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World's Biggest Particle Physics Lab May Idle All Accelerators in 2012
26 July 2010 3:30 am
PARIS—Particle physicists and science fans everywhere knew that the European particle physics laboratory, CERN, near Geneva, Switzerland, would shut down the Large Hadron Collider (LHC), the world's largest atom smasher, for all of 2012 for repairs. Many expected that the shutdown would stretch to more than a year, which CERN officials confirmed today. But most probably did not expect CERN to idle all its other accelerators at the same time, shutting down a variety of smaller projects and forcing hundreds of scientists not working on the LHC to take an unanticipated break in data taking, as lab officials are considering. The longer shutdown could be a chance for U.S. scientists working on the Tevatron at Fermilab in Batavia, Illinois, if researchers there can persuade lab management to keep the machine going instead of shutting it down in 2011 as currently planned.
Most crucially, the CERN brass say the shutdown will allow them to redo thousands of unreliable solder connections between the accelerator's massive superconducting magnets and make other modifications. Today, Stephen Myers, CERN's director for accelerators and technology, presented a schedule to the 1000 physicists gathered here for the annual International Conference on High Energy Physics that the shutdown that shows the downtime stretching 15 months. Even with all that time, CERN will need all the workers it can get, which is why they may shut down all eight of the lab's accelerators. "Our plan is to stop all of the accelerators at CERN and redeploy manpower," Myers says. The final decision on that proposal must be made by the CERN Council, which comprises representatives from the lab's 20 member nations.
That will most likely come as hard news to hundreds of physicists working on smaller experiments fed by those other accelerators, such as the 200 working on the OPERA neutrino experiment in the underground Gran Sasso National Laboratory in Italy. For a year, CERN will stop sending a beam of neutrinos to Gran Sasso, turn off the flow of antiprotons for antihydrogen experiments, and cease the production of radioactive isotopes for nuclear science experiments. But that's a price CERN is willing to pay to get the LHC running at full energy and intensity, Myers says: "Our priority is the LHC." He notes that CERN also stopped all of its accelerators in 2005 to focus on problems in the LHC's construction.
The LHC cannot run at full energy until the problematic connections are reworked.
In September 2008, just 9 days after physicists first circulated protons through the 27-kilometer-long subterranean accelerator, the LHC suffered a catastrophic failure when one of those connections melted. After 14 months of repairs, CERN officials decided to limit the accelerator to half-energy to protect the connections and to shut down to repair them as soon as the LHC had produced a sizable data set, which should be by the end of next year. The 15 month downtime will also enable workers to make an unrelated modification. They will install new "collimators"—devices to catch stray protons and help keep the beam from hitting the accelerator itself—which should allow accelerator operators to greatly increase the collision rate, Myers explains.
It may be a tad frustrating for researchers working on LHC to take a longer-than-expected break, as the accelerator and its experiments are currently running superbly. As many talks at a physics meeting here have demonstrated, scientists working on those experiments are still just proving their detectors and "rediscovering" the known particles. But in many cases, scientists here have said, they've completed in just 3 months tests that could have taken a year and are on the verge of starting the search for new physics. "If you look at the plots of what they see in data and what they predict in their simulations, the agreement is amazing," says Melvyn Shochet, an experimenter at the University of Chicago in Illinois. So just as things are finally going really well, a longer shutdown looms on the horizon.
*This story has been modified to reflect that the proposal to stop all accelerators awaits final approval and that CERN did not previously specify the length of the LHC shutdown.