Green particle accelerators?
THERE are many designs on the table for the next-generation super collider. All of them are billed as “Higgs factories” because, as the particle physicist Caterina Vernieri, one of the members of the international Higgs Study group, wrote: “Clearly, one of the main experimental milestones for the post-lhc [Large Hadron Collider] landscape is the study of the Higgs boson that has the potential to shed light on a number of fundamental challenges in modern physics. The Higgs boson is one of the central elements in the future of collider physics.”
At the LHC, at CERN, Higgs bosons are produced only rarely. Physicists now want Higgs factories dedicated to churning out the particles in the hope that studying them in precise detail will lead to exciting discoveries. In a recently published work in The European Physical Journal Plus, the physicists P. Janot of CERN and A. Blondel of the University of Geneva calculated the energy consumption of five proposed Higgs factories and found that there was an enormous difference in the energy consumption of these designs and hence to their carbon footprint.
They looked at CERN’S Future Circular Collider (FCC), China’s Circular Electron Positron Collider (CEPC), and three proposed linear
colliders: Japan’s Linear Collider, CERN’S Compact Linear Collider, and the US’ Cool Copper Collider (C3). The least-polluting option, the study found, was the FCC.
According to them, it would use one-sixth the energy of the most polluting alternative, the C3. “It makes sense to look at energy consumption per Higgs boson because the ability to do science is directly related to the number of Higgs bosons produced,” said Janot. Circular and linear colliders tend to have a similar annual energy consumption, but circular ones generate Higgs bosons faster and can therefore meet the same science goals in a shorter time.
According to the study, the FCC would use 3 megawatt hours of electricity per Higgs boson produced and the CEPC 4.1 MWH. Linear machines performed worse, with C3 being the least energy-efficient at 18 MWH per boson. But the calculated carbon footprints could “change dramatically” as countries expand access to renewable power, noted Wang Yifan, director of the Institute of High Energy Physics of the Chinese Academy of Sciences in Beijing. If more than 90 per cent of the electricity at CERN is sourced from carbon-free sources, the FCC’S carbon footprint would be just 1 per cent of the most polluting alternative, says the study.