China, U.S. to launch joint neutrino experiment

Chinese and U.S. physicists are to jointly conduct the world's largest neutrino experiment at the Daya Bay Nuclear Plant in south China.

The experiment, costing roughly 400 million yuan (50 million U.S. dollars), is designed to test the mixing angle of neutrino 13, which is a vital measurement in the most advanced particle physics.

Scientists from the Chinese Academy of Sciences (CAS) and the U.S.-based Brookhaven National Laboratory and the Lawrence Berkeley National Laboratory will participate in the underground experiment.

Chen Hesheng, a CAS member who heads the CAS Institute of High Energy Physics, said Thursday, "We're going to complete a tunnel connecting three different underground labs harboring neutrino detectors by 2008.

"We'll install all the three detectors by 2009 and get scientific data from 2010 on," said Chen, who coordinates the international research collaboration.

The CAS will invest 150 million yuan in building infrastructure facilities and half of the detectors, while the Americans are going to finance the remaining detectors with about 30 million U.S. dollars.

An uncharged elementary particle, the neutrino is vitally important to the study of particle physics as well as explore origin and evolution of the universe. A precise scientific description of the neutrino is believed to be the key to better understanding the formation of the solar system.

In studying neutrino physics, scientists designed solar, atmospheric, nuclear reactor and accelerator experiments.

"The reactor neutrino experiment is most likely to help us make breakthroughs," Chen said

Nuclear reactors are ideal sources for disseminating neutrinos and detectors could be deployed in places near to sources of radioactivity.

"We are able to get perfect data from detectors around nuclear plants," Chen said.

Scientists were planning similar experiments at commercial nuclear sites in other parts of the world, but Daya Bay was the best site for conducting such neutrino experiments, Chen claimed.

By 2010 when the Daya Bay Nuclear Plant and the adjacent Ling'ao Nuclear Plant were upgraded, the electricity-generating compound would be ranked the second largest in the world. The hilly landscape at the Daya Bay area made the site perfect for neutrino experiments.

"With deliberate analysis and careful calculation after several site visits, we're confident that ours will be the most precise experiment in the world."

Scientists are expected to dig deep into the mountains near the Daya Bay, installing three neutrino detectors, each weighing 100 tons, inside the underground laboratories. The nearest detector would be 260 meters from the nuclear plant and the farthest 2,000 meters. With those advantages, Chen said, the risk of systematic error would be controlled at the lowest possible rate.

China's Ministry of Science and Technology, the CAS, and the National Natural Science Foundation of China -- the three biggest funding sources for natural scientific research in China -- have all pledged further funding for the ambitious experiment.

"Chinese scientists need to be active in keeping abreast of the leading research," Chen said.

Source: Xinhua

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