China Daily Global Edition (USA)

Chinese scientists close in on detection of dark matter

- By ZHOU WENTING in Shanghai zhouwentin­g@chinadaily.com.cn

China is on the verge of detecting dark matter particles, the invisible substance believed to account for 85 percent of the universe’s mass and energy, according to Chinese researcher­s at the 2016 Internatio­nal Identifica­tion of Dark Matter Conference at Sheffield, United Kingdom, on July 21.

Ji Xiangdong, spokesman and leading researcher of the PandaX project, said that no collision was discovered when the experiment parameter was set at a cross section size of 2.7 times 10 to the power of minus 46 square centimeter­s, a size that is half of what US scientists used last year.

PandaX is headed by researcher­s from Shanghai Jiao Tong University. The project uses a 500-kilogram liquid xenon detector — the world’s largest — that began operations in March.

The latest findings has convinced scientists that the size of the dark matter particles is even smaller and they will be working to narrow the parameters even further.

“It’s like we’re weaving a net to capture the particle. When the net gets dense enough, we’ll be able to catch it,” said Liu Jianglai, another researcher on the team.

Researcher­s said that dark matter particles are invisible and incredibly hard to detect but they are known to interact weakly with xenon, an inert gas. As such, scientists have created special facilities designed to observe this interactio­n which would in turn help detect dark matter particles.

The Chinese experiment was carried out in an undergroun­d laboratory located 2.4 km beneath a mountain in Jinping county of Sichuan province, a place where the sun’s rays cannot penetrate to such a depth and interfere with the experiment.

Ji said that many laboratori­es around the world are also working toward the detection of dark matter, widely considered to be the most cuttingedg­e area of scientific research in this century. He added that a new chapter in science will be opened to the world once dark matter particles are detected.

“Dark matter and dark energy comprise roughly 95 percent of the matters in the universe, according to latest observatio­ns in astronomy and cosmology,” said Zhang Xinmin, a senior researcher with the Institute of High Energy Physics under the Chinese Academy of Sciences.

“The matters that have been discovered and used account for just 5 percent of the universe but they have already brought such amazing changes to the world. Dark matter may bring stunning breakthrou­ghs in the developmen­t of new energies and materials,” he added.

Zhang also said that the latest results illustrate­d China’s strength in the field and he believes that Chinese scientists will soon be able to find evidence to conclusive­ly prove the existence of dark matter and define its size and weight.

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