largest, underground laboratory, was launched in China.2 The facility plans to take advantage of infrastructure being developed by the Ertan Hydropower Development Company (EHDC) in the course of installing a series of 21 hydroelectric power stations on the Yalong River in central China. A system of tunnels 17.5 km long will cut a big U-turn in the river under the 4,193-m-tall JinPing mountain. This system will have a flat area available for development as an underground laboratory that provides at its greatest depths a 2,500 m vertical rock overburden and more than 1,500 m vertical overburden in 70 percent of the directions. The access will be horizontal, from both sides.
Two small experimental halls 5 × 5 × 30 m3 are under construction; their relative size is shown in Figure 2.2. The final size of the laboratory has not been publicly disclosed, although it has been reported that the laboratory will be designed as an international facility, open to the world community. Ventilation, laboratory-grade power supply, and germanium detectors with their shielding will be installed. The muon flux (expected to be very low, on the order of 20 per m2 per year), the neutron flux, and radon concentration in the air will be measured shortly. A working group including scientists and engineers from Chinese institutions and universities as well as EHDC has been established to develop plans for this facility.
2 Qian, Yue. 2010. Status and prospects of China JinPing deep underground laboratory (CJPL) and China dark matter experiment (CDEX). Presentation at the TeV Particle Astrophysics 2010 Conference, Paris, France.