Daya Bay experiment

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Daya Bay Antineutrino Detector
The two reactor blocks of the Daya Wan nuclear power plant, two of six reactor cores that are used as neutrino sources for the Daya Bay experiment

The Daya Bay experiment is a neutrino experiment in the People's Republic of China to measure the last as yet unknown neutrino mixing angle θ 13 . The experiment is located about 52 km north of Hong Kong and 45 km east of downtown Shenzhen and is run by a multinational research group made up of scientists from the People's Republic, Taiwan , the United States , the Czech Republic and Russia . It is considered the most important international research project in China and the first major collaboration between China and the United States in basic research .

The total of three neutrino mixing angles describe how often transitions between the different types of neutrinos can be expected. Two of these mixing angles have been known for a long time, the last still unknown value θ 13 is being searched for in various experiments all over the world. It concerns the conversion of the electron neutrino into other types. The angle is determined indirectly by measuring a deficit of detected antineutrinos that are produced in the six reactor blocks of the nearby Daya Wan and Ling'ao nuclear power plants .

To this end, eight neutrino detectors will be set up, four of them about 400 meters from the reactors, the other four at a distance of about 1700 meters. A comparison of the neutrino rates measured in the detectors near and far from the reactors suggests a deficit, which in turn suggests a conversion into undetectable types of neutrinos. This approach is similar to that of the competing experiments Double Chooz in France and RENO in Korea.

On March 8, 2012, the Daya Bay group published a paper in which a non-zero mixing angle θ 13 was determined with a significance of 5.2 standard deviations :

The measurement is consistent with earlier, but not yet statistically significant results of T2K , MINOS and Double-Chooz and is often rated as the most important result in the history of Chinese physics. The fact that the mixing angle θ 13 is not zero, but even comparatively large, gives additional impulses for further research into CP violations , which can now be measured in principle with neutrino oscillations. CP violations may explain why the universe is made up almost entirely of matter rather than antimatter .

For 2016, the Daya-Bay team with the lead scientists Kam-Biu Luk and Yifang Wang received the Breakthrough Prize in Fundamental Physics along with other neutrino experiments .

Web links

Individual evidence

  1. ^ Catching Neutrinos in China , in Symmetry Magazine October 2006, accessed September 26, 2012
  2. Daya Bay Collaboration: Observation of electron-antineutrino disappearance at Daya Bay . In: Physical Review Letters . 108, No. 17, 2012, p. 171803. arxiv : 1203.1669 . doi : 10.1103 / PhysRevLett.108.171803 .
  3. ^ Adrian Cho: Key Neutrino Measurement Signals China's Rise . In: Science . 335, No. 6074, 2012, p. 1287. doi : 10.1126 / science.335.6074.1287 .
  4. ^ Neutrino greetings from Hong Kong , in Die Zeit of April 3, 2012, accessed on September 26, 2012
  5. ^ Eugenie Samuel Reich: Neutrino oscillations measured with record precision . NatureNews. March 8, 2012. doi : 10.1038 / nature.2012.10202 . Retrieved May 12, 2012.