The Hunt for the God Particle

Whenever a proton and an antiproton collide within a particle accelerator-and remember, such events occur at the staggering rate of 2.5 million per second-those explosions are picked up by the Tevatron's two detectors, which are known as CDF and D (pronounced dee-zero). The electronic sensors within the detectors sift through the elementary rubble, ultimately discarding many of the collision events and selecting only the choicest ones for later analysis.




With a knack for understatement that only a particle physicist could manage, Franco Bedeschi, a leader of the CDF team, describes his project simply as "large." The reality is that the work of detecting, identifying, and tracing the scores of new particles produced by every collision is something akin to tracking the pulp that's scattered when a truck carrying ripe tomatoes jackknifes at 50 miles an hour. It's an intricate, and messy, business. Complex computer programs compare and contrast trillions of collisions over a period of years, searching for anomalous trends in the data.




What will scientists see, if and when they manage to capture the Higgs? Like everything in this business, it's not straightforward. The collisions themselves can be "seen" on a computer screen-each one is translated into an image that looks like a tangle of lines shooting off from a central point. But the Higgs won't show up on any of these collision snapshots, because almost as soon as it appears, it evaporates into a pair of exotic particles called bottom quarks. Unfortunately for the Higgs hunters, bottom quarks can also be produced in a variety of other ways. Fortunately, however, the bottom quarks that are produced by the Higgs possess a specific energy level. Thus the eureka moment will come when the physicists' computer programs have sifted through the debris of some 500 trillion collisions and found a surge of bottom quarks with the recognizable Higgs energy signature.




Higgs researchers are up against more than just the inscrutable laws of physics: they're also battling each other. Late last year, scientists at CERN found tantalizing hints that the Higgs had already been produced in their particle accelerator. More data were needed to confirm, but CERN was on the verge of shutting down for a much-anticipated upgrade. It was a dilemma: Staying open meant delaying construction on CERN's planned new accelerator, the Large Hadron Collider. Shutting down meant leaving the field open for Fermilab. CERN's director opted to close.




CERN's Large Hadron Collider, which won't go online until at least 2006, will be seven times as powerful as Fermilab's Tevatron and will produce 100 times more collisions every second. "It is not a small, incremental step, it's really a new giant step," says Peter Jenni of CERN. Fermilab's Harry Weerts is more forthcoming about the power of the machine-to-be, conceding: "If the LHC was on right now, it would not be worth turning on the power at CDF and D."




But whether Fermilab catches the Higgs before 2006, or CERN grabs it later, the real question is, What's the payoff? The Higgs is expected to do a lot more than explain mass; physicists hope it will point toward a whole new foundation for 21st century physics. Some anticipated directions would be fairly straightforward extensions of the Standard Model. Others are downright bizarre, postulating the existence of various dimensions in addition to our standard three, along with a bevy of new particles. And there's always the possibility that no one has any idea what physics will look like in 20 years.




But that doesn't stop scientists from wondering. And for Hill and many others, the tantalizing Higgs boson holds many of the answers. What the Higgs will tell us, he says, is simple: "What are the laws of physics from here on out?"