News & Analysis Physics World  October 2016
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Nobel winner criticizes China collider

Chen Ning Yang, who shared the 1957 Nobel Prize for Physics, has openly questioned whether China should build a Higgs factory. But others disagree, as Ling Xin reports

The Chinese-born physics Nobel laureate Chen Ning Yang has publicly questioned China’s plans to build what would be the world’s largest particle collider – the Circular Electron Positron Collider (CEPC). In an article published in the Intellectual – an online platform dedicated to communicating science and “evoking independent thinking” among Chinese readers – Yang estimates that the cost of the CEPC would be at least $20bn, possibly resulting in “a bottomless pit” for funds. Yang, who shared the 1957 Nobel Prize for Physics with Tsung-Dao Lee for their work on parity violation, draws parallels with the Superconducting Super Collider (SSC) project in Texas, US, which was cancelled in 1993 even though construction had started and $2bn had already been spent.

Proposed in 2012 as a “Higgs factory” twice the size of CERN’s Large Hadron Collider (LHC), the CEPC is expected to start construction in 2022. With a 53.6 km circumference, it would be a successor to the Beijing Electron Positron Collider (BEPC) at the Institute of High Energy Physics (IHEP) in Beijing, which is expected to shut in 2020. The CEPC would operate at 240 GeV generating copious amounts of Higgs bosons so that its mass can be precisely measured. Physicists hope to later upgrade it to form a Super Proton–Proton Collider, operating in the range of 70–100 TeV.

A preliminary conceptual design for the CEPC has already been published but an initial research proposal on the CEPC from IHEP was rejected in August by the National Development and Reform Commission. The project has, however, won support from the Chinese Academy of Sciences and the Chinese Ministry of Science and Technology. If the CEPC finally gets the nod from the Chinese government, it will most likely be built 300 km east of Beijing at the port city of Qinhuangdao.

A collider with benefits

Controversy has reigned over the project since it was first proposed in 2012, mainly due to its price tag. In Yang’s article, which appears under the headline “A super collider is not for today’s China”, the 93-year-old laureate, who now lives in China, claims that such a luxurious machine as the CEPC is “inappropriate” for a developing country that is still struggling with “more acute issues like economic development and environment protection”. Yang also expresses concern that the science performed on the CEPC is just “guess” work, ill-grounded and without guaranteed results. “I am not against the future of high-energy physics, but the timing is really bad for China to build such a super collider,” he says. “Even if they see something with the machine, it’s not going to benefit the life of Chinese people any sooner.”

Yet within 24 hours of Yang’s article appearing online, IHEP director-general Yifang Wang, who is leading the CEPC project, refuted Yang’s arguments in another article in the Intellectual entitled “A super collider is for today’s China”. Based on “solid calculations”, Wang claims that the actual budget for the CEPC is around $6bn, a third of which would be contributed by other countries. “The SSC was the victim of political struggles and bad management,” he says. “With experiences from the BEPC, we are confident that the planning of the CEPC is mature and the implementation will go smoothly.” Wang reiterates the importance of doing research on the Higgs and adds that he is convinced that the building of such a collider would drive major technical developments in China from precision machinery to data acquisition and processing. “I respect Professor Yang, but I respect science and rationality more,” Wang writes.

I respect Professor Yang, but I respect science and rationality more

A researcher from IHEP, who is not directly involved in the project and wanted to remain anonymous, told Physics World that “everyone knows” that Yang is against the CEPC. “It makes no sense to compare the CEPC with the SSC,” he says. “Besides, the money for the CEPC over China’s entire research expenditure is much smaller than what the BEPC had cost China in the 1980s.” While early-career physicists have expressed their desire for China to build a collider, Yang is by no means the only one who is vetoing it. “Opinions are polarized even within the high-energy community, and some older people never hide their objections”, says the IHEP researcher, describing it as a war between “the new and the conservative”.

This kind of public argument is rare in China, but Xiaoming Li, editor of the Intellectual, see the dispute as “a big step forward towards more open and outspoken discussions on science and social issues”. He believes it “helps to raise public awareness and understanding of the science itself, and at the same time cultivates a free expression and debate spirit”.

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