Eur. Phys. J. C (2025) 85: 871
https://doi.org/10.1140/epjc/s10052-025-14513-2

Regular Article - Experimental Physics

Measurement of the atmospheric ${\nu }_{\mu }$ flux with six detection units of KM3NeT/ORCA

¹ INFN, Sezione di Catania, (INFN-CT), Via Santa Sofia 64, 95123, Catania, Italy
² Université de Strasbourg, CNRS, IPHC UMR 7178, 67000, Strasbourg, France
³ Department of Physics, Khalifa University of Science and Technology, PO Box 127788, Abu Dhabi, United Arab Emirates
⁴ Aix Marseille Univ, CNRS/IN2P3, CPPM, Marseille, France
⁵ IFIC-Instituto de Física Corpuscular (CSIC-Universitat de València), c/Catedrático José Beltrán, 2, 46980, Paterna, Valencia, Spain
⁶ INFN, Sezione di Napoli, Complesso Universitario di Monte S. Angelo, Via Cintia ed. G, 80126, Naples, Italy
⁷ Università di Napoli “Federico II”, Dip. Scienze Fisiche “E. Pancini”, Complesso Universitario di Monte S. Angelo, Via Cintia ed. G, 80126, Naples, Italy
⁸ INFN, Sezione di Roma, Piazzale Aldo Moro 2, 00185, Rome, Italy
⁹ Universitat Politècnica de Catalunya, Laboratori d’Aplicacions Bioacústiques, Centre Tecnològic de Vilanova i la Geltrú, Avda. Rambla Exposició, s/n, 08800, Vilanova i la Geltrú, Spain
¹⁰ Subatech, IMT Atlantique, IN2P3-CNRS, Nantes Université, BP 20722, 4 rue Alfred Kastler-La Chantrerie, 44307, Nantes, France
¹¹ Universitat Politècnica de València, Instituto de Investigación para la Gestión Integrada de las Zonas Costeras, C/ Paranimf, 1, 46730, Gandia, Spain
¹² Université Paris Cité, CNRS, Astroparticule et Cosmologie, 75013, Paris, France
¹³ Università di Genova, Via Dodecaneso 33, 16146, Genoa, Italy
¹⁴ INFN, Sezione di Genova, Via Dodecaneso 33, 16146, Genoa, Italy
¹⁵ LPC CAEN, Normandie Univ, ENSICAEN, UNICAEN, CNRS/IN2P3, 6 Boulevard Maréchal Juin, 14050, Caen, France
¹⁶ Institute of Experimental and Applied Physics, Czech Technical University in Prague, Husova 240/5, 110 00, Prague, Czech Republic
¹⁷ Department of Nuclear Physics and Biophysics, Comenius University in Bratislava, Mlynska dolina F1, 842 48, Bratislava, Slovak Republic
¹⁸ INFN, Sezione di Bologna, v.le C. Berti-Pichat, 6/2, 40127, Bologna, Italy
¹⁹ Dipartimento di Fisica e Astronomia, Università di Bologna, v.le C. Berti-Pichat, 6/2, 40127, Bologna, Italy
²⁰ Dipartimento di Matematica e Fisica, Università degli Studi della Campania “Luigi Vanvitelli”, Viale Lincoln 5, 81100, Caserta, Italy
²¹ LPC, BP 80026, Campus des Cézeaux 24, Avenue Des Landais, 63171, Aubière Cedex, France
²² E. A. Milne Centre for Astrophysics, University of Hull, HU6 7RX, Hull, UK
²³ Nikhef, National Institute for Subatomic Physics, PO Box 41882, 1009 DB, Amsterdam, Netherlands
²⁴ INFN, Laboratori Nazionali del Sud, (LNS), Via S. Sofia 62, 95123, Catania, Italy
²⁵ Centre for Space Research, North-West University, Private Bag X6001, 2520, Potchefstroom, South Africa
²⁶ Faculty of Sciences, University Mohammed V in Rabat, B.P. 1014, 4 av. Ibn Battouta, R.P. 10000, Rabat, Morocco
²⁷ Dipartimento di Fisica, Università di Salerno e INFN Gruppo Collegato di Salerno, Via Giovanni Paolo II 132, 84084, Fisciano, Italy
²⁸ ISS, Atomistilor 409, 077125, Măgurele, Romania
²⁹ Institute of Physics/IHEF, University of Amsterdam, PO Box 94216, 1090 GE, Amsterdam, Netherlands
³⁰ TNO, Technical Sciences, PO Box 155, 2600 AD, Delft, Netherlands
³¹ Dipartimento di Fisica, Università La Sapienza, Piazzale Aldo Moro 2, 00185, Rome, Italy
³² Dipartimento di Ingegneria dell’Energia Elettrica e dell’Informazione ”Guglielmo Marconi”, Università di Bologna, Via dell’Università 50, 47521, Cesena, Italy
³³ Physics Department, Faculty of Science Semlalia, Cadi Ayyad University, P.O.B. 2390, Av. My Abdellah, 40000, Marrakech, Morocco
³⁴ School of Physics, University of the Witwatersrand, Private Bag 3, 2050, Johannesburg, Wits, South Africa
³⁵ Dipartimento di Fisica e Astronomia “Ettore Majorana”, (INFN-CT), Università di Catania, Via Santa Sofia 64, 95123, Catania, Italy
³⁶ INFN, Sezione di Bari, Via Orabona, 4, 70125, Bari, Italy
³⁷ UCLouvain, Centre for Cosmology, Particle Physics and Phenomenology, Chemin du Cyclotron, 2, 1348, Louvain-la-Neuve, Belgium
³⁸ Department of Computer Engineering, Automation and Robotics/CITIC, University of Granada, 18071, Granada, Spain
³⁹ Erlangen Centre for Astroparticle Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Nikolaus-Fiebiger-Straße 2, 91058, Erlangen, Germany
⁴⁰ NCSR Demokritos, Institute of Nuclear and Particle Physics, Ag. Paraskevi Attikis, 15310, Athens, Greece
⁴¹ Faculty of Sciences, University Mohammed I, B.P. 717, BV Mohammed VI, R.P. 60000, Oujda, Morocco
⁴² School of Computing, Engineering and Mathematics, Western Sydney University, Locked Bag 1797, 2751, Penrith, NSW, Australia
⁴³ Dpto. de Física Teórica y del Cosmos & C.A.F.P.E., University of Granada, 18071, Granada, Spain
⁴⁴ NIOZ (Royal Netherlands Institute for Sea Research), PO Box 59, Den Burg, 1790 AB, Texel, the Netherlands
⁴⁵ Leiden Institute of Physics, Leiden University, PO Box 9504, 2300 RA, Leiden, Netherlands
⁴⁶ AGH University of Krakow, Al. Mickiewicza 30, 30-059, Kraków, Poland
⁴⁷ Department of Physics, Tbilisi State University, 3, Chavchavadze Ave., 0179, Tbilisi, Georgia
⁴⁸ Institute of Physics, The University of Georgia, Kostava str. 77, 0171, Tbilisi, Georgia
⁴⁹ Institut Universitaire de France, 1 Rue Descartes, 75005, Paris, France
⁵⁰ Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121, Bonn, Germany
⁵¹ University of Sharjah, Sharjah Academy for Astronomy, Space Sciences, and Technology, POB 27272, University Campus, Sharjah, United Arab Emirates
⁵² National Centre for Nuclear Research, 02-093, Warsaw, Poland
⁵³ School of Applied and Engineering Physics, Mohammed VI Polytechnic University, 43150, Ben Guerir, Morocco
⁵⁴ Department Physics, University of Johannesburg, PO Box 524, 2006, Auckland Park, South Africa
⁵⁵ Laboratoire Univers et Particules de Montpellier, Place Eugène Bataillon-CC 72, 34095, Montpellier Cédex 05, France
⁵⁶ Université de Haute Alsace, rue des Frères Lumière, 68093, Mulhouse Cedex, France
⁵⁷ Département de Physique, Faculté des Sciences, Laboratoire de Physique des Rayonnements, Université Badji Mokhtar, B. P. 12, 23000, Annaba, Algeria
⁵⁸ AstroCeNT, Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, Rektorska 4, 00-614, Warsaw, Poland
⁵⁹ Black Hole Initiative, Harvard University, 20 Garden Street, 02138, Cambridge, MA, USA
⁶⁰ Joint Institute for Nuclear Research, Dubna, Russia

^a km3net-pc@km3net.de

Received: 16 April 2025
Accepted: 11 July 2025
Published online: 13 August 2025

Abstract

A measurement of the atmospheric ${\nu }_{\mu }+{\overline{\nu }}_{\mu }$ flux with energies between 1 and 100 GeV is presented. The measurement has been performed using data taken with the first six detection units of the KM3NeT/ORCA detector, referred to as ORCA6. The data were collected between January 2020 and November 2021 and correspond to 510 days of livetime, with a total exposure of 433 kton$·$years. Using machine learning classification, 3894 neutrino candidate events have been selected with an atmospheric muon contamination of less than 1$\%$. The atmospheric ${\nu }_{\mu }+{\overline{\nu }}_{\mu }$ energy spectrum is derived using an unfolding procedure and the impact of systematic uncertainties is estimated. The atmospheric ${\nu }_{\mu }+{\overline{\nu }}_{\mu }$ flux measured using the ORCA6 configuration is in agreement with the values measured by other experiments.