China Jinping Underground Laboratory

China Jinping Underground Laboratory
中国锦屏地下实验室
Motto fflux
Established December 12, 2010
Field of research
 Dark matter physics
Director Cheng Jianping[1]
Faculty Zeng Zhi
Ma Hao
Li Jianming
Wu Qifan[1]
Location Sichuan, China
28°09′12″N 101°42′41″E / 28.15323°N 101.7114°E[2]Coordinates: 28°09′12″N 101°42′41″E / 28.15323°N 101.7114°E[2]
Operating agency
 Tsinghua University
"CJPL" redirects here. For the community radio station, see CJPL-FM.

The China Jinping Underground Laboratory is a deep underground laboratory in Sichuan, China. The cosmic ray rate in the laboratory is under 0.2 muons/m²/day,[3] placing the lab at a depth of 6720 m.w.e.[4]:2 and making it the best-shielded underground laboratory in the world.[5]:17 The actual depth of the laboratory is 2,400 m (7,900 ft), yet there is horizontal access so equipment may be brought in by truck.

Although the marble through which the tunnels are dug is considered "hard rock", at the great depth it presents greater geological engineering challenges[6][7]:16–27 than the even harder igneous rocks in which other deep laboratories are constructed. But marble has the advantage for radiation shielding of being low in radionuclides,[8][9] such as 40K, 226Ra, 232Th,[5]:17 and 238U.[10]:16

The laboratory is in western China, near Tibet, about 500 km (310 mi) southeast of Chengdu.[5]:3 The closest major airport is Xichang Qingshan Airport, 120 km (75 mi) away by road.[7]:5

History

The Jinping-II Dam hydroelectric power project involved excavating a number of large tunnels under Jinping mountain: four large 16.7 km (10.4 mi) headrace tunnels for water,[6]:30 two 17.5 km (10.9 mi) vehicular access tunnels,[7]:1 and one water drainage tunnel. Hearing of the excavation in August 2008,[11][12] physicists at Tsinghua University determined that it would be an excellent location for a deep underground laboratory,[13] and negotiated with the hydropower company to excavate laboratory space in the middle of the tunnels.

A formal agreement was signed on 8 May 2009,[11] and excavation was promptly started.[7]:29 The first phase CJPL-I, consisting of a 6.5×6.5×42 m (21×21×138 ft) main hall,[14]:8 plus 55 m (180 ft) of access tunnel (4,000 m³ total excavation)[7]:15 was excavated by May 2010,[15]:7 and construction completed 12 June 2010.[15]:7 A formal laboratory inauguration was held 12 December 2010.[7]:37

The laboratory is to the south of the southernmost of the seven tunnels, traffic tunnel A.

CJPL-II, a major expansion to 96,000 m³ of space[4] (120,000 m³ total excavation[16]) is underway and expected to be completed at the end of 2015. This will make CJPL one of the largest underground physics laboratories in the world, half the size of LNGS, the world's largest (180,000 m³). The design provides four experimental halls, each 12×12×150 m[14]:13 (39×39×490 ft).

CJPL facility resources[14][17]
CJPL-I CJPL-II
Overall volume 4,000 m³
140,000 ft³ 		96,000 m³
3,400,000 ft³
Laboratory area 273 m²
2,940 ft² 		7,200 m²
78,000 ft²
Electrical power 60 kVA 600 kVA
Fresh air 40 m³/hour
1,400 ft³/hour 		5,000 m³/hour
180,000 ft³/hour

Experiments

Experiments currently operating in CJPL are:

Also operating in the laboratory is a low background facility using a high purity germanium detector, for measuring very low levels of radioactivity.[1][14]:7 This is not a physics experiment itself, but tests materials intended for use in the experiments.

Both CDEX and PandaX have plans for larger (tonne-scale) versions in the CJPL-II space.

References

  1. ↑ 1.0 1.1 1.2 Zeng, Zhi (2011-03-26). Low Background Facility Setup in CJPL: A Brief Introduction (PDF). Symposium on Future Applications of Germanium Detectors in Fundamental Research. Beijing. Retrieved 2014-11-19.
  2. ↑ 2.0 2.1 Data Acquisition Project for CJPL
  3. ↑ Wu, Yu-Cheng; Hao, Xi-Qing; Yue, Qian; Li, Yuan-Jing; Cheng, Jian-Ping; Kang, Ke-Jun; Chen, Yun-Hua; Li, Jin; Li, Jian-Min; Li, Yu-Lan; Liu, Shu-Kui; Ma, Hao; Ren, Jin-Bao; Shen, Man-Bin; Wang, Ji-Min; Wu, Shi-Yong; Xue, Tao; Yi, Nan; Zeng, Xiong-Hui; Zeng, Zhi; Zhu, Zhong-Hua (August 2013). "Measurement of cosmic ray flux in the China JinPing underground laboratory". Chinese Physics C 37 (8): 086001. arXiv:1305.0899. Bibcode:2013ChPhC..37h6001W. doi:10.1088/1674-1137/37/8/086001.
  4. ↑ 4.0 4.1 Li, Jainmin; Ji, Xiangdong; Haxton, Wick; Wang, Joseph S.Y. (9 April 2014). "The second-phase development of the China JinPing underground Laboratory". arXiv:1404.2651 [physics.ins-det].
  5. ↑ 5.0 5.1 5.2 5.3 PandaX Collaboration (August 2014). "PandaX: A Liquid Xenon Dark Matter Experiment at CJPL". Science China Physics, Mechanics & Astronomy 57 (8): 1476–1494. arXiv:1405.2882. doi:10.1007/s11433-014-5521-2.
  6. ↑ 6.0 6.1 Zhang, Chunsheng; Chu, Weijiang; Liu, Ning; Zhu, Yongsheng; Hou, Jing (2011), "Laboratory tests and numerical simulations of brittle marble and squeezing schist at Jinping II hydropower station, China" (PDF), Journal of Rock Mechanics and Geotechnical Engineering 3 (1): 30–38, doi:10.3724/SP.J.1235.2011.00030
  7. ↑ 7.0 7.1 7.2 7.3 7.4 7.5 Li, Jianmin (6 September 2013). The Status and Plan of China JinPing underground Laboratory (CJPL) (PDF). 13th International Conference on Topics in Astroparticle and Underground Physics: A Town Meeting for the 2nd-phase Development of the China Jinping Underground Laboratory. Asilomar, California. Retrieved 2014-11-19.
  8. ↑ Chui, Glennda (February 2010), "World's deepest lab proposed in China", Symmetry 7 (1): 5, ISSN 1931-8367
  9. ↑ Strickland, Eliza (January 29, 2014), "Deepest Underground Dark-Matter Detector to Start Up in China", IEEE Spectrum 51 (2): 20, doi:10.1109/mspec.2014.6729364, China’s new underground lab is the deepest in the world, meaning it’s well protected from cosmic radiation; in addition, the rock around it is marble, which is particularly devoid of radioactive materials that could produce false signals. “The big advantage is that PandaX is much cheaper and doesn’t need as much shielding material,” Lorenzon says.
  10. ↑ Pocar, Andrea (8 September 2014). Searching for neutrino-less double beta decay with EXO-200 and nEXO (PDF). Neutrino Oscillation Workshop. Otranto. Retrieved 2015-01-10.
  11. ↑ 11.0 11.1 Normile, Dennis (5 June 2009), "Chinese Scientists Hope to Make Deepest, Darkest Dreams Come True", Science 324 (5932): 1246–1247, doi:10.1126/science.324_1246
  12. ↑ Feder, Toni (September 2010), China, others dig more and deeper underground labs 63 (9), pp. 25–27, doi:10.1063/1.3490493
  13. ↑ Kang, K.J.; Cheng, J.P.; Chen, Y. H.; Li, Y.J.; Shen, M. B.; Wu, S. Y.; Yue, Q. (1 July 2009). Status and Prospects of a Deep Underground Laboratory in China (PDF). Topics in Astroparticle and Underground Physics (TAUP 2009). Journal of Physics: Conference Series 203 (012028) (Rome). doi:10.1088/1742-6596/203/1/012028.
  14. ↑ 14.0 14.1 14.2 14.3 Yue, Qian (Feb 28, 2014). The status and prospect of CJPL (PDF). Dark Matter 2014. Westwood, California. Retrieved 2014-11-19.
  15. ↑ 15.0 15.1 Wong, Henry (2011-09-06). Construction and commissioning of the China Jinping underground laboratory and the CDEX-TEXONO experiment. 12th International Conference on Topics in Astroparticle and Underground Physics. Munich. Retrieved 2014-11-19.
  16. ↑ "China expands world's deepest "dark matter" lab". Xinhua. 2014-08-02. Retrieved 2014-11-19.
  17. ↑ Wang, Joseph S.Y. (12 September 2013). The Second-Phase Development of the China JinPing Underground Laboratory for Physics Rare Event Detectors and Multi-Disciplinary Sensors. 13th International Conference on Topics in Astroparticle and Underground Physics. Asilomar, California. Retrieved 2014-11-21.
  18. ↑ Qian Yue (March 24, 2011). China JinPing underground Laboratory (CJPL) and China Darkmatter Experiment (CDEX) (PDF). Symposium on Future Applications of Germanium Detectors in Fundamental Research. Beijing. Retrieved 2014-11-19.

External links