World's largest transparent spherical neutrino detector starts operation

The world's largest transparent spherical detector on Tuesday completed the filling of 20,000 tonnes of liquid scintillator, officially starting operation and data collection.

After over a decade of preparation and construction, the Jiangmen Underground Neutrino Observatory (JUNO) has become the world's first operational ultra-large-scale and ultra-high-precision neutrino-specific scientific facility.

The initial data obtained during its trial operation showed that the key performance indicators of JUNO have fully met or exceeded design expectations.

The core of JUNO is a liquid scintillator detector immersed in a 44-meter-deep cylindrical pool in the underground hall buried deep in a granite layer of a hill in Jiangmen City, south China's Guangdong Province. The detector is supported by a stainless steel mesh shell with a diameter of 41.1 meters, which holds an acrylic sphere with a diameter of 35.4 meters that can be filled with 20,000 tonnes of liquid scintillator.

The detector is equipped with 20,000 photomultiplier tubes of 20 inches and 25,000 photomultiplier tubes of three inches, as well as cables, magnetic shielding coils, light baffles and other components.

Neutrinos, the smallest and lightest among the 12 elementary particles that make up the material world, are electrically neutral and travel at a speed close to light. Since the Big Bang, they have permeated the entire universe and generated various phenomena, such as nuclear reactions inside stars, supernova explosions, the operation of nuclear reactors, and the radioactive decay of substances in rocks.

Since neutrinos rarely interact with ordinary matter, they can easily zip through our bodies, buildings or the entire Earth without being felt, hence earning the nickname "ghost particles." Due to their elusive nature, neutrinos are the least understood fundamental particles, requiring massive detectors to capture their faintest traces.

JUNO aims to measure the neutrino mass hierarchy as its primary scientific goal and will conduct several other cutting-edge research projects. The JUNO team comprises more than 700 members from 17 countries and regions.

World's largest transparent spherical neutrino detector starts operation

World's largest transparent spherical neutrino detector starts operation

World's largest transparent spherical neutrino detector starts operation

World's largest transparent spherical neutrino detector starts operation

Chinese Premier Li Qiang on Thursday presided over a State Council executive meeting that studied work on building a unified national market and reviewed and approved a plan for the development of a modern emergency response system during the 15th Five-Year Plan period (2026-2030).

Noting that building a unified national market is essential to advancing high-quality development, the meeting called for deepening institutional frameworks in areas such as property rights protection, market access, fair competition, social credit and market exit mechanisms.

The meeting also urged efforts to advance high-standard connectivity of market infrastructure to facilitate smooth economic circulation and effectively reduce logistics costs across society.

Emergency management is critical to protecting people's lives and property, the meeting said. It called for accelerating the development of a modern emergency response system, deepening reform and innovation in emergency management, and improving coordinated response mechanisms.

Efforts should be made to strengthen risk prevention at the source, enhance monitoring, forecasting and early warning, and accelerate a shift in governance toward proactive prevention, according to the meeting.

A draft revision of the Law on the People's Bank of China was also discussed and approved in principle at the meeting, which decided to submit the draft to the Standing Committee of the National People's Congress for deliberation.

Chinese premier chairs State Council executive meeting