It’s a major milestone for JUNO, the world's largest underground neutrino detector. After ten years of design and construction, the JUNO experiment began data collection on August 26, thanks to its central detector, to which Belgian researchers have contributed with support from the FNRS.
The international JUNO collaboration (Jiangmen Underground Neutrino Observatory), made up of around 700 researchers from 74 institutions, has commissioned the world’s largest underground neutrino detector. Located 700 meters underground near the city of Jiangmen, in Guangdong Province, China, JUNO detects antineutrinos produced 53 kilometers away by the Taishan and Yangjiang nuclear power plants, allowing it to observe a record number of neutrinos. It is completely filled with 20,000 tons of liquid scintillator, a special liquid that emits light when traversed by a charged particle.
“This is a key moment for the JUNO collaboration and for the JUNO group at ULB, said Barbara Clerbaux, professor, lead FNRS IISN promoter, and principal investigator of the JUNO group at ULB. It’s rewarding to see our combined expertise come together in such a remarkable detector, which will serve the global physics community for decades. This large detector is designed to collect an unprecedented sample of neutrino interactions from various sources. Neutrinos—neutral, extremely light, and very weakly interacting particles—remain among the least understood in physics. JUNO will carry out crucial measurements to improve our understanding of their properties and answer fundamental questions in particle and astroparticle physics. Exciting discoveries lie ahead.”
La Belgique est membre de JUNO depuis 2015 via une équipe de l'ULB. Le FNRS a largement contribué au financement du détecteur en soutenant les chercheurs et chercheuses qui y travaillent. L’équipe de recherche belge, basée à l’IIHE (Institut Interuniversitaire des Hautes Énergies ULB-VUB), a pris la responsabilité du développement des cartes de traitement (Backend Cards, BEC) du système de lecture électronique, couvrant la conception, les tests, la production et l’installation. Il s’agit d’un élément essentiel, qui participe au système de déclenchement de l'expérience. Celui-ci permet d'identifier et d'enregistrer les signaux les plus intéressants.
Belgium has been a JUNO member since 2015 through a team at ULB. The FNRS has significantly contributed to funding the detector by supporting the researchers involved. The Belgian research team, based at the IIHE (Interuniversity Institute for High Energies ULB-VUB), was responsible for developing the Backend Cards (BEC) of the electronic readout system—covering design, testing, production, and installation. This is a critical component that contributes to the experiment’s trigger system, which identifies and records the most interesting signals.
The Belgian team is also actively involved in preparing the physics analyses, commissioning and calibrating the detector, and analyzing the very first data. Marta Colomer Molla, FNRS Postdoctoral researcher, and Amina Kathun (postdoctoral researcher), along with students, play a key role in optimizing the detection of atmospheric neutrinos in JUNO. Marta Colomer is notably responsible for coordinating the atmospheric neutrino analysis group. The group is also involved in detecting neutrinos from potential core-collapse supernovae and contributes to an international alert network. Finally, the Belgian team is participating in the calibration of the detector using reference signals from natural radioactivity and external sources placed inside the detector.
“It’s extraordinary to now see the detector operational and recording high-quality data! It was a thrilling moment to observe the first cosmic muons passing through the detector. We can now monitor this background noise and keep it at a stable rate. We also successfully recorded the first neutrinos from the nuclear reactors, with their characteristic prompt and delayed signals, which will be essential for studying neutrino oscillation phenomena”, explained Marta Colomer.
“JUNO is not just a reactor neutrino detector, but a true neutrino observatory that could revolutionize both fundamental physics and our understanding of the Universe and the Earth”, concluded Barbara Clerbaux.
Stéphanie Tuetey (article based on the ULB press release)
Juno construction 2024 (c) JUNO Collaboration
The JUNO detector seen from outside (c) JUNO Collaboration
The central acrylic sphere and PMTs (c) JUNO Collaboration
