|File photo shows the No. 3 laboratory of the Daya Bay Reactor Neutrino Experiment, which was put into operation on Dec. 24, 2011, in south China's Guangdong Province. Chinese and foreign physicists made a pivotal breakthrough in the study of neutrinos, which might explain the predominance of matter over antimatter in the universe. Based on data collected from two powerful nuclear reactors, multinational scientists have been able to confirm and measure a third type of neutrino oscillation, Wang Yifang, a co-spokesperson for the experiment and head of the Institute of High Energy Physics (IHEP) of the Chinese Academy of Sciences (CAS), said at the press conference on March 8, 2012. The findings come from the Daya Bay Reactor Neutrino Experiment, which was conducted close to the Daya Bay Nuclear Power Station in Guangdong Province. (Xinhua)
Traveling at close to the speed of light, the three basic neutrino "flavors" -- electron, muon, and tau neutrinos, as well as their corresponding antineutrinos -- mix together and oscillate. This activity, however, is extremely difficult to detect.
Two types of oscillation, solar and atmospheric neutrino oscillation, were confirmed in experiments conducted in the 1960s and 1990s, while the third type of oscillation had not been detected prior to the Daya Bay experiment.
From last December, the scientists in the Daya Bay experiment observed tens of thousands of interactions of electron antineutrinos caught by six detectors installed in the mountains adjacent to the powerful nuclear reactors, Wang said.
The data revealed for the first time the strong signal of the effect that the scientists were searching for -- a so-called "mixing angle" named theta one third, a new type for neutrino oscillation, he said.
"It is surprisingly large," Wang said. "Our precise measurement will complete the understanding of the neutrino oscillation and pave the way for the future understanding of matter-antimatter asymmetry in the universe."
Scientists believe the intense heat of the Big Bang should have forged equal amounts of matter and its "mirror image" antimatter. But as we live in a universe composed overwhelmingly of matter today, physicists have been puzzled by the apparent "disappearance" of antimatter.