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(Bloomberg) -- CERN, the European nuclear physics research organization, is contemplating the development of a particle accelerator three times larger than the Large Hadron Collider that confirmed the existence of the Higgs boson, a move intended to match growing Chinese ambitions in particle physics.
Fabiola Gianotti, CERN’s director general, said in an interview that the organization has begun design studies for a new circular super-collider that would be between 90 to 100 kilometers long. CERN’s Large Hadron Collider, currently the world’s highest energy particle accelerator, measures 27 kilometers. The collider is famous for finding the Higgs boson in 2012, considered one of the most important discoveries in particle physics in decades. The particle helps explain how the visible universe holds together.
Chinese scientists would like to build a electron-positron circular collider twice the size of the LHC, which smashes protons together. After building this initial accelerator, China would eventually expand it into an even bigger proton collider. But initial plans to start construction in 2021 suffered a setback when the Chinese government opted not to fund the collider in its 2016 five-year plan. The research team will now to need to wait until 2020 to apply again. The effort is controversial. Chinese-born physics Nobel winner Chen Ning Yang, a U.S. citizen, argued last year that China, as a still developing country, could not afford the project, which is expected to cost as much as $6 billion in its initial phase.
Gianotti, who is the first woman to head the European nuclear research agency, said she welcomed the Chinese proposals. “I think it is very good to have competition,” she said. “It is very good to have different regions of the world that are interested in fundamental physics and consider that the outstanding questions today in particle physics are worth building the next generation particle collider.” But Gianotti said it was unlikely that both CERN and the Chinese would actually complete construction of their massive projects. “I don’t think the world can afford two such colliders,” she said, adding it was important to “optimize” available scientific expertise and financial resources for the sake of advancing science.
“There is no point having two similar accelerators,” she said.
She said that while CERN has begun initial planning for its own massive super-collider, it had not yet produced cost estimates. The growing interest from China could help Gianotti make the case for its 100-kilometer ring or for alternative proposals, such as a high-energy electron and positron accelerator known as the Compact Linear Collider. Gianotti said which project CERN will pursue would be decided in a review of Europe’s particle physics strategy in 2019.
Gianotti described the relationship with China as being collaborative as well competitive. Three CERN scientists sit on the international advisory panel for China’s electron-positron accelerator. Gianotti said discussions had taken place about strengthening CERN’s work with China and that she plans to travel to China next year for further talks.
After discovering the Higgs boson, an elementary particle that the so-called Standard Model of physics postulates is fundamental to giving objects mass, the LHC underwent a two-year retrofit. CERN upgraded the electro-magnets that allow the collider to accelerate particles to velocities approaching the speed of light, as well as the cryogenic refrigerators that keeps those magnets cooled. The new machine, which has been running since April 2015, operates at energy levels about 75 percent greater than the LHC did when it found the Higgs in 2012 and it produces almost triple the number of collisions per second. Many hoped the upgrade would allow the LHC to move beyond the visible universe and find evidence of dark matter and exotic new particles that are not accounted for by the Standard Model. But so far, Gianotti said, the LHC has not found any conclusive evidence.
“The Higgs boson behaves very much like the Standard Model predicts,” she said, while cautioning that the experimental precision of the LHC is not yet high enough to exclude that Higgs is part of a broader theory beyond the Standard Model.
The LHC is due to undergo another major upgrade starting in 2024. This turbo-boosted collider is known as the High Luminosity LHC.
“At the moment, large uncertainties still exist,” Gianotti said referring to the precision of the LHC results. “We hope that with more data and the advantage of the luminosity upgrade of the LHC, which will extend the full program of the Large Hadron Collider to 2035, by that time we will reduce the uncertainty on several measurements by some large factor.” Processing all the information the High Luminosity LHC produces will pose a monumental challenge of its own. CERN scientists this week released a paper in which they forecast that by 2026 the computing capacity required for experiments run on the collider will be 50 to 100 times greater than today, with data storage needs running into many exabytes. (By way of comparison, all the words ever spoken by humans are estimated to be about 5 exabytes, according to a 2003 report from the University of California at Berkeley’s School of Information Management and Systems.)
The CERN scientist think improvements in computing technology will be able to meet only 10 to 20 percent of these needs without additional cost. So the physics agency is calling for a major research and development effort to solve the bottleneck with more efficient software coding, changes in data center infrastructure and more use of advance machine learning techniques. CERN works with partners such as Intel Corp., Oracle Corp., Huawei Technologies Co. Ltd., and Siemens AG, on many of these efforts. CERN, which has a budget of about 1 billion Swiss francs ($1.04 billion) per year, is funding this upgrade to the LHC out of its existing finances, Gianotti said. “For a researcher like me, perhaps the best reward is a surprise,” she said. “Nature is always more clever, and perhaps also more simple and more elegant, than the human brain. So it may be the all the models that mankind have developed, these are not what Nature has finally chosen.” CERN has collaboration with U.S. physicists, with American researchers running experiments at CERN's LHC and CERN scientists working on neutrino and dark matter research at the Stanford Underground Research Facility in South Dakota. Some are concerned this research could be jeopardized by an almost 20 percent funding cut for high energy physics research and nuclear research proposed by President Trump in his 2018 budget.
Gianotti said she was optimistic that this funding would be restored by the U.S. Congress before it passes a final spending bill. “I remain pretty positive things will be okay,” she said.
--With assistance from Andy Hoffman and Dylan Griffiths
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