The Hunt for the God Particle

sci1101god_A1.gif Scientists and engineers at CERN are working around the clock to build an upgraded particle accelerator. Scheduled to go online in 2006, the device is almost certain to detect the physicists' elusive quarry. Here, an engineer dismantles Delphi, one of the four detectors that nearly glimpsed the Higgs late last year. It is being removed to make room for the new machine.

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Buried beneath the plains of Illinois is a monster of a machine designed to mince matter into its most fundamental parts. It's called a particle accelerator, and it relies on 1,000 giant superconducting magnets, 700 scientists and engineers, and more than $10 million in annual electricity bills to keep on running 24 hours a day, 7 days a week.

This accelerator has a twin, tucked underneath the Alps just outside of Geneva. And researchers at each of these immense devices share one single-minded, unlikely goal: They are searching for an elusive speck of matter. The object of their search is unimaginably tiny, and so obscure that almost no one outside the world of physics has ever heard of it. Nevertheless, the stakes are high: Whichever group finds it first is likely to earn a Nobel prize.




At the center of all this scrutiny is an elementary particle known as the Higgs boson. Nobel prize-winning physicist Leon Lederman has dubbed the Higgs the "God particle," and the divine analogy is not altogether unwarranted. If the Higgs really exists (there is still some doubt), and if it can be identified, scientists will have answered a question that was once asked only by philosophers and lunatics: Why do objects have weight? Moreover, a sighting of the Higgs could shake the entire foundation of physics-bringing with it intimations of particles that no one has yet imagined, and forces that defy all known laws. Many investigators believe a "new physics" is around the corner, and they expect the Higgs to be their guide.




At first glance, the Fermi National Accelerator Laboratory, or Fermilab, in Batavia, Illinois, does not appear to be a place where cosmic events are poised to transpire. As you enter the sprawling 6,800-acre campus less than an hour west of Chicago, the first thing you notice is emptiness: The area is strangely barren, save for a few clusters of industrial buildings and a roaming herd of buffalo. The only hint of the power that resides here is a giant ring of dirt 4 miles around, rising 20 feet above the plains.




That loop is the outline of a circular underground tunnel, the particle accelerator known as the Tevatron. The Tevatron is so big that it's not a machine in the conventional sense of the word; it's a part of the landscape. Its purpose is to get a beam of protons and a beam of antiprotons moving in opposite directions as fast as possible-and in the high-powered Tevatron, fast means 99.99999 percent of the speed of light. The protons and antiprotons circulate inside a tube only a few inches wide; the rest of the tunnel is filled with wires, walkways, and 15 miles of pipes carrying liquid helium to the superconducting magnets.




Once the proton and antiproton beams are speeding along, they're routed into a violent head-on collision. When protons smash into antiprotons, they annihilate each other in a blast of pure energy. The shards that result often include new particles-one of which just might be the Higgs.




Two detectors, each the size of a three-story house, punctuate the Tevatron's vast ring. The proton-antiproton collisions are timed to occur within the detectors, which contain a network of wires, silicon detectors, and microchips-5,000 tons of electronics in all. The role of the two detectors is straightforward: Take a snapshot of each collision and the spray of particles that results. Sounds fairly simple, until you realize that 2.5 million collisions occur in the Tevatron's detectors every single second. And only one collision in billions has a chance of producing the sought-after Higgs.




"These machines are microscopes, plain and simple," explains Chris Hill, a theoretical physicist at Fermilab. We're sitting in his office overlooking the spot where the rolling plains of Illinois meet the newly built subdivisions spreading westward from Chicago. Hill's modest office is a jumble of computer printouts, old mathematics textbooks, and bits of chalk-an ironically untidy setup considering that he and his colleagues are determined to uncover whatever hidden order there is in the universe.
Physicists have come a long way toward ordering the universe during the past hundred years or so. First they determined that atoms are the building blocks of everything around us; then they began splicing up atoms into ever-smaller bits and pieces. The electron came first, popping out of J.J. Thomson's British laboratory at the turn of the last century; the proton and neutron followed a few decades later. Those three particles join together in various combinations to form all 118 elements of the periodic table.