Daya Bay Reactor Neutrino Experiment

There is an affiliated project in the Aberdeen Tunnel Underground Laboratory in Hong Kong.

The Aberdeen lab measures the neutrons produced by cosmic muons which may affect the Daya Bay Reactor Neutrino Experiment.

The experiment consists of eight antineutrino detectors, clustered in three locations within 1.9 km (1.2 mi) of six nuclear reactors.

Each detector consists of 20 tons of liquid scintillator (linear alkylbenzene doped with gadolinium) surrounded by photomultiplier tubes and shielding.

[1] A much larger follow-up is in development in the form of the Jiangmen Underground Neutrino Observatory (JUNO) in Kaiping,[2] which will use an acrylic sphere filled with 20,000 tons of liquid scintillator to detect reactor antineutrinos.

[3] The experiment studies neutrino oscillations and is designed to measure the mixing angle θ13 using antineutrinos produced by the reactors of the Daya Bay Nuclear Power Plant and the Ling Ao Nuclear Power Plant.

On 8 March 2012, the Daya Bay collaboration announced[4][5][6] a 5.2σ discovery of θ13 ≠ 0, with This significant result represents a new type of oscillation and is surprisingly large.

With θ13 so large, NOνA has about a 50% probability of being sensitive to the neutrino mass hierarchy.

The collaboration produced an updated analysis of their results in 2014,[8] which used the energy spectrum to improve the bounds on the mixing angle: An independent measurement was also published using events from neutrons captured on hydrogen:[9] Daya Bay has used its data to search for signals of a light sterile neutrino, resulting in exclusions of some previous unexplored mass regions.

[10] At the Moriond 2015 physics conference a new best fit for mixing angle and mass difference was presented:[11] On 21 April 2023 (published), Daya Bay's reports the following precision measurements:

in the foreseeable future and be crucial to the investigation of the mass hierarchy and CP violation in neutrino oscillation."

This unexpected disagreement between observation and predictions suggested that the Standard model of particle physics needs improvement.