with each pair referred to as a nuclear power plant (NPP). All six cores are functionally identical pressurized water reactors, each with a maximum of 2.9 GW of thermal power. The last core started commercial operation on 7 August 2011, a week before the start-up of the Daya Bay experiment. The distance between the cores for each pair is 88 m. The Daya Bay cores are separated from the Ling Ao cores by about 1100 m, while the Ling Ao-II cores are around 500 m away from the Ling Ao cores.

![Layout of the Daya Bay experiment. The dots represent the reactor cores, labelled as D1, D2, L1 to L4. Eight antineutrino detectors, labelled as AD1 to AD8, are installed in three underground experimental halls (EH1-EH3). The bottom sub-panel shows the survival probability as a function of the effective baseline $L$. The near and far detectors locate in the shaded area. \[fig:layout\]](DYB_8ADs.pdf){width="60.00000%"}

The Daya Bay experiment consists of three underground experimental halls (EHs) connected with horizontal tunnels. The overburden for the Daya Bay near hall (EH1), the Ling Ao near hall (EH2) and the far hall (EH3) are 250, 265, and 860 equivalent meters of water, respectively. Eight antineutrino detectors 