Particle physicists are now hot on the trail of a cold linear collider. At a meeting in Beijing on 21 August, scientists from the International Committee for Future Accelerators (ICFA) announced that the next flagship linear collider--if it's ever built--will use cold, superconducting technology rather than warm, traditional conductors. This ends a years-old debate about the workings of the linear collider's guts and allows engineers and scientists to prepare a formal design of the multibillion-dollar instrument.
A linear collider is the next logical step in particle physicists' attempts to understand the fundamental forces and particles in the universe. In 2007 or 2008, a monstrous atom smasher, the Large Hadron Collider (LHC), will begin to search for new particles--and the majority of particle physicists have high hopes that the LHC will discover important exotica such as the Higgs boson and "supersymmetric partners." But the LHC won't have the finesse to analyze those discoveries in detail. Hence the desire to build a linear collider, which can be used to figure out the properties of the exotic new particles with great precision.
Particle physicists agreed in 2001 to pursue a linear collider (Science, 27 July 2001, p. 582), but a debate ensued over the best method for accelerating the electrons and antielectrons to smashing speed. Some scientists favored a traditional "warm" approach in which copper cavities pump an extremely large amount of energy into the accelerating particles in a relatively small space. Others championed superconducting niobium cavities that would accelerate the electrons and antielectrons at a more leisurely pace but with greater efficiency.
Most scientists agreed that either technology would have done the job just fine. Nevertheless, a panel of ICFA decided to recommend the cold technology. "It was not an easy task," says Paul Grannis, a particle physicist at the State University of New York, Stony Brook, and member of the ICFA panel. Grannis says that deciding factors included the cold technology's lower sensitivity to ground motion and other disturbances, as well as the leg up that the technology will get thanks to a planned German accelerator that uses a similar design.
Now that the technology for the accelerator has been chosen, ICFA will soon pick a team that will come up with a conceptual design for the machine, a task that should take 2 years or so. "It's a very important point," says Jonathan Dorfan, director of the Stanford Linear Accelerator Center and a member of ICFA. "We will all come together now, enthusiastically, to come to a design."
ICFA site at Fermilab