Neutrino oscillation is a new experimental phenomenon in particle physics, that a neutrino could convert from one type to another at flight. In 1998, scientists discovered the atmospheric neutrino oscillation (corresponding to the mixing angle 23). Solar neutrino oscillation (corresponding to the mixing angle 12) was discovered in 2002. These two discoveries were awarded the Nobel Prize in 2015. Neutrino oscillation indicates that neutrinos have mass, which is the only experimental evidence of new physics beyond the Standard Mode of particle physics.

Searching for the third type of neutrino oscillation, corresponding to the mixing angle 13, is the essential development of neutrino studies. The magnitude of θ13, which is one of the 28 fundamental parameters of particle physics, defines the roadmap of future neutrino studies, and relates to the mystery of the missing antimatter in the Universe. An innovative experimental scheme to measure θ13 was proposed in 2003, which led to the Daya Bay Reactor Neutrino Experiment. In 2011 a world’s leading experimental facility was built. The precision of measurement and efficiency of data accumulation is the highest among peer facilities. Among the intense international competition, the Daya Bay Experiment first released a significant result in 2012: the neutrino oscillation corresponding to θ13 does exist, and its oscillation amplitude is precisely measured to be about 0.09.

The Daya Bay discovery was extensively reported by major scientific journals and media immediately after the release of the result. It was selected as one of the Breakthroughs in 2012 by Science, who commented that“if LHC researchers do not find new particles beyond those in the standard model, the neutrino physics could be the future of particle physics - as the fact that neutrinos even have mass isn’t part of the standard model. If so, the Daya Bay result may mark the moment when the field took off”. The Daya Bay International Collaboration and its leaders, together with the other four collaborations, shared the 2016 Breakthrough Prize in Fundamental Physics, “for the fundamental discovery and exploration of neutrino oscillations, revealing a new frontier beyond, and possibly far beyond, the standard model of particle physics”.

An international collaboration consists of about 270 scientists and engineers from 38 institutions from China including Hong Kong and Taiwan, USA, Russia, and Czech worked together on the experiment, where 150 of them are from 16 domestic universities or institutions.