In the search for what could be the universe’s lone undiscovered fundamental particle, the big new atom-smasher in Switzerland is widely regarded as the only game in town.
The Large Hadron Collider, built by the European group CERN, is several times as powerful as the next-biggest accelerator, the Tevatron, near Chicago. So far the Tevatron has not been able to detect the elusive particle, the so-called Higgs boson.
Still, with the Tevatron nearing the end of its scheduled lifetime, researchers at the Fermi National Accelerator Laboratory say they’re not yet out of the hunt. Fermilab is asking Congress for $100-million to keep chasing the Higgs for three more years. Scientists say the plea is more than patriotic zeal. They see real opportunity.
One reason is that the experience of Tevatron researchers—10 years searching for the Higgs—can trump the Large Hadron Collider’s technology. Quitting now, says Ian P. Shipsey, a professor of physics at Purdue University who works at Fermilab, would be like nearing the summit of a mountain and then abandoning the mission because a better-equipped team plans to try hiking up from the other side. New equipment might not outweigh the Tevatron’s huge head start, he says.
Another reason not to abandon the effort is the likelihood that discovering the Higgs won’t be clean and simple. Any claim of discovery will require replication and involve uncertainties, and the Tevatron could provide a valuable cross-check on any claims for the Large Hadron Collider, especially if it turns out that there is more than one type of Higgs particle, Fermilab researchers say. “Even if the LHC discovers the Higgs,” says Young-Kee Kim, a professor of physics at the University of Chicago who is deputy director of Fermilab, “the Tevatron could still deliver important information about it.”
Fermilab partisans are not alone in such beliefs. Jonathan R. Ellis, a professor of theoretical physics at King’s College London who has spent more than three decades at CERN, says the Tevatron “looks in a somewhat different way for the Higgs boson from what we are planning to do with the LHC.”
He argues that “it would be useful to have the Tevatron continue to operate.”
Scientists are sure the Higgs exists because a basic everyday fact can’t be explained if it doesn’t. That fact is mass. Under close examination, all basic particles appear to be just pointlike objects, lacking any actual bulk. But many particles forming our world clearly act as if they do have mass. According to the Higgs theory, this is because our universe is bathed in an invisible field, perhaps similar to magnetism or gravity, that drags particles as they move around—sort of like mud sticking to boots—giving particles the sensation of mass. The invisible field in this case is presumed to be caused by a Higgs particle, just as an invisible magnetic field is created by the movement of electrically charged particles.
The Higgs boson was named after Peter W. Higgs, a retired professor of physics at the University of Edinburgh who was among those who developed the concept in the 1960s. It came to be called “the God particle” based on the title of a 1993 book by a former Fermilab director, Leon M. Lederman, a Nobel laureate and now a professor of physics at the Illinois Institute of Technology.
Accelerators such as the Tevatron and the Large Hadron Collider try to detect the Higgs by smashing beams of particles into one another. The collision momentarily produces different particles, presumably like the Higgs. The trick is detecting them during the fractions of a second that they exist. Researchers do that with computers, which identify postcollision debris moving at the speed and direction expected of the sought-after particle.
That’s one area in which the Tevatron’s experience is useful. A decade of picking through the debris trails of millions of collisions has given experts like Mr. Shipsey the ability to separate meaningful decay patterns from experimental trash. (In addition, some physicists think the Higgs will be of a size that’s more easily detected by Tevatron instruments than by those at the Large Hadron Collider, which are designed differently.)
But the lab’s diversifying research mission has generated some internal opposition to extending the life of the Tevatron for the Higgs hunt. Marvin L. Marshak, a professor of physics at the University of Minnesota, leads a new Fermilab project to search for nearly massless particles called neutrinos. And he says he’d have more particles for his experiments if the Tevatron weren’t competing for the supply generated at Fermilab. “I would be better off,” he says, “if there weren’t a Tevatron.”
