(LHC) Large Hadron Collider Restarts, at half speed

(Image: CERN)

A technician inspects the site of a faulty electrical connection that damaged the LHC in September 2008

The world's most powerful particle smasher will restart in November at just half the energy the machine was designed to reach. But even at this level, the Large Hadron Collider has the potential to uncover exotic new physics, such as signs of hidden extra dimensions, physicists say.

CERN Lab

The LHC is a new particle accelerator at the CERN laboratory near Geneva, Switzerland, designed to answer fundamental questions, such as what gives elementary particles their mass, by colliding particles at higher energies than ever achieved in a laboratory before.

The First Attempt

The first attempt to turn on the LHC failed in September 2008 when a joint connecting a pair of superconducting wires overheated, causing an explosive release of helium used as a coolant. Scientists have been making repairs and checking the strength of other electrical connections since then to pave the way for a second start attempt.

Restart November

Now, CERN has announced that the LHC's first data collecting run, to begin in November, will collide protons at only half the energy the accelerator was designed to achieve. The run will initially smash protons together at 7 trillion electron volts (7 TeV), compared to the design goal of 14 TeV, according to a CERN statement on 6 August. (Protons in each of the two opposing beams will have 3.5 TeV of energy, producing collisions at 7 TeV.)

Even 7 TeV is much higher than physicists have ever probed in the laboratory before. The Tevatron accelerator at Fermilab in Batavia, Illinois, is the current record holder, with collisions at 2 TeV.