Juno - China's HK$2 billion ambition to catch the 'phantom particle'

A vast laboratory being built in Guangdong province to study elusive particles that pervade the universe could help establish China as global leader in this branch of physics research, scientists say.

The Jiangmen Underground Neutrino Observatory, or Juno, aims to measure the relative weight of neutrinos, sub-atomic particles that until less than two decades ago were considered to have no mass. It has been one of the missing pieces of the puzzle to understand the age and shape of the universe.

“This is one of the key questions for the next decade,” said Karsten Heeger, professor of physics at Yale University in New Haven, Connecticut. “The question is who can get there first.”

Heeger said similar research projects were in various stages of planning in the US, Europe, India and even the South Pole, but the Chinese project was leading the race.

“Several countries have completed plans, but China is starting to build theirs,” he said. “Juno is advancing very fast.”

Construction of the HK$2 billion project, about 150 kilometres northwest of Hong Kong, is set to begin by the end of the year, said Wang Yifang, a Chinese Academy of Sciences (CAS) physicist who heads the Juno project. Scientists from six other countries have expressed interest in co-operating in the venture.

Surveys of the site were completed earlier this year, said staff member at the Institute of High Energy Physics at CAS in Beijing. By 2017, Wang’s team plans to complete the 80-metre tall experimental facility –  some 700 metres underground – near Kaiping.

Experiments to measure the particles are expected to start in about 2020 and run for two decades. The detector will measure neutrinos sourced from two nearby nuclear power plants that have yet to be built.

“It is a very ambitious experiment,” Heeger said. “It still requires significant advances in the way we measure neutrinos.”

Though ubiquitous, neutrinos are so tiny they can pass through all the atoms of the earth’s mass with colliding with other matter. 

Immortalised by the American poet John Updike’s poem Cosmic Gall for their elusiveness (“The earth is just a silly ball / To them, through which they simply pass), neutrinos –  dubbed “phantom particles” – have become a new hot topic in popular science.

The magazine Physics World declared the detection of cosmic neutrinos at an observatory at the South Pole to be the physics breakthrough of the year 2013.

Scientists had to drill holes 2.5 kilometres deep into Antarctic ice and used a massive ice cube measuring one cubic kilometre as a detector for the elusive particle.

“Drum roll, please. The neutrino is ready to take centre stage,” Ray Jayawardhana, a professor of astronomy and astrophysics at the University of Toronto, wrote in the New York Times in December. “It’s Neutrino time.”

For scientists, establishing the mass of the elusive particles may hold the key to understanding to what happened after the so-called Big Bang some 14 billion years ago, which led to the creation of matter and anti-matter. “The big question is why there is matter and why the anti-matter disappeared,” said Heeger. “[Answering that] would be a big deal.”

China entered neutrino physics in a joint experiment with international and Hong Kong scientists at Daya Bay, Shenzhen, in 2003. The project led to first results in 2012.

Hopes are high that the Juno project could build on the previous success, but anxieties persist. “It’s never been done before,” said Wang.