China Tests Deep-Sea Device to Track Ghost Particles in the South China Sea

Chinese researchers have achieved a significant milestone in the quest to detect elusive subatomic particles known as neutrinos. The team from Shanghai Jiao Tong University's Tsung-Dao Lee Institute recently conducted a successful sea trial of the Subsea Precision Instrument Deployer with Elastic Releasing (Spider), a submersible device designed to deploy sensor arrays deep beneath the ocean's surface.

The Spider: A Precision Deployment System

During the trial, the Spider uncoiled a 700-meter string of 20 sensor balls at a depth of approximately 1,700 meters. Each sensor ball was positioned at precise angles to detect neutrinos resulting from cosmic or atmospheric nuclear reactions. This deployment is a precursor to the construction of one of the world's largest neutrino observatories, planned for the South China Sea.

The Spider's design draws inspiration from the controlled release mechanisms of spiders, ensuring that each sensor is deployed with high precision. This capability is crucial for the planned observatory, which aims to deploy about 1,000 detector strings arranged in a circular pattern and anchored 3,500 meters below the ocean's surface.

TRIDENT: China's Ambitious Neutrino Telescope

The Tropical Deep-sea Neutrino Telescope (TRIDENT), also known as Hailing, is an ambitious project by China to build the world's largest underwater neutrino detector deep in the Pacific Ocean. Set to be completed by 2030, TRIDENT aims to detect high-energy astrophysical neutrinos by capturing rare flashes of light caused by these particles interacting with water molecules. With over 24,000 optical sensors, TRIDENT will offer unprecedented sensitivity and a comprehensive all-sky observation capability.

TRIDENT's design includes hybrid digital optical modules and advanced calibration systems, such as real-time optical calibration using camera systems. These innovations are expected to enhance the telescope's angular resolution and energy measurement capabilities.

Complementary Efforts: HUNT and JUNO

In addition to TRIDENT, China is developing the High-energy Underwater Neutrino Telescope (HUNT), another large-scale neutrino observatory planned for the South China Sea. With a projected detection volume of about 30 cubic kilometers, HUNT is poised to become the largest neutrino telescope ever built, complementing TRIDENT's capabilities.

On land, the Jiangmen Underground Neutrino Observatory (JUNO) is under construction in Guangdong province. JUNO aims to determine the neutrino mass hierarchy and perform precision measurements of neutrino properties, contributing to a comprehensive understanding of neutrino physics.

Global Context and Future Prospects

China's efforts in neutrino detection place it alongside other international initiatives. For instance, the IceCube Neutrino Observatory at the South Pole and the Baikal-GVD in Lake Baikal are significant contributors to the field. These observatories employ various detection methods, including the use of photomultiplier tubes to detect Cherenkov radiation from neutrino interactions.

The successful deployment of the Spider and the advancement of projects like TRIDENT and HUNT underscore China's commitment to exploring the fundamental particles that permeate the universe. These endeavors not only aim to detect neutrinos but also aspire to unravel the origins of cosmic rays and other high-energy phenomena, potentially leading to groundbreaking discoveries in particle physics and astrophysics.