collapse supernova candidates than with the previous trigger strategy, reaching the dense Galactic bulge. It is now expected that, once completed, KM3NeT will achieve full Galactic sensitivity to core-collapse supernovae. △ Less

Submitted 13 January, 2026; v1 submitted 23 November, 2025; originally announced November 2025.

Comments: 24 pages, 11 figures

First measurement of reactor neutrino oscillations at JUNO

Authors: Angel Abusleme, Thomas Adam, Kai Adamowicz, David Adey, Shakeel Ahmad, Rizwan Ahmed, Timo Ahola, Sebastiano Aiello, Fengpeng An, Guangpeng An, Costas Andreopoulos, Giuseppe Andronico, João Pedro Athayde Marcondes de André, Nikolay Anfimov, Vito Antonelli, Tatiana Antoshkina, Burin Asavapibhop, Didier Auguste, Margherita Buizza Avanzini, Andrej Babic, Jingzhi Bai, Weidong Bai, Nikita Balashov, Roberto Barbera, Andrea Barresi , et al. (1114 additional authors not shown)

Abstract: Neutrino oscillations, a quantum effect manifesting at macroscopic scales, are governed by lepton flavor mixing angles and neutrino mass-squared differences that are fundamental parameters of particle physics, representing phenomena beyond the Standard Model. Precision measurements of these parameters are essential for testing the completeness of the three-flavor framework, determining the mass or… ▽ More Neutrino oscillations, a quantum effect manifesting at macroscopic scales, are governed by lepton flavor mixing angles and neutrino mass-squared differences that are fundamental parameters of particle physics, representing phenomena beyond the Standard Model. Precision measurements of these parameters are essential for testing the completeness of the three-flavor framework, determining the mass ordering of neutrinos, and probing possible new physics. The Jiangmen Underground Neutrino Observatory (JUNO) is a 20 kton liquid-scintillator detector located 52.5 km from multiple reactor cores, designed to resolve the interference pattern of reactor neutrinos with sub-percent precision. Here we report, using the first 59.1 days of data collected since detector completion in August 2025, the first simultaneous high-precision determination of two neutrino oscillation parameters, $\sin^2 θ_{12} = 0.3092\,\pm\,0.0087$ and $Δm^2_{21} = (7.50\,\pm\,0.12)\times10^{-5}\;{\rm eV}^2$ for the normal mass ordering scenario, improving the precision by a factor of 1.6 relative to the combination of all previous measurements. These results advance the basic understanding of neutrinos, validate the detector's design, and confirm JUNO's readiness for its primary goal of resolving the neutrino mass ordering with a larger dataset. The rapid achievement with a short exposure highlights JUNO's potential to push the frontiers of precision neutrino physics and paves the way for its broad scientific program. △ Less

Submitted 18 November, 2025; originally announced November 2025.

Comments: 30 pages, 11 figures

Initial performance results of the JUNO detector

Authors: Angel Abusleme, Thomas Adam, Kai Adamowicz, David Adey, Shakeel Ahmad, Rizwan Ahmed, Timo Ahola, Sebastiano Aiello, Fengpeng An, Guangpeng An, Costas Andreopoulos, Giuseppe Andronico, João Pedro Athayde Marcondes de André, Nikolay Anfimov, Vito Antonelli, Tatiana Antoshkina, Burin Asavapibhop, Didier Auguste, Margherita Buizza Avanzini, Andrej Babic, Jingzhi Bai, Weidong Bai, Nikita Balashov, Roberto Barbera, Andrea Barresi , et al. (1114 additional authors not shown)

Abstract: The Jiangmen Underground Neutrino Observatory (JUNO) started physics data taking on 26 August 2025. JUNO consists of a 20-kton liquid scintillator central detector, surrounded by a 35 kton water pool serving as a Cherenkov veto, and almost 1000 m$^2$ of plastic scintillator veto on top. The detector is located in a shallow underground laboratory with an overburden of 1800 m.w.e. This paper present… ▽ More The Jiangmen Underground Neutrino Observatory (JUNO) started physics data taking on 26 August 2025. JUNO consists of a 20-kton liquid scintillator central detector, surrounded by a 35 kton water pool serving as a Cherenkov veto, and almost 1000 m$^2$ of plastic scintillator veto on top. The detector is located in a shallow underground laboratory with an overburden of 1800 m.w.e. This paper presents the performance results of the detector, extensively studied during the commissioning of the water phase, the subsequent liquid scintillator filling phase, and the first physics runs. The liquid scintillator achieved an attenuation length of 20.6 m at 430 nm, while the high coverage PMT system and scintillator together yielded about 1785 photoelectrons per MeV of energy deposit at the detector centre, measured using the 2.223 MeV $γ$ from neutron captures on hydrogen with an Am-C calibration source. The reconstructed energy resolution is 3.4% for two 0.511 MeV $γ$ at the detector centre and 2.9% for the 0.93 MeV quenched Po-214 alpha decays from natural radioactive sources. The energy nonlinearity is calibrated to better than 1%. Intrinsic contaminations of U-238 and Th-232 in the liquid scintillator are below 10$^{-16}$ g/g, assuming secular equilibrium. The water Cherenkov detector achieves a muon detection efficiency better than 99.9% for muons traversing the liquid scintillator volume. During the initial science runs, the data acquisition duty cycle exceeded 97.8%, demonstrating the excellent stability and readiness of JUNO for high-precision neutrino physics. △ Less

Submitted 18 November, 2025; originally announced November 2025.

Comments: 38 pages, 23 figures

Prospects for geoneutrino detection with JUNO

Authors: Thomas Adam, Shakeel Ahmad, Rizwan Ahmed, Fengpeng An, João Pedro Athayde Marcondes de André, Costas Andreopoulos, Giuseppe Andronico, Nikolay Anfimov, Vito Antonelli, Tatiana Antoshkina, Didier Auguste, Marcel Büchner, Weidong Bai, Nikita Balashov, Andrea Barresi, Davide Basilico, Eric Baussan, Marco Beretta, Antonio Bergnoli, Nikita Bessonov, Daniel Bick, Lukas Bieger, Svetlana Biktemerova, Thilo Birkenfeld, Simon Blyth , et al. (605 additional authors not shown)

Abstract: Geoneutrinos, which are antineutrinos emitted during the decay of long-lived radioactive elements inside Earth, serve as a unique tool for studying the composition and heat budget of our planet. The Jiangmen Underground Neutrino Observatory (JUNO) experiment in China, which has recently completed construction, is expected to collect a sample comparable in size to the entire existing world geoneutr… ▽ More Geoneutrinos, which are antineutrinos emitted during the decay of long-lived radioactive elements inside Earth, serve as a unique tool for studying the composition and heat budget of our planet. The Jiangmen Underground Neutrino Observatory (JUNO) experiment in China, which has recently completed construction, is expected to collect a sample comparable in size to the entire existing world geoneutrino dataset in less than a year. This paper presents an updated estimation of sensitivity to geoneutrinos of JUNO using the best knowledge available to date about the experimental site, the surrounding nuclear reactors, the detector response uncertainties, and the constraints expected from the TAO satellite detector. To facilitate comparison with present and future geological models, our results cover a wide range of predicted signal strengths. Despite the significant background from reactor antineutrinos, the experiment will measure the total geoneutrino flux with a precision comparable to that of existing experiments within its first few years, ultimately achieving a world-leading precision of about 8% over ten years. The large statistics of JUNO will also allow separation of the Uranium-238 and Thorium-232 contributions with unprecedented precision, providing crucial constraints on models of formation and composition of Earth. Observation of the mantle signal above the lithospheric flux will be possible but challenging. For models with the highest predicted mantle concentrations of heat-producing elements, a 3-sigma detection over six years requires knowledge of the lithospheric flux to within 15%. Together with complementary measurements from other locations, the geoneutrino results of JUNO will offer cutting-edge, high-precision insights into the interior of Earth, of fundamental importance to both the geoscience and neutrino physics communities. △ Less

Submitted 10 November, 2025; originally announced November 2025.

Comments: 32 pages, with 13 figures and 5 tables

Search for an eV-scale sterile neutrino with the first six detection units of KM3NeT/ORCA

Authors: KM3NeT Collaboration, O. Adriani, A. Albert, A. R. Alhebsi, S. Alshalloudi, M. Alshamsi, S. Alves Garre, F. Ameli, M. Andre, L. Aphecetche, M. Ardid, S. Ardid, J. Aublin, F. Badaracco, L. Bailly-Salins, B. Baret, A. Bariego-Quintana, Y. Becherini, M. Bendahman, F. Benfenati Gualandi, M. Benhassi, D. M. Benoit, Z. Beňušová, E. Berbee, E. Berti , et al. (263 additional authors not shown)

Abstract: The existence of an eV-scale sterile neutrino has been proposed to explain several anomalous experimental results obtained over the course of the past 25 years. The first search for such a sterile neutrino conducted with data from KM3NeT/ORCA -- a water Cherenkov neutrino telescope under construction at the bottom of the Mediterranean Sea -- is reported in this paper. GeV-scale atmospheric neutrin… ▽ More The existence of an eV-scale sterile neutrino has been proposed to explain several anomalous experimental results obtained over the course of the past 25 years. The first search for such a sterile neutrino conducted with data from KM3NeT/ORCA -- a water Cherenkov neutrino telescope under construction at the bottom of the Mediterranean Sea -- is reported in this paper. GeV-scale atmospheric neutrino oscillations are measured by reconstructing the energy and arrival direction of up-going neutrinos that have traversed the Earth. This study is based on a data sample containing 5828 neutrino candidates collected with 6 detection units ($5\%$ of the complete detector), corresponding to an exposure of 433 kton-years. From the expected effect of an eV-scale sterile neutrino on the first $ν_μ\rightarrow ν_τ$ standard oscillation maximum, simultaneous constraints are put on the magnitude of the $U_{μ4}$ and $U_{τ4}$ mixing elements assuming $Δm^2_{41} \geq 1$ eV$^2$. The results are compatible with the absence of mixing between active neutrinos and a sterile state, with $|U_{μ4}|^2 < 0.138$ and $|U_{τ4}|^2 < 0.076$ at a $90\%$ confidence level. Such constraints are compatible with the results reported by other long-baseline experiments, and indicate that with KM3NeT/ORCA it is possible to bring crucial contributions to sterile neutrino searches in the coming years. △ Less

Submitted 21 November, 2025; v1 submitted 8 October, 2025; originally announced October 2025.

Comments: 23 pages, 6 figures; minor revisions following comments from referee

Design, waterproofing, and mass production of the 3-inch PMT frontend system of JUNO

Authors: Jilei Xu, Miao He, Cédric Cerna, Yongbo Huang, Thomas Adam, Shakeel Ahmad, Rizwan Ahmed, Fengpeng An, Costas Andreopoulos, Giuseppe Andronico, João Pedro Athayde Marcondes de André, Nikolay Anfimov, Vito Antonelli, Tatiana Antoshkina, Didier Auguste, Weidong Bai, Nikita Balashov, Andrea Barresi, Davide Basilico, Eric Baussan, Marco Beretta, Antonio Bergnoli, Nikita Bessonov, Daniel Bick, Lukas Bieger , et al. (609 additional authors not shown)

Abstract: Over 25,600 3-inch photomultiplier tubes (PMTs) have been instrumented for the central detector of the Jiangmen Underground Neutrino Observatory. Each PMT is equipped with a high-voltage divider and a frontend cable with waterproof sealing. Groups of sixteen PMTs are connected to the underwater frontend readout electronics via specialized multi-channel waterproof connectors. This paper outlines th… ▽ More Over 25,600 3-inch photomultiplier tubes (PMTs) have been instrumented for the central detector of the Jiangmen Underground Neutrino Observatory. Each PMT is equipped with a high-voltage divider and a frontend cable with waterproof sealing. Groups of sixteen PMTs are connected to the underwater frontend readout electronics via specialized multi-channel waterproof connectors. This paper outlines the design and mass production processes for the high-voltage divider, the cable and connector, as well as the waterproof potting of the PMT bases. The results of the acceptance tests of all the integrated PMTs are also presented. △ Less

Submitted 22 January, 2026; v1 submitted 7 October, 2025; originally announced October 2025.

Constraining gamma-ray burst parameters with the first ultra-high energy neutrino event KM3-230213A

Authors: KM3NeT Collaboration, O. Adriani, A. Albert, A. R. Alhebsi, S. Alshalloudi, M. Alshamsi, S. Alves Garre, A. Ambrosone, F. Ameli, M. Andre, L. Aphecetche, M. Ardid, S. Ardid, J. Aublin, F. Badaracco, L. Bailly-Salins, B. Baret, A. Bariego-Quintana, Y. Becherini, M. Bendahman, F. Benfenati Gualandi, M. Benhassi, D. M. Benoit, Beňušová, E. Berbee , et al. (256 additional authors not shown)

Abstract: Context: The detection of the highest energy neutrino observed to date by KM3NeT, with an estimated energy of 220 PeV, opens up new possibilities for the study and identification of the astrophysical sources responsible for a diffuse flux of such ultra-high-energy neutrinos, among which gamma-ray bursts are longstanding candidates. Aims: Based on the event KM3-230213A, we derive constraints on t… ▽ More Context: The detection of the highest energy neutrino observed to date by KM3NeT, with an estimated energy of 220 PeV, opens up new possibilities for the study and identification of the astrophysical sources responsible for a diffuse flux of such ultra-high-energy neutrinos, among which gamma-ray bursts are longstanding candidates. Aims: Based on the event KM3-230213A, we derive constraints on the baryon loading and density of the surrounding environment in models of blastwaves in long-duration gamma-ray bursts. Methods: We compute the diffuse flux from gamma-ray burst blastwaves, either expanding in a constant density interstellar medium or developing in a radially decreasing density of a wind-like environment surrounding the gamma-ray burst progenitor star, by taking into account the expected neutrino spectra and luminosity function. We use a Poisson likelihood method to constrain the blastwave model parameters by calculating the expected number of neutrino events within the 90% confidence level energy range of KM3-230213A and by using the joint exposure of KM3NeT/ARCA, IceCube and Pierre Auger. Results: We constrain the baryon loading to be $\leq \{392, 131, 39, 13\}$ at 90% confidence level, which is inversely proportional to a varying interstellar medium particle density of $\{1, 3, 10, 30\}$ cm$^{-3}$. In the wind-like environment case, the baryon loading is $\leq \{20, 50, 100\}$ at 90% confidence level, which is proportional to the sixth power of a varying density parameter of $\{0.05, 0.06, 0.07\}$. △ Less

Submitted 19 May, 2026; v1 submitted 18 September, 2025; originally announced September 2025.

Comments: Accepted for publication in Astronomy & Astrophysics

Journal ref: A&A 710, A168 (2026)

Simulation-based inference for Precision Neutrino Physics through Neural Monte Carlo tuning

Authors: A. Gavrikov, A. Serafini, D. Dolzhikov, A. Garfagnini, M. Gonchar, M. Grassi, R. Brugnera, V. Cerrone, L. V. D'Auria, R. M. Guizzetti, L. Lastrucci, G. Andronico, V. Antonelli, A. Barresi, D. Basilico, M. Beretta, A. Bergnoli, M. Borghesi, A. Brigatti, R. Bruno, A. Budano, B. Caccianiga, A. Cammi, R. Caruso, D. Chiesa , et al. (41 additional authors not shown)

Abstract: Precise modeling of detector energy response is crucial for next-generation neutrino experiments which present computational challenges due to lack of analytical likelihoods. We propose a solution using neural likelihood estimation within the simulation-based inference framework. We develop two complementary neural density estimators that model likelihoods of calibration data: conditional normaliz… ▽ More Precise modeling of detector energy response is crucial for next-generation neutrino experiments which present computational challenges due to lack of analytical likelihoods. We propose a solution using neural likelihood estimation within the simulation-based inference framework. We develop two complementary neural density estimators that model likelihoods of calibration data: conditional normalizing flows and a transformer-based regressor. We adopt JUNO - a large neutrino experiment - as a case study. The energy response of JUNO depends on several parameters, all of which should be tuned, given their non-linear behavior and strong correlations in the calibration data. To this end, we integrate the modeled likelihoods with Bayesian nested sampling for parameter inference, achieving uncertainties limited only by statistics with near-zero systematic biases. The normalizing flows model enables unbinned likelihood analysis, while the transformer provides an efficient binned alternative. By providing both options, our framework offers flexibility to choose the most appropriate method for specific needs. Finally, our approach establishes a template for similar applications across experimental neutrino and broader particle physics. △ Less

Submitted 31 July, 2025; originally announced July 2025.

The Online Data Filter for the KM3NeT Neutrino Telescopes

Authors: O. Adriani, S. Aiello, A. Albert, A. R. Alhebsi, M. Alshamsi, S. Alves Garre, A. Ambrosone, F. Ameli, M. Andre, L. Aphecetche, M. Ardid, S. Ardid, J. Aublin, F. Badaracco, L. Bailly-Salins, Z. Bardacova, B. Baret, A. Bariego-Quintana, Y. Becherini, M. Bendahman, F. Benfenati Gualandi, M. Benhassi, M. Bennani, D. M. Benoit, E. Berbee , et al. (257 additional authors not shown)

Abstract: The KM3NeT research infrastructure comprises two neutrino telescopes located in the deep waters of the Mediterranean Sea, namely ORCA and ARCA. KM3NeT/ORCA is designed for the measurement of neutrino properties and KM3NeT/ARCA for the detection of high-energy neutrinos from the cosmos. Neutrinos are indirectly detected using three-dimensional arrays of photo-sensors which detect the Cherenkov ligh… ▽ More The KM3NeT research infrastructure comprises two neutrino telescopes located in the deep waters of the Mediterranean Sea, namely ORCA and ARCA. KM3NeT/ORCA is designed for the measurement of neutrino properties and KM3NeT/ARCA for the detection of high-energy neutrinos from the cosmos. Neutrinos are indirectly detected using three-dimensional arrays of photo-sensors which detect the Cherenkov light that is produced when relativistic charged particles emerge from a neutrino interaction. The analogue pulses from the photo-sensors are digitised offshore and all digital data are sent to a station on shore where they are processed in real time using a farm of commodity servers and custom software. In this paper, the design and performance of the software that is used to filter the data are presented. The performance of the data filter is evaluated in terms of its efficiency, purity and capacity. The efficiency is measured by the effective volumes of the sensor arrays as a function of the energy of the neutrino. The purity is measured by a comparison of the event rate caused by muons produced by cosmic ray interactions in the Earth's atmosphere with the event rate caused by the background from decays of radioactive elements in the sea water and bioluminescence. The capacity is measured by the minimal number of servers that is needed to sustain the rate of incoming data. The results of these evaluations comply with all specifications. The count rates of all photo-sensors are measured with a sampling frequency of 10 Hz. These data are input to the simulations of the detector response and will also be made available for interdisciplinary research. △ Less

Submitted 15 October, 2025; v1 submitted 6 June, 2025; originally announced June 2025.

Comments: 29 pages, 4 figures

Old and New Results on Alphabetic Codes

Authors: Roberto Bruno, Roberto De Prisco, Ugo Vaccaro

Abstract: This comprehensive survey examines the field of alphabetic codes, tracing their development from the 1960s to the present day. We explore classical alphabetic codes and their variants, analyzing their properties and the underlying mathematical and algorithmic principles. The paper covers the fundamental relationship between alphabetic codes and comparison-based search procedures and their applicat… ▽ More This comprehensive survey examines the field of alphabetic codes, tracing their development from the 1960s to the present day. We explore classical alphabetic codes and their variants, analyzing their properties and the underlying mathematical and algorithmic principles. The paper covers the fundamental relationship between alphabetic codes and comparison-based search procedures and their applications in data compression, routing, and testing. We review optimal alphabetic code construction algorithms, necessary and sufficient conditions for their existence, and upper bounds on the average code length of optimal alphabetic codes. The survey also discusses variations and generalizations of the classical problem of constructing minimum average length alphabetic codes. By elucidating both classical results and recent findings, this paper aims to serve as a valuable resource for researchers and students, concluding with promising future research directions in this still-active field. △ Less

Submitted 8 April, 2025; originally announced April 2025.

Comments: Published in: Information Theory and Related Fields, Lecture Notes in Computer Science

Journal ref: Information Theory and Related Fields, Lecture Notes in Computer Science, Springer, vol. 14620, pp. 151-194, 2025

Simulation of the Background from $^{13}$C$(α, n)^{16}$O Reaction in the JUNO Scintillator

Authors: JUNO Collaboration, Thomas Adam, Kai Adamowicz, Shakeel Ahmad, Rizwan Ahmed, Sebastiano Aiello, Fengpeng An, Costas Andreopoulos, Giuseppe Andronico, Nikolay Anfimov, Vito Antonelli, Tatiana Antoshkina, João Pedro Athayde Marcondes de André, Didier Auguste, Weidong Bai, Nikita Balashov, Andrea Barresi, Davide Basilico, Eric Baussan, Marco Beretta, Antonio Bergnoli, Nikita Bessonov, Daniel Bick, Lukas Bieger, Svetlana Biktemerova , et al. (608 additional authors not shown)

Abstract: Large-scale organic liquid scintillator detectors are highly efficient in the detection of MeV-scale electron antineutrinos. These signal events can be detected through inverse beta decay on protons, which produce a positron accompanied by a neutron. A noteworthy background for antineutrinos coming from nuclear power reactors and from the depths of the Earth (geoneutrinos) is generated by ($α, n$)… ▽ More Large-scale organic liquid scintillator detectors are highly efficient in the detection of MeV-scale electron antineutrinos. These signal events can be detected through inverse beta decay on protons, which produce a positron accompanied by a neutron. A noteworthy background for antineutrinos coming from nuclear power reactors and from the depths of the Earth (geoneutrinos) is generated by ($α, n$) reactions. In organic liquid scintillator detectors, $α$ particles emitted from intrinsic contaminants such as $^{238}$U, $^{232}$Th, and $^{210}$Pb/$^{210}$Po, can be captured on $^{13}$C nuclei, followed by the emission of a MeV-scale neutron. Three distinct interaction mechanisms can produce prompt energy depositions preceding the delayed neutron capture, leading to a pair of events correlated in space and time within the detector. Thus, ($α, n$) reactions represent an indistinguishable background in liquid scintillator-based antineutrino detectors, where their expected rate and energy spectrum are typically evaluated via Monte Carlo simulations. This work presents results from the open-source SaG4n software, used to calculate the expected energy depositions from the neutron and any associated de-excitation products. Also simulated is a detailed detector response to these interactions, using a dedicated Geant4-based simulation software from the JUNO experiment. An expected measurable $^{13}$C$(α, n)^{16}$O event rate and reconstructed prompt energy spectrum with associated uncertainties, are presented in the context of JUNO, however, the methods and results are applicable and relevant to other organic liquid scintillator neutrino detectors. △ Less

Submitted 2 May, 2025; v1 submitted 2 March, 2025; originally announced March 2025.

Comments: 25 pages, 14 figures, 4 tables

The dynamics of small-scale magnetic fields modulated by the solar cycle

Authors: M. Stangalini, G. Verth, V. Fedun, D. Perrone, M. Berretti, P. Bushby, S. Jafarzadeh, D. B. Jess, F. Giannattasio, P. H. Keys, R. Bruno, F. Berrilli

Abstract: In addition to sunspots, which represent the most easily visualized manifestation of solar magnetism, cutting-edge observations of the solar atmosphere have uncovered a plethora of magnetic flux tubes, down to the resolving power of modern high-resolution telescopes (a few tens of km), revealing how the Sun is a fully magnetized star. These magnetic elements are advected and buffeted by ambient pl… ▽ More In addition to sunspots, which represent the most easily visualized manifestation of solar magnetism, cutting-edge observations of the solar atmosphere have uncovered a plethora of magnetic flux tubes, down to the resolving power of modern high-resolution telescopes (a few tens of km), revealing how the Sun is a fully magnetized star. These magnetic elements are advected and buffeted by ambient plasma flows and turbulent convection, resulting in perturbations of the flux tubes that make them natural conduits for channeling wave energy into the upper layers of the Sun's atmosphere and significantly contributing to the acceleration of the solar wind. Today, data acquired by the Helioseismic and Magnetic Imager (HMI) onboard NASA's Solar Dynamics Observatory (SDO), have made it possible to study the dynamics of small-scale magnetic fields over long timescales. Here, for the first time, we present the discovery of a modulation in the dynamical behavior of small-scale magnetic concentrations in the photosphere over temporal scales consistent with the solar activity cycle (i.e. 11 years), which has only been made possible by the long observing lifetime of the SDO/HMI spacecraft. Furthermore, a temporal varying polarization of their perturbations is also found on similar timescales. This demonstrates how the small-scale dynamics of magnetic fields are also affected by the global dynamo. These discoveries were realized through automated tracking of magnetic fields in the solar photosphere across 11 continuous years, resulting in the most extended statistical analyses of its kind so far, with more than 31 million magnetic concentrations examined. △ Less

Submitted 26 February, 2025; originally announced February 2025.

Comments: Accepted in A&A Letters

CRIUgpu: Transparent Checkpointing of GPU-Accelerated Workloads

Authors: Radostin Stoyanov, Viktória Spišaková, Jesus Ramos, Steven Gurfinkel, Andrei Vagin, Adrian Reber, Wesley Armour, Rodrigo Bruno

Abstract: Deep learning training at scale is resource-intensive and time-consuming, often running across hundreds or thousands of GPUs for weeks or months. Efficient checkpointing is crucial for running these workloads, especially in multi-tenant environments where compute resources are shared, and job preemptions or interruptions are common. However, transparent and unified GPU snapshots are particularly c… ▽ More Deep learning training at scale is resource-intensive and time-consuming, often running across hundreds or thousands of GPUs for weeks or months. Efficient checkpointing is crucial for running these workloads, especially in multi-tenant environments where compute resources are shared, and job preemptions or interruptions are common. However, transparent and unified GPU snapshots are particularly challenging because of the hardware architecture differences between CPU and GPU, including memory subsystems, dynamic parallelism, and thread synchronization. State-of-the-art GPU checkpointing techniques typically leverage mechanisms that intercept, log, and replay device API calls. However, this approach adds performance overhead and requires hardware-specific implementation that is difficult to test, maintain, and integrate with existing container platforms. In this paper, we present CRIUgpu - a novel approach for transparent checkpointing of GPU-accelerated workloads that builds on recently introduced driver capabilities, enabling support for CUDA and ROCm applications. Our evaluation results show that CRIUgpu works with a variety of deep learning and high-performance computing workloads running across multiple GPUs, completely eliminating steady-state performance overheads, and significantly reducing recovery times compared to state-of-the-art transparent GPU checkpointing mechanisms. △ Less

Submitted 23 February, 2025; originally announced February 2025.

KM3NeT Constraint on Lorentz-Violating Superluminal Neutrino Velocity

Authors: KM3NeT Collaboration, O. Adriani, S. Aiello, A. Albert, A. R. Alhebsi, M. Alshamsi, S. Alves Garre, A. Ambrosone, F. Ameli, M. Andre, L. Aphecetche, M. Ardid, S. Ardid, C. Argüelles, J. Aublin, F. Badaracco, L. Bailly-Salins, Z. Bardačová, A. Bariego-Quintana, Y. Becherini, M. Bendahman, F. Benfenati Gualandi, M. Benhassi, M. Bennani, D. M. Benoit , et al. (268 additional authors not shown)

Abstract: Lorentz invariance is a fundamental symmetry of spacetime and foundational to modern physics. One of its most important consequences is the constancy of the speed of light. This invariance, together with the geometry of spacetime, implies that no particle can move faster than the speed of light. In this article, we present the most stringent neutrino-based test of this prediction, using the highes… ▽ More Lorentz invariance is a fundamental symmetry of spacetime and foundational to modern physics. One of its most important consequences is the constancy of the speed of light. This invariance, together with the geometry of spacetime, implies that no particle can move faster than the speed of light. In this article, we present the most stringent neutrino-based test of this prediction, using the highest energy neutrino ever detected to date, KM3-230213A. The arrival of this event, with an energy of $220^{+570}_{-110}\,\text{PeV}$, sets a constraint on $δ\equiv c_ν^2-1 < 4\times10^{-22}$. △ Less

Submitted 24 February, 2025; v1 submitted 17 February, 2025; originally announced February 2025.

Towards End-to-End Application Slicing in Multi-access Edge Computing systems: Architecture Discussion and Proof-of-Concept

Authors: Simone Bolettieri, Dinh Thai Bui, Raffaele Bruno

Abstract: Network slicing is one of the most critical 5G pillars. It allows for sharing a 5G infrastructure among different tenants leading to improved service customisation and increased operators' revenues. Concurrently, introducing the Multi-access Edge Computing (MEC) into 5G to support time-critical applications raises the need to integrate this distributed computing infrastructure to the 5G network sl… ▽ More Network slicing is one of the most critical 5G pillars. It allows for sharing a 5G infrastructure among different tenants leading to improved service customisation and increased operators' revenues. Concurrently, introducing the Multi-access Edge Computing (MEC) into 5G to support time-critical applications raises the need to integrate this distributed computing infrastructure to the 5G network slicing framework. Indeed, end-to-end latency guarantees require the end-to-end management of slice resources. For this purpose, after discussing the main gaps in the state-of-the-art with regards to such an objective, we propose a novel slicing architecture that enables the management and orchestration of slice segments that span over all the domains of an end-to-end application service, including the MEC. We also show how this general management architecture can be instantiated into a multi-tenant MEC infrastructure. A preliminary implementation of the proposed architecture focusing on the MEC domain is also provided, together with performance tests to validate the feasibility and efficacy of our design approach. △ Less

Submitted 15 February, 2025; originally announced February 2025.

Journal ref: Future Generation Computer Systems, Volume 136, November 2022, Pages 110-127

SLICES, a scientific instrument for the networking community

Authors: Serge Fdida, Nikos Makris, Thanasis Korakis, Raffaele Bruno, Andrea Passarella, Panayiotis Andreou, Bartosz Belter, Cedric Crettaz, Walid Dabbous, Yuri Demchenko, Raymond Knopp

Abstract: A science is defined by a set of encyclopedic knowledge related to facts or phenomena following rules or evidenced by experimentally-driven observations. Computer Science and in particular computer networks is a relatively new scientific domain maturing over years and adopting the best practices inherited from more fundamental disciplines. The design of past, present and future networking componen… ▽ More A science is defined by a set of encyclopedic knowledge related to facts or phenomena following rules or evidenced by experimentally-driven observations. Computer Science and in particular computer networks is a relatively new scientific domain maturing over years and adopting the best practices inherited from more fundamental disciplines. The design of past, present and future networking components and architectures have been assisted, among other methods, by experimentally-driven research and in particular by the deployment of test platforms, usually named as testbeds. However, often experimentally-driven networking research used scattered methodologies, based on ad-hoc, small-sized testbeds, producing hardly repeatable results. We believe that computer networks needs to adopt a more structured methodology, supported by appropriate instruments, to produce credible experimental results supporting radical and incremental innovations. This paper reports lessons learned from the design and operation of test platforms for the scientific community dealing with digital infrastructures. We introduce the SLICES initiative as the outcome of several years of evolution of the concept of a networking test platform transformed into a scientific instrument. We address the challenges, requirements and opportunities that our community is facing to manage the full research-life cycle necessary to support a scientific methodology. △ Less

Submitted 13 February, 2025; originally announced February 2025.

Journal ref: Volume 193, 1 September 2022, Pages 189-203

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

Authors: O. Adriani, S. Aiello, A. Albert, A. R. Alhebsi, M. Alshamsi, S. Alves Garre, A. Ambrosone, F. Ameli, M. Andre, L. Aphecetche, M. Ardid, S. Ardid, J. Aublin, F. Badaracco, L. Bailly-Salins, Z. Bardačová, B. Baret, A. Bariego-Quintana, Y. Becherini, M. Bendahman, F. Benfenati Gualandi, M. Benhassi, M. Bennani, D. M. Benoit, E. Berbee , et al. (264 additional authors not shown)

Abstract: The KM3NeT observatory detected the most energetic neutrino candidate ever observed, with an energy between 72 PeV and 2.6 EeV at the 90% confidence level. The observed neutrino is likely of cosmic origin. In this article, it is investigated if the neutrino could have been produced within the Milky Way. Considering the low fluxes of the Galactic diffuse emission at these energies, the lack of a ne… ▽ More The KM3NeT observatory detected the most energetic neutrino candidate ever observed, with an energy between 72 PeV and 2.6 EeV at the 90% confidence level. The observed neutrino is likely of cosmic origin. In this article, it is investigated if the neutrino could have been produced within the Milky Way. Considering the low fluxes of the Galactic diffuse emission at these energies, the lack of a nearby potential Galactic particle accelerator in the direction of the event and the difficulty to accelerate particles to such high energies in Galactic systems, we conclude that if the event is indeed cosmic, it is most likely of extragalactic origin. △ Less

Submitted 14 February, 2025; v1 submitted 12 February, 2025; originally announced February 2025.

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

Authors: KM3NeT Collaboration, O. Adriani, S. Aiello, A. Albert, A. R. Alhebsi, M. Alshamsi, S. Alves Garre, A. Ambrosone, F. Ameli, M. Andre, L. Aphecetche, M. Ardid, S. Ardid, C. Argüelles, J. Aublin, F. Badaracco, L. Bailly-Salins, Z. Bardačová, B. Baret, A. Bariego-Quintana, Y. Becherini, M. Bendahman, F. Benfenati Gualandi, M. Benhassi, M. Bennani , et al. (268 additional authors not shown)

Abstract: On February 13th, 2023, the KM3NeT/ARCA telescope detected a neutrino candidate with an estimated energy in the hundreds of PeVs. In this article, the observation of this ultra-high-energy neutrino is discussed in light of null observations above tens of PeV from the IceCube and Pierre Auger observatories. Performing a joint fit of all experiments under the assumption of an isotropic $E^{-2}$ flux… ▽ More On February 13th, 2023, the KM3NeT/ARCA telescope detected a neutrino candidate with an estimated energy in the hundreds of PeVs. In this article, the observation of this ultra-high-energy neutrino is discussed in light of null observations above tens of PeV from the IceCube and Pierre Auger observatories. Performing a joint fit of all experiments under the assumption of an isotropic $E^{-2}$ flux, the best-fit single-flavour flux normalisation is $E^2 Φ^{\rm 1f}_{ν+ \bar ν} = 7.5 \times 10^{-10}~{\rm GeV cm^{-2} s^{-1} sr^{-1}}$ in the 90% energy range of the KM3NeT event. Furthermore, the ultra-high-energy data are then fit together with the IceCube measurements at lower energies, either with a single power law or with a broken power law, allowing for the presence of a new component in the spectrum. The joint fit including non-observations by other experiments in the ultra-high-energy region shows a slight preference for a break in the PeV regime if the ``High-Energy Starting Events'' sample is included, and no such preference for the other two IceCube samples investigated. A stronger preference for a break appears if only the KM3NeT data is considered in the ultra-high-energy region, though the flux resulting from such a fit would be inconsistent with null observations from IceCube and Pierre Auger. In all cases, the observed tension between KM3NeT and other datasets is of the order of $2.5σ-3σ$, and increased statistics are required to resolve this apparent tension and better characterise the neutrino landscape at ultra-high energies. △ Less

Submitted 12 February, 2025; originally announced February 2025.

Comments: 11 pages, 4 figures

Study of tau neutrinos and non-unitary neutrino mixing with the first six detection units of KM3NeT/ORCA

Authors: KM3NeT Collaboration, S. Aiello, A. Albert, A. R. Alhebsi, M. Alshamsi, S. Alves Garre, A. Ambrosone, F. Ameli, M. Andre, L. Aphecetche, M. Ardid, S. Ardid, J. Aublin, F. Badaracco, L. Bailly-Salins, Z. Bardačová, B. Baret, A. Bariego-Quintana, Y. Becherini, M. Bendahman, F. Benfenati Gualandi, M. Benhassi, M. Bennani, D. M. Benoit, E. Berbee , et al. (252 additional authors not shown)

Abstract: Oscillations of atmospheric muon and electron neutrinos produce tau neutrinos with energies in the GeV range, which can be observed by the ORCA detector of the KM3NeT neutrino telescope in the Mediterranean Sea. First measurements with ORCA6, an early subarray corresponding to about 5$\%$ of the final detector, are presented. A sample of 5828 neutrino candidates has been selected from the analysed… ▽ More Oscillations of atmospheric muon and electron neutrinos produce tau neutrinos with energies in the GeV range, which can be observed by the ORCA detector of the KM3NeT neutrino telescope in the Mediterranean Sea. First measurements with ORCA6, an early subarray corresponding to about 5$\%$ of the final detector, are presented. A sample of 5828 neutrino candidates has been selected from the analysed exposure of 433 kton-years. The $ν_τ$ normalisation, defined as the ratio between the number of observed and expected tau neutrino events, is measured to be $S_τ= 0.48^{+0.5}_{-0.33}$. This translates into a $ν_τ$ charged-current cross section measurement of $σ_τ^{\text{meas}} = (2.5 ^{+2.6}_{-1.8}) \times 10^{-38}$ cm$^{2}$ nucleon$^{-1}$ at the median $ν_τ$ energy of 20.3 GeV. The result is consistent with the measurements of other experiments. In addition, the current limit on the non-unitarity parameter affecting the $τ$-row of the neutrino mixing matrix was improved, with $α_{33}>$ 0.95 at the 95$\%$ confidence level. △ Less

Submitted 30 April, 2025; v1 submitted 3 February, 2025; originally announced February 2025.

Comments: 25 pages, 8 figures

Application-Aware Resource Allocation and Data Management for MEC-assisted IoT Service Providers

Authors: Simone Bolettieri, Raffaele Bruno, Enzo Mingozzi

Abstract: To support the growing demand for data-intensive and low-latency IoT applications, Multi-Access Edge Computing (MEC) is emerging as an effective edge-computing approach enabling the execution of delay-sensitive processing tasks close to end-users. However, most of the existing works on resource allocation and service placement in MEC systems overlook the unique characteristics of new IoT use cases… ▽ More To support the growing demand for data-intensive and low-latency IoT applications, Multi-Access Edge Computing (MEC) is emerging as an effective edge-computing approach enabling the execution of delay-sensitive processing tasks close to end-users. However, most of the existing works on resource allocation and service placement in MEC systems overlook the unique characteristics of new IoT use cases. For instance, many IoT applications require the periodic execution of computing tasks on real-time data streams that originate from devices dispersed over a wide area. Thus, users requesting IoT services are typically distant from the data producers. To fill this gap, the contribution of this work is two-fold. Firstly, we propose a MEC-compliant architectural solution to support the operation of multiple IoT service providers over a common MEC platform deployment, which enables the steering and shaping of IoT data transport within the platform. Secondly, we model the problem of service placement and data management in the proposed MEC-based solution taking into account the dependencies at the data level between IoT services and sensing resources. Our model also considers that caches can be deployed on MEC hosts, to allow the sharing of the same data between different IoT services with overlapping geographical scope, and provides support for IoT services with heterogeneous QoS requirements, such as different frequencies of periodic task execution. Due to the complexity of the optimisation problem, a heuristic algorithm is proposed using linear relaxation and rounding techniques. Extensive simulation results demonstrate the efficiency of the proposed approach, especially when traffic demands generated by the service requests are not uniform. △ Less

Submitted 24 January, 2025; originally announced January 2025.

Journal ref: Journal of Network and Computer Applications, Volume 181, 1 May 2021, 103020

A Multi-stage Optimisation Approach to Design Relocation Strategies in One-way Car-sharing Systems with Stackable Cars

Authors: Riccardo Iacobucci, Raffaele Bruno, Chiara Boldrini

Abstract: One of the main operational challenges faced by the operators of one-way car-sharing systems is to ensure vehicle availability across the regions of the service areas with uneven patterns of rental requests. Fleet balancing strategies are required to maximise the demand served while minimising the relocation costs. However, the design of optimal relocation policies is a complex problem, and global… ▽ More One of the main operational challenges faced by the operators of one-way car-sharing systems is to ensure vehicle availability across the regions of the service areas with uneven patterns of rental requests. Fleet balancing strategies are required to maximise the demand served while minimising the relocation costs. However, the design of optimal relocation policies is a complex problem, and global optimisation solutions are often limited to very small network sizes for computational reasons. In this work, we propose a multi-stage decision support system for vehicle relocation that decomposes the general relocation problem into three independent decision stages to allow scalable solutions. Furthermore, we adopt a rolling horizon control strategy to cope with demand uncertainty. Our approach is highly modular and flexible, and we leverage it to design user-based, operator-based and robotic relocation schemes. Besides, we formulate the relocation problem considering both conventional cars and a new class of compact stackable vehicles that can be driven in a road train. We compare the proposed relocation schemes with two recognised benchmarks using a large data set of taxi trips in New York. Our results show that our approach is scalable and outperforms the benchmark schemes in terms of quality of service, vehicle utilisation and relocation efficiency. Furthermore, we find that stackable vehicles can achieve a relocation performance close to that of autonomous cars, even with a small workforce of relocators. △ Less

Submitted 23 January, 2025; originally announced January 2025.

Journal ref: IEEE Transactions on Intelligent Transportation Systems, vol. 23, no. 10, pp. 17048-17061, Oct. 2022

Probing invisible neutrino decay with the first six detection units of KM3NeT/ORCA

Authors: S. Aiello, A. Albert, A. R. Alhebsi, M. Alshamsi, S. Alves Garre, A. Ambrosone, F. Ameli, M. Andre, L. Aphecetche, M. Ardid, S. Ardid, J. Aublin, F. Badaracco, L. Bailly-Salins, Z. Bardačová, B. Baret, A. Bariego-Quintana, Y. Becherini, M. Bendahman, F. Benfenati Gualandi, M. Benhassi, M. Bennani, D. M. Benoit, E. Berbee, V. Bertin , et al. (251 additional authors not shown)

Abstract: In the era of precision measurements of neutrino oscillation parameters, it is necessary for experiments to disentangle discrepancies that may indicate physics beyond the Standard Model in the neutrino sector. KM3NeT/ORCA is a water Cherenkov neutrino detector under construction and anchored at the bottom of the Mediterranean Sea. The detector is designed to study the oscillations of atmospheric n… ▽ More In the era of precision measurements of neutrino oscillation parameters, it is necessary for experiments to disentangle discrepancies that may indicate physics beyond the Standard Model in the neutrino sector. KM3NeT/ORCA is a water Cherenkov neutrino detector under construction and anchored at the bottom of the Mediterranean Sea. The detector is designed to study the oscillations of atmospheric neutrinos and determine the neutrino mass ordering. This paper focuses on the initial configuration of ORCA, referred to as ORCA6, which comprises six out of the foreseen 115 detection units of photosensors. A high-purity neutrino sample was extracted during 2020 and 2021, corresponding to an exposure of 433 kton-years. This sample is analysed following a binned log-likelihood approach to search for invisible neutrino decay, in a three-flavour neutrino oscillation scenario, where the third neutrino mass state $ν_3$ decays into an invisible state, e.g. a sterile neutrino. The resulting best fit of the invisible neutrino decay parameter is $α_3 = 0.92^{+1.08}_{-0.57}\times 10^{-4}~\mathrm{eV^2}$, corresponding to a scenario with $θ_{23}$ in the second octant and normal neutrino mass ordering. The results are consistent with the Standard Model, within a $2.1\,σ$ interval. △ Less

Submitted 17 March, 2025; v1 submitted 20 January, 2025; originally announced January 2025.

Comments: 22 pages, 9 figures

Optimal Binary Variable-Length Codes with a Bounded Number of 1's per Codeword: Design, Analysis, and Applications

Authors: Roberto Bruno, Roberto De Prisco, Ugo Vaccaro

Abstract: In this paper, we consider the problem of constructing optimal average-length binary codes under the constraint that each codeword must contain at most $D$ ones, where $D$ is a given input parameter. We provide an $O(n^2D)$-time complexity algorithm for the construction of such codes, where $n$ is the number of codewords. We also describe several scenarios where the need to design these kinds of c… ▽ More In this paper, we consider the problem of constructing optimal average-length binary codes under the constraint that each codeword must contain at most $D$ ones, where $D$ is a given input parameter. We provide an $O(n^2D)$-time complexity algorithm for the construction of such codes, where $n$ is the number of codewords. We also describe several scenarios where the need to design these kinds of codes naturally arises. We also provide a Kraft-like inequality for the existence of (optimal) variable-length binary codes, subject to the above-described constraint on the number of 1's in each codeword. △ Less

Submitted 2 December, 2025; v1 submitted 19 January, 2025; originally announced January 2025.

Comments: Unfortunately, we have to withdraw the claim in Theorem 2, since its proof contains a flaw

Fluorescence emission of the JUNO liquid scintillator

Authors: M. Beretta, F. Houria, F. Ferraro, D. Basilico, A. Brigatti, B. Caccianiga, A. Caslini, C. Landini, P. Lombardi, L. Pelicci, E. Percalli, G. Ranucci, A. C. Re, C. Clementi, F. Ortica, A. Romani, V. Antonelli, M. G. Giammarchi, L. Miramonti, P. Saggese, M. D. C. Torri, S. Aiello, G. Andronico, A. Barresi, A. Bergnoli , et al. (43 additional authors not shown)

Abstract: JUNO is a huge neutrino detector that will use 20 kton of organic liquid scintillator as its detection medium. The scintillator is a mixture of linear alkyl benzene (LAB), 2.5 g/L of 2,5-diphenyloxazole (PPO) and 3 mg/L of 1,4-Bis(2-methylstyryl)benzene (Bis-MSB). The main goal of JUNO is to determine the Neutrino Mass Ordering [1, 2, 3]. In order to achieve this purpose, good energy and position… ▽ More JUNO is a huge neutrino detector that will use 20 kton of organic liquid scintillator as its detection medium. The scintillator is a mixture of linear alkyl benzene (LAB), 2.5 g/L of 2,5-diphenyloxazole (PPO) and 3 mg/L of 1,4-Bis(2-methylstyryl)benzene (Bis-MSB). The main goal of JUNO is to determine the Neutrino Mass Ordering [1, 2, 3]. In order to achieve this purpose, good energy and position reconstruction is required, hence a complete understanding of the optical characteristics of the liquid scintillator is mandatory. In this paper we present the measurements on the JUNO scintillator emission spectrum, absorption length and fluorescence time distribution performed respectively with a spectrofluorimeter, a spectrophotometer and a custom made setup △ Less

Submitted 9 March, 2025; v1 submitted 17 January, 2025; originally announced January 2025.

Journal ref: Journal of Instrumentation, Volume 20, May 2025

Impact of Two-Population $α$-particle Distributions on Plasma Stability

Authors: Mihailo M. Martinović, Kristopher G. Klein, Rossana De Marco, Daniel Verscharen, Raffaella D'Amicis, Roberto Bruno

Abstract: The stability of weakly collisional plasmas is well represented by linear theory, and the generated waves play an essential role in the thermodynamics of these systems. The velocity distribution functions (VDF) characterizing kinetic particle behavior are commonly represented as a sum of anisotropic bi-Maxwellians. For the majority of in situ observations of solar wind plasmas enabled by heliosphe… ▽ More The stability of weakly collisional plasmas is well represented by linear theory, and the generated waves play an essential role in the thermodynamics of these systems. The velocity distribution functions (VDF) characterizing kinetic particle behavior are commonly represented as a sum of anisotropic bi-Maxwellians. For the majority of in situ observations of solar wind plasmas enabled by heliospheric missions, a three bi-Maxwellian model is commonly applied for the ions, assuming that the VDF consists of a proton core, proton beam, and a single He ($α$) particle population, each with their own density, bulk velocity, and anisotropic temperature. Resolving an $α$-beam component was generally not possible due to instrumental limitations. The Solar Orbiter Solar Wind Analyser Proton and Alpha Sensor (SWA PAS) resolves velocity space with sufficient coverage and accuracy to routinely characterize secondary $α$ populations consistently. This design makes the SWA PAS dataset ideal for examining effects of the $α$-particle beam on the plasma's kinetic stability. We test the wave signatures observed in the magnetic field power spectrum at ion scales and compare them to the predictions from linear plasma theory, Doppler-shifted into the spacecraft reference frame. We find that taking into account the $α$-particle beam component is necessary to predict the coherent wave signatures in the observed power spectra, emphasizing the importance of separating the $α$-particle populations as is traditionally done for protons. Moreover, we demonstrate that the drifts of beam components are responsible for the majority of the modes that propagate in oblique direction to the magnetic field, while their temperature anisotropies are the primary source of parallel Fast Magnetosonic Modes in the solar wind. △ Less

Submitted 6 December, 2024; originally announced December 2024.

Search for non-standard neutrino interactions with the first six detection units of KM3NeT/ORCA

Authors: S. Aiello, A. Albert, A. R. Alhebsi, M. Alshamsi, S. Alves Garre, A. Ambrosone, F. Ameli, M. Andre, L. Aphecetche, M. Ardid, S. Ardid, J. Aublin, F. Badaracco, L. Bailly-Salins, Z. Bardačová, B. Baret, A. Bariego-Quintana, Y. Becherini, M. Bendahman, F. Benfenati, M. Benhassi, M. Bennani, D. M. Benoit, E. Berbee, V. Bertin , et al. (239 additional authors not shown)

Abstract: KM3NeT/ORCA is an underwater neutrino telescope under construction in the Mediterranean Sea. Its primary scientific goal is to measure the atmospheric neutrino oscillation parameters and to determine the neutrino mass ordering. ORCA can constrain the oscillation parameters $Δm^{2}_{31}$ and $θ_{23}$ by reconstructing the arrival direction and energy of multi-GeV neutrinos crossing the Earth. Searc… ▽ More KM3NeT/ORCA is an underwater neutrino telescope under construction in the Mediterranean Sea. Its primary scientific goal is to measure the atmospheric neutrino oscillation parameters and to determine the neutrino mass ordering. ORCA can constrain the oscillation parameters $Δm^{2}_{31}$ and $θ_{23}$ by reconstructing the arrival direction and energy of multi-GeV neutrinos crossing the Earth. Searches for deviations from the Standard Model of particle physics in the forward scattering of neutrinos inside Earth matter, produced by Non-Standard Interactions, can be conducted by investigating distortions of the standard oscillation pattern of neutrinos of all flavours. This work reports on the results of the search for non-standard neutrino interactions using the first six detection units of ORCA and 433 kton-years of exposure. No significant deviation from standard interactions was found in a sample of 5828 events reconstructed in the 1 GeV$-$1 TeV energy range. The flavour structure of the non-standard coupling was constrained at 90\% confidence level to be $|\varepsilon_{μτ} | \leq 5.4 \times 10^{-3}$, $|\varepsilon_{eτ} | \leq 7.4 \times 10^{-2}$, $|\varepsilon_{eμ} | \leq 5.6 \times 10^{-2}$ and $-0.015 \leq \varepsilon_{ττ} - \varepsilon_{μμ} \leq 0.017$. The results are comparable to the current most stringent limits placed on the parameters by other experiments. △ Less

Submitted 22 January, 2025; v1 submitted 28 November, 2024; originally announced November 2024.

First Searches for Dark Matter with the KM3NeT Neutrino Telescopes

Authors: KM3NeT Collaboration, S. Aiello, A. Albert, A. R. Alhebsi, M. Alshamsi, S. Alves Garre, A. Ambrosone, F. Ameli, M. Andre, L. Aphecetche, M. Ardid, S. Ardid, J. Aublin, F. Badaracco, L. Bailly-Salins, Z. Bardačová, B. Baret, A. Bariego-Quintana, Y. Becherini, M. Bendahman, F. Benfenati, M. Benhassi, M. Bennani, D. M. Benoit, E. Berbee , et al. (240 additional authors not shown)

Abstract: Indirect dark matter detection methods are used to observe the products of dark matter annihilations or decays originating from astrophysical objects where large amounts of dark matter are thought to accumulate. With neutrino telescopes, an excess of neutrinos is searched for in nearby dark matter reservoirs, such as the Sun and the Galactic Centre, which could potentially produce a sizeable flux… ▽ More Indirect dark matter detection methods are used to observe the products of dark matter annihilations or decays originating from astrophysical objects where large amounts of dark matter are thought to accumulate. With neutrino telescopes, an excess of neutrinos is searched for in nearby dark matter reservoirs, such as the Sun and the Galactic Centre, which could potentially produce a sizeable flux of Standard Model particles. The KM3NeT infrastructure, currently under construction, comprises the ARCA and ORCA undersea Čerenkov neutrino detectors located at two different sites in the Mediterranean Sea, offshore of Italy and France, respectively. The two detector configurations are optimised for the detection of neutrinos of different energies, enabling the search for dark matter particles with masses ranging from a few GeV/c$^2$ to hundreds of TeV/c$^2$. In this work, searches for dark matter annihilations in the Galactic Centre and the Sun with data samples taken with the first configurations of both detectors are presented. No significant excess over the expected background was found in either of the two analyses. Limits on the velocity-averaged self-annihilation cross section of dark matter particles are computed for five different primary annihilation channels in the Galactic Centre. For the Sun, limits on the spin-dependent and spin-independent scattering cross sections of dark matter with nucleons are given for three annihilation channels. △ Less

Submitted 17 February, 2025; v1 submitted 15 November, 2024; originally announced November 2024.

gSeaGen code by KM3NeT: an efficient tool to propagate muons simulated with CORSIKA

Authors: S. Aiello, A. Albert, A. R. Alhebsi, M. Alshamsi, S. Alves Garre, A. Ambrosone, F. Ameli, M. Andre, L. Aphecetche, M. Ardid, S. Ardid, H. Atmani, J. Aublin, F. Badaracco, L. Bailly-Salins, Z. Bardačová, B. Baret, A. Bariego-Quintana, Y. Becherini, M. Bendahman, F. Benfenati, M. Benhassi, M. Bennani, D. M. Benoit, E. Berbee , et al. (238 additional authors not shown)

Abstract: The KM3NeT Collaboration has tackled a common challenge faced by the astroparticle physics community, namely adapting the experiment-specific simulation software to work with the CORSIKA air shower simulation output. The proposed solution is an extension of the open source code gSeaGen, which allows the transport of muons generated by CORSIKA to a detector of any size at an arbitrary depth. The gS… ▽ More The KM3NeT Collaboration has tackled a common challenge faced by the astroparticle physics community, namely adapting the experiment-specific simulation software to work with the CORSIKA air shower simulation output. The proposed solution is an extension of the open source code gSeaGen, which allows the transport of muons generated by CORSIKA to a detector of any size at an arbitrary depth. The gSeaGen code was not only extended in terms of functionality but also underwent a thorough redesign of the muon propagation routine, resulting in a more accurate and efficient simulation. This paper presents the capabilities of the new gSeaGen code as well as prospects for further developments. △ Less

Submitted 29 April, 2025; v1 submitted 31 October, 2024; originally announced October 2024.

Comments: 31 pages, 13 figures, accepted for publication in Computer Physics Communications

Journal ref: Computer Physics Communications Volume 314, September 2025, 109660

Search for quantum decoherence in neutrino oscillations with six detection units of KM3NeT/ORCA

Authors: S. Aiello, A. Albert, A. R. Alhebsi, M. Alshamsi, S. Alves Garre, A. Ambrosone, F. Ameli, M. Andre, L. Aphecetche, M. Ardid, S. Ardid, H. Atmani, J. Aublin, F. Badaracco, L. Bailly-Salins, Z. Bardacova, B. Baret, A. Bariego-Quintana, Y. Becherini, M. Bendahman, F. Benfenati, M. Benhassi, M. Bennani, D. M. Benoit, E. Berbee , et al. (237 additional authors not shown)

Abstract: Neutrinos described as an open quantum system may interact with the environment which introduces stochastic perturbations to their quantum phase. This mechanism leads to a loss of coherence along the propagation of the neutrino $-$ a phenomenon commonly referred to as decoherence $-$ and ultimately, to a modification of the oscillation probabilities. Fluctuations in space-time, as envisaged by var… ▽ More Neutrinos described as an open quantum system may interact with the environment which introduces stochastic perturbations to their quantum phase. This mechanism leads to a loss of coherence along the propagation of the neutrino $-$ a phenomenon commonly referred to as decoherence $-$ and ultimately, to a modification of the oscillation probabilities. Fluctuations in space-time, as envisaged by various theories of quantum gravity, are a potential candidate for a decoherence-inducing environment. Consequently, the search for decoherence provides a rare opportunity to investigate quantum gravitational effects which are usually beyond the reach of current experiments. In this work, quantum decoherence effects are searched for in neutrino data collected by the KM3NeT/ORCA detector from January 2020 to November 2021. The analysis focuses on atmospheric neutrinos within the energy range of a few GeV to $100\,\mathrm{GeV}$. Adopting the open quantum system framework, decoherence is described in a phenomenological manner with the strength of the effect given by the parameters $Γ_{21}$ and $Γ_{31}$. Following previous studies, a dependence of the type $Γ_{ij} \propto (E/E_0)^n$ on the neutrino energy is assumed and the cases $n = -2,-1$ are explored. No significant deviation with respect to the standard oscillation hypothesis is observed. Therefore, $90\,\%$ CL upper limits are estimated as $Γ_{21} < 4.6\cdot 10^{-21}\,$GeV and $Γ_{31} < 8.4\cdot 10^{-21}\,$GeV for $n = -2$, and $Γ_{21} < 1.9\cdot 10^{-22}\,$GeV and $Γ_{31} < 2.7\cdot 10^{-22}\,$GeV for $n = -1$, respectively. △ Less

Submitted 3 October, 2024; v1 submitted 2 October, 2024; originally announced October 2024.

Comments: 17 pages, 5 figures

Measurement of neutrino oscillation parameters with the first six detection units of KM3NeT/ORCA

Authors: KM3NeT Collaboration, S. Aiello, A. Albert, A. R. Alhebsi, M. Alshamsi, S. Alves Garre, A. Ambrosone, F. Ameli, M. Andre, L. Aphecetche, M. Ardid, S. Ardid, H. Atmani, J. Aublin, F. Badaracco, L. Bailly-Salins, Z. Bardačová, B. Baret, A. Bariego-Quintana, Y. Becherini, M. Bendahman, F. Benfenati, M. Benhassi, M. Bennani, D. M. Benoit , et al. (238 additional authors not shown)

Abstract: KM3NeT/ORCA is a water Cherenkov neutrino detector under construction and anchored at the bottom of the Mediterranean Sea. The detector is designed to study oscillations of atmospheric neutrinos and determine the neutrino mass ordering. This paper focuses on an initial configuration of ORCA, referred to as ORCA6, which comprises six out of the foreseen 115 detection units of photo-sensors. A high-… ▽ More KM3NeT/ORCA is a water Cherenkov neutrino detector under construction and anchored at the bottom of the Mediterranean Sea. The detector is designed to study oscillations of atmospheric neutrinos and determine the neutrino mass ordering. This paper focuses on an initial configuration of ORCA, referred to as ORCA6, which comprises six out of the foreseen 115 detection units of photo-sensors. A high-purity neutrino sample was extracted, corresponding to an exposure of 433 kton-years. The sample of 5828 neutrino candidates is analysed following a binned log-likelihood method in the reconstructed energy and cosine of the zenith angle. The atmospheric oscillation parameters are measured to be $\sin^2θ_{23}= 0.51^{+0.04}_{-0.05}$, and $ Δm^2_{31} = 2.18^{+0.25}_{-0.35}\times 10^{-3}~\mathrm{eV^2} \cup \{-2.25,-1.76\}\times 10^{-3}~\mathrm{eV^2}$ at 68\% CL. The inverted neutrino mass ordering hypothesis is disfavoured with a p-value of 0.25. △ Less

Submitted 4 October, 2024; v1 submitted 13 August, 2024; originally announced August 2024.

Comments: 29 pages, 12 figures

Bounds and Algorithms for Alphabetic Codes and Binary Search Trees

Authors: Roberto Bruno, Roberto De Prisco, Alfredo De Santis, Ugo Vaccaro

Abstract: Alphabetic codes and binary search trees are combinatorial structures that abstract search procedures in ordered sets endowed with probability distributions. In this paper, we design new linear-time algorithms to construct alphabetic codes, and we show that the obtained codes are not too far from being optimal. Moreover, we exploit our results on alphabetic codes to provide new bounds on the avera… ▽ More Alphabetic codes and binary search trees are combinatorial structures that abstract search procedures in ordered sets endowed with probability distributions. In this paper, we design new linear-time algorithms to construct alphabetic codes, and we show that the obtained codes are not too far from being optimal. Moreover, we exploit our results on alphabetic codes to provide new bounds on the average cost of optimal binary search trees. Our results improve on the best-known bounds on the average cost of optimal binary search trees present in the literature. △ Less

Submitted 23 July, 2024; originally announced July 2024.

Comments: Accepted by IEEE Transaction on Information Theory

Journal ref: IEEE Transaction on Information Theory, 2024

Hardness and Approximability of Dimension Reduction on the Probability Simplex

Authors: Roberto Bruno

Abstract: Dimension reduction is a technique used to transform data from a high-dimensional space into a lower-dimensional space, aiming to retain as much of the original information as possible. This approach is crucial in many disciplines like engineering, biology, astronomy, and economics. In this paper, we consider the following dimensionality reduction instance: Given an n-dimensional probability distr… ▽ More Dimension reduction is a technique used to transform data from a high-dimensional space into a lower-dimensional space, aiming to retain as much of the original information as possible. This approach is crucial in many disciplines like engineering, biology, astronomy, and economics. In this paper, we consider the following dimensionality reduction instance: Given an n-dimensional probability distribution p and an integer m<n, we aim to find the m-dimensional probability distribution q that is the closest to p, using the Kullback-Leibler divergence as the measure of closeness. We prove that the problem is strongly NP-hard, and we present an approximation algorithm for it. △ Less

Submitted 23 July, 2024; originally announced July 2024.

Comments: Published in Algorithms 2024, 17, 296

Journal ref: Algorithms 2024, 17(7), 296

Imaginary Machines: A Serverless Model for Cloud Applications

Authors: Michael Wawrzoniak, Rodrigo Bruno, Ana Klimovic, Gustavo Alonso

Abstract: Serverless Function-as-a-Service (FaaS) platforms provide applications with resources that are highly elastic, quick to instantiate, accounted at fine granularity, and without the need for explicit runtime resource orchestration. This combination of the core properties underpins the success and popularity of the serverless FaaS paradigm. However, these benefits are not available to most cloud appl… ▽ More Serverless Function-as-a-Service (FaaS) platforms provide applications with resources that are highly elastic, quick to instantiate, accounted at fine granularity, and without the need for explicit runtime resource orchestration. This combination of the core properties underpins the success and popularity of the serverless FaaS paradigm. However, these benefits are not available to most cloud applications because they are designed for networked virtual machines/containers environments. Since such cloud applications cannot take advantage of the highly elastic resources of serverless and require run-time orchestration systems to operate, they suffer from lower resource utilization, additional management complexity, and costs relative to their FaaS serverless counterparts. We propose Imaginary Machines, a new serverless model for cloud applications. This model (1.) exposes the highly elastic resources of serverless platforms as the traditional network-of-hosts model that cloud applications expect, and (2.) it eliminates the need for explicit run-time orchestration by transparently managing application resources based on signals generated during cloud application executions. With the Imaginary Machines model, unmodified cloud applications become serverless applications. While still based on the network-of-host model, they benefit from the highly elastic resources and do not require runtime orchestration, just like their specialized serverless FaaS counterparts, promising increased resource utilization while reducing management costs. △ Less

Submitted 30 June, 2024; originally announced July 2024.

Boxer: FaaSt Ephemeral Elasticity for Off-the-Shelf Cloud Applications

Authors: Michael Wawrzoniak, Rodrigo Bruno, Ana Klimovic, Gustavo Alonso

Abstract: Elasticity is a key property of cloud computing. However, elasticity is offered today at the granularity of virtual machines, which take tens of seconds to start. This is insufficient to react to load spikes and sudden failures in latency sensitive applications, leading users to resort to expensive overprovisioning. Function-as-a-Service (FaaS) provides significantly higher elasticity than VMs, bu… ▽ More Elasticity is a key property of cloud computing. However, elasticity is offered today at the granularity of virtual machines, which take tens of seconds to start. This is insufficient to react to load spikes and sudden failures in latency sensitive applications, leading users to resort to expensive overprovisioning. Function-as-a-Service (FaaS) provides significantly higher elasticity than VMs, but comes coupled with an event-triggered programming model and a constrained execution environment that makes them unsuitable for off-the-shelf applications. Previous work tries to overcome these obstacles but often requires re-architecting the applications. In this paper, we show how off-the-shelf applications can transparently benefit from ephemeral elasticity with FaaS. We built Boxer, an interposition layer spanning VMs and AWS Lambda, that intercepts application execution and emulates the network-of-hosts environment that applications expect when deployed in a conventional VM/container environment. The ephemeral elasticity of Boxer enables significant performance and cost savings for off-the-shelf applications with, e.g., recovery times over 5x faster than EC2 instances and absorbing load spikes comparable to overprovisioned EC2 VM instances. △ Less

Submitted 30 June, 2024; originally announced July 2024.

Interpretable machine learning approach for electron antineutrino selection in a large liquid scintillator detector

Authors: A. Gavrikov, V. Cerrone, A. Serafini, R. Brugnera, A. Garfagnini, M. Grassi, B. Jelmini, L. Lastrucci, S. Aiello, G. Andronico, V. Antonelli, A. Barresi, D. Basilico, M. Beretta, A. Bergnoli, M. Borghesi, A. Brigatti, R. Bruno, A. Budano, B. Caccianiga, A. Cammi, R. Caruso, D. Chiesa, C. Clementi, S. Dusini , et al. (43 additional authors not shown)

Abstract: Several neutrino detectors, KamLAND, Daya Bay, Double Chooz, RENO, and the forthcoming large-scale JUNO, rely on liquid scintillator to detect reactor antineutrino interactions. In this context, inverse beta decay represents the golden channel for antineutrino detection, providing a pair of correlated events, thus a strong experimental signature to distinguish the signal from a variety of backgrou… ▽ More Several neutrino detectors, KamLAND, Daya Bay, Double Chooz, RENO, and the forthcoming large-scale JUNO, rely on liquid scintillator to detect reactor antineutrino interactions. In this context, inverse beta decay represents the golden channel for antineutrino detection, providing a pair of correlated events, thus a strong experimental signature to distinguish the signal from a variety of backgrounds. However, given the low cross-section of antineutrino interactions, the development of a powerful event selection algorithm becomes imperative to achieve effective discrimination between signal and backgrounds. In this study, we introduce a machine learning (ML) model to achieve this goal: a fully connected neural network as a powerful signal-background discriminator for a large liquid scintillator detector. We demonstrate, using the JUNO detector as an example, that, despite the already high efficiency of a cut-based approach, the presented ML model can further improve the overall event selection efficiency. Moreover, it allows for the retention of signal events at the detector edges that would otherwise be rejected because of the overwhelming amount of background events in that region. We also present the first interpretable analysis of the ML approach for event selection in reactor neutrino experiments. This method provides insights into the decision-making process of the model and offers valuable information for improving and updating traditional event selection approaches. △ Less

Submitted 25 November, 2024; v1 submitted 9 June, 2024; originally announced June 2024.

Comments: This is a post-peer-review, pre-copyedit version of an article published in Phys. Lett. B. The final published version is available online: https://www.sciencedirect.com/science/article/pii/S0370269324006993

Journal ref: Physics Letters B 860, 139141 (2025)