Barely a week after it became operational, several tonnes of liquid helium leaked, delaying further tests for more than a year. But it has since repaid the faith of particle physicists and last year proved the existence of the Higgs boson – the subatomic particle that gives mass to matter.
But with the Large Hadron Collider due to go out of service before 2040, there is no time to waste in planning its replacement, argued Professor Philip Burrows, senior research fellow in physics at Oxford University.
“Since the gestation time for big accelerators is a couple of decades, we need to start thinking now if we want to have a design in hand for a possible new machine to come online at Cern in the late 2030s,” he said.
Dr Rolf Heuer, the director-general of Cern, added: “We very much hope that with the LHC running at higher energy next year, we might get the first glimpse of what dark matter is. And building on that I would assume that we then can build a physics case for a future circular collider.
The new 100km Cern tunnel is one of several proposals being considered to replace the LHC, which hurls atoms against each other at virtually the speed of light.
It is by no means certain that the collider would even be in Europe, with Japan and China interested in hosting one – and scientists are also in dispute about which particles should be tested. Some experts favour colliding protons, as is done in the 27km-long LHC, citing the ability to reach far higher energies and extremes of conditions in an attempt to simulate “Big Bang”-style conditions. Others are in favour of using electrons, as they are easier to direct and the results of tests easier to interpret.
Other plans include a compact linear collider, developing new technologies for putting energy into particle beams over short distances.
The costs of creating a new collider, in a 100km tunnel, would be enormous – an estimated 10 million cubic metres of rock would need to be dug up. Cern refuses to speculate on the sums involved, but given the £6.7bn cost of the LHC, where just 1.5 million cubic metres of rock were removed, it is likely to run to tens of billions.
Scientists are due to report to Cern on what should be built in 2018. Assuming there is agreement, it would take another 15 years or so to create the new collider.
Concerns remain over the unintended consequences of cutting-edge research. Scientists and legal experts warned that plans to upgrade the world’s second most powerful particle accelerator, at Brookhaven National Laboratory in New York, risked the creation of micro-black holes and “strangelets” – a theoretical form of matter which could create a chain reaction to convert everything into “strange matter” and destroy the planet. But then some feared the same of the LHC, and we have survived so far.
http://www.independent.co.uk/news/science/beyond-cern-now-physicists-prepareto-construct-the-even-larger-hadron-collider-9139495.html
