JUNO's first physics result was published as a cover article in Nature on June 10. Through the analysis of valid data collected over 59 days from August 26 to November 2, 2025, the JUNO Collaboration led by the Institute of High Energy Physics of the Chinese Academy of Sciences made the high-precision measurement of the two key oscillation parameters, reducing the associated uncertainties by a factor of 1.6 compared to the combined experimental results in the past decades.

Neutrinos have no electrical charge and very little mass, with very little interaction with matter. A typical neutrino can pass through normal matter unimpeded, making the detection of neutrinos very difficult. Among all elementary particles, neutrinos are the least known.

JUNO began data taking in August 2025, with the primary physics goal to determine the mass ordering of neutrinos. It is also able to measure three out of the six neutrino mixing parameters to a precision better than 1%, and conduct studies on supernova neutrinos, geo-neutrinos, solar neutrinos, atmospheric neutrinos, etc.

The reviewer gave high praise for this study: These results not only validate the detector performance and analysis methodology but also establish JUNO as a key player in the emerging precision era of neutrino oscillation physics, with direct implications for tests of the three-flavor paradigm, global oscillation fits, and future determinations of the neutrino mass ordering.

Nature published a News & Viewsarticle on this study, noting that "Understanding the behaviour of neutrinos is paramount to developing a complete description of matter and forces at the smallest scale. This first analysis builds confidence that the detector will be able to determine the mass ordering. This first result from JUNO marks the dawn of the next era of precise neutrino oscillation measurements, and will provide insights into the properties of these mysterious fundamental particles."

In April this year, Chinese Physics C published a cover article on JUNO's detector performance. Prof. Arthur McDonald, who was awarded the 2015 Nobel Prize in Physics for the discovery of solar neutrino oscillation, remarked on the article: JUNO has met its design objectives, achieving exceptional radiopurity, energy resolution, and detector stability. The experiment is fully operational and ready to pursue its ambitious physics goals, including determining the neutrino mass ordering (NMO), studying neutrino oscillation parameters, detecting neutrinos from various sources, and exploring physics beyond the Standard Model for Elementary Particles.

700 meters underground, right at the heart of JUNO, stands a central liquid‑scintillator detector with an unprecedentedly large effective mass of 20,000 tons, housed at the center of a 44‑meter‑deep water pool. A 41.1‑meter‑diameter stainless steel truss supports the 35.4‑meter acrylic sphere, the scintillator, 20,000 20‑inch photomultiplier tubes (PMTs), 25,600 3‑inch PMTs, front‑end electronics, cabling, anti‑magnetic compensation coils, and optical panels.

All PMTs operate simultaneously to capture scintillation light from neutrino interactions and convert them to electrical signals. JUNO can measure precisely the energies of neutrinos upon their interaction to determine oscillation parameters.

JUNO has been running smoothly for nine months to date. As data accumulates, numerous new results will be released sequentially starting from this summer, unlocking the mysteries of neutrinos.

Figure 1: The cover of Nature (Image by JUNO Collaboration)

Figure 2: The cover of Chinese Physics C (Image by JUNO Collaboration)

Figure 3: The first physics result of JUNO (Image by JUNO Collaboration)