Bird vs. Big Bang Machine
Posted: Friday, November 13, 2009 7:35 PM by Alan Boyle
CERN / CMS Collaboration |
A computer-generated graphic shows particles flying through the Large Hadron Collider's Compact Muon Solenoid detector during a "splash event" on Nov. 7.
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The world's biggest and most expensive particle-smasher, the Large Hadron Collider, is all warmed up (and cooled down) for a fresh start after a few snags, including an unfortunate incident that involved a bird and a baguette.
Fourteen months ago, the LHC began operating in the middle of a media spotlight fit for a rock star - but broke down after only nine days. A faulty electrical interconnection between the underground collider ring's high-powered magnets, coupled with a helium leak, caused significant damage to the ring - and the LHC has been closed for repairs ever since.
Those repairs included the installation of a magnet protection system that would automatically shut down the collider if anything similar should happen again. The LHC is now undergoing its final checkouts, including a test last weekend that involved sending beams of protons halfway around the ring.
The collider's handlers at the CERN particle-physics center, on the French-Swiss border, say the test provided "valuable data" for synchronizing the equipment. (It also provided a valuable excuse for bubbly toasts.)
If all continues to go well, CERN spokesman James Gillies told me that proton beams should start going all the way around the ring again "within the next 10 days or so." That squares with a report in the CERN Bulletin that beams will be circulating in both pipes "just over one week from now."
Bigger milestones lie ahead, Gillies said. The first-ever proton collisions are expected to take place a week or two after the beam restart, at relatively low energies of 450 billion electron volts per beam. Those energies will be gradually ramped up to as much as 1.2 trillion electron volts (TeV) by Christmas, Gillies said. That would be a new record for high-energy particle collisions, exceeding the mark set by Fermilab's Tevatron.
The LHC's science program would begin in earnest after the holidays, at energies of 3.5 TeV. "The big event for us is getting the physics program going in January," Gillies told me. It might take another year to work up to the LHC's top energy of 7 TeV per beam.
Why such a gradual ramp-up? Gillies said the magnet protection system has to be commissioned at progressively higher levels to make sure there won't be any nasty surprises like last year's blow-up.
The LHC has certainly had its share of ups and downs over the past year. "We've learned a lot," Gillies said.
The bird and the baguette
The latest - and probably the silliest - setback came just last week, when a short circuit shut down a substation that supplied power to part of the LHC's cryogenic cooling system. The outage caused two sectors of the collider ring to warm up to a few degrees above its required operating temperature of 456 degrees below zero Fahrenheit (1.9 Kelvin).
"When people went to investigate the cause, they found feathers and a piece of bread," Gillies said. "It's a bit of a Sherlock Holmes-y thing."
Sleuths surmised that the short occurred when a bird dropped the bread onto the open-air substation. And thus was a legend born, about the baguette-wielding bird that brought down the world's mightiest machine.
Gillies downplayed the flap, saying that the event wasn't as serious or as strange as some have made it out to be. "I understand this kind of thing is common at power stations around the world," he told me. In the CERN bulletin, he said the outage caused no delay in LHC preparations. "Had we been running, we'd have lost a day or two's worth of beam time, which is nothing unusual when operating a frontier research machine like the LHC," he wrote.
"The moral of this story is that CERN and particle physics are in the spotlight like never before," Gillies continued. "The great adventure that is the LHC has caught the public's imagination, and there's a great thirst for information about what we’re doing. Headlines about birds and baguettes may be uncomfortable to live with, but it’s always worth remembering that this kind of attention is ultimately for the good. Soon, the headlines should be turning from birds to b-quarks, and from baguettes to bosons. It’s a day we’re all looking forward to."
From birds to black holes
Assuming that the birds leave the LHC alone, scientists will soon be using the collider to unravel mysteries ranging from the nature of dark matter to the possible existence of "the God particle" and supersymmetric particles, extra dimensions and microscopic black holes.
Oops, did I say "black holes"? Some critics still worry that the black holes created by the LHC could lead to a globe-gobbling catastrophe. Such worries have been repeatedly knocked down, however. Just this week, Discovery News' Ian O'Neill cited a fresh, yet-to-be-refereed study concluding that the LHC's micro-black holes would pose zero threat to Earth.
The researchers say that tidal black holes would evaporate virtually instantly. If they zoomed through the planet, they would be flung out into space and fizzle out. And if the black holes dropped to Earth's core and stayed there, it would take billions upon billions of years for them to grow to the size of, say, a virus.
That's how the researchers see it. The way I see it, the black-hole apocalypse rates pretty low on the plausibility scale - below the asteroid apocalypse, below the robot apocalypse, even below the cheesy kind of apocalypse laid out in the movie "2012." But how do you see it? Feel free to pick your apocalypse and discuss it in the comment section below.
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