By Ron Cowen
Efforts to begin operation of the Large Hadron Collider, set to become the world’s most powerful atom smasher, have suffered a major setback. A faulty electrical connection and helium leak in a section of the collider’s 27-kilometer-long tunnel have forced the accelerator into an early — and prolonged — winter hibernation.
CERN announced September 23 that the collider will be shut down until next spring. Repairing the section will take an estimated three to four weeks because it will require a warm-up to room temperature. By the time engineers could cool the section back down to 1.9 degrees above absolute zero, little time would remain to operate before the LHC’s scheduled winter shutdown. (Fuel costs make running the LHC during winter too expensive.)
“The time necessary for the investigation and repairs precludes a restart before CERN’s obligatory winter maintenance period, bringing the date for restart of the accelerator complex to early spring 2009,” according to a CERN press release. “LHC beams will then follow.”
The collider’s tunnel hosts several superconducting magnets. On September 19, a faulty electrical connection between two of these giant magnets in one section of the tunnel led to a major leak of helium, the LHC’s main coolant. Engineers will have to warm up the section in order to repair it.
Before this setback, CERN had intended to have the first collisions between two beams in October. These first beams would each have had an energy of 5 trillion electronvolts — five times more energetic than those any other collider has managed. On September 10, scientists successfully sent a proton beam around the entire tunnel.
The plan had been to host this first collision before shutting down the LHC in December for four months.
When the accelerator does run at full capacity, each proton beam will carry seven times more energy and have about 30 times the intensity of any beam at any other accelerator.
The most intense collisions will generate the heat, energy and densities that existed just a trillionth of a second after the Big Bang.
Physicists hope that the LHC will lead them beyond the standard model of particle physics and to signs of extra dimensions, new types of elementary particles that could account for most of the mass in the universe and, perhaps, rapidly evaporating, microscopic black holes that the accelerator may forge.
