Suspense on a subatomic scale
Posted: Tuesday, June 26, 2007 5:59 PM by Alan Boyle
Who will find the "God particle" first? Next year, CERN is due to start up its Large Hadron Collider on the French-Swiss border to hunt for the Higgs boson, the elusive subatomic particle that is thought to give rise to mass. But some scientists are wondering if Fermilab's Tevatron collider in Illinois might beat the LHC to the punch. For now, the wondering hasn't gone much beyond hints and rumors. Nevertheless, the Tevatron's operating life is likely to be extended to see if there's something real behind those rumors.
Over the past few weeks, the rumors have surfaced on physicists' Web logs as well as Wired's Web site, focusing on what's said to be a small amount of data from the Tevatron's DZero experiment. Just this month, the DZero team announced that they had identified a new type of "triple-scoop" baryon - but so far, nothing has been published relating to the purported Higgs results.
Bagging the Higgs boson would be a big deal because it's the only particle whose existence is predicted by the Standard Model but has not yet been found. The Standard Model, which some have called the "theory of almost everything," is a description of the subatomic world that has served exceedingly well as a guide for technologies ranging from microwave ovens to hydrogen bombs.
Over the past century the Standard Model has been repeatedly fleshed out and nailed down - but if it turns out that the theory is fundamentally wrong, that could force physicists to rewrite their cosmic rulebook. On the plus side, such rewritings typically lead to dramatic shifts in science and technology, as they did in the case of quantum theory and relativity.
Based on the reports that have emerged so far, including chats I've had with physicists at Europe's CERN research center over the past week, it appears safe to say that there's something intriguing about the DZero data, but not yet enough statistical significance to the results. More runs are required to determine whether what has been seen is just a crazy blip or true evidence of the Higgs boson.
The big question is, how much longer will the Tevatron be around for those future runs? The traditional expectation has been that the collider would be shut down in 2008, and that particle physicists from the United States as well as other parts of the world would turn their attention to the more powerful Large Hadron Collider.
But Fermilab spokeswoman Judy Jackson told me that an advisory panel appears likely to recommend keeping the Tevatron around through 2009. "It is far from a done deal, but it looks as if that is going to be what they will recommend," she said Monday.
That recommendation would have to be pushed up the chain, through the Department of Energy and on to Congress, Jackson said. But the prospects look good, based on what the scientists are seeing. "It does illustrate the fact that there is a possibility that people could find something interesting," she said.
There are a couple of other factors at work: The schedule for starting up the Large Hadron Collider has faced some setbacks, and this means the particle physicists involved in the Tevatron collaborations (DZero as well as CDF) might be more willing to stick around. And Jackson said that the Tevatron has been working better than ever.
"The Tevatron is exceeding everyone's expectations. ... The experiments are getting, I think the technical term is, a boatload of data," she said jokingly.
Jackson said the Tevatron was in top form primarily because scientists had found some "really clever ways of getting more collisions per second out of the machine." If the machine is working well, and there’s not yet another game in town, and the promise of a big scientific payoff is out there – why not keep it going?
"The whole thing is obviously about the science," Jackson said.
During my visit to Europe's research center, one of the top scientists behind the Large Hadron Collider acknowledged that the Tevatron was still in the hunt for the Higgs.
"There is a possibility, there is a window for Fermilab still at this moment for Higgs physics," said Jos Engelen, CERN’s chief scientific officer and deputy director general. "The longer we wait, the higher the probability that Fermilab discovers something that we wouldn't mind discovering ourselves here."
But what exactly might Fermilab have discovered? On one hand, some of the rumors indicate that the results match up with the Standard Model’s predictions for the Higgs boson’s characteristics. On the other hand, particle physicist Ian Hinchliffe told me the Higgs results just might be, well, non-Standard.
"If the result is right, then it’s not the Standard Model Higgs," said Hinchliffe, who is a theorist at the Lawrence Berkeley National Laboratory as well as the physics coordinator for the U.S. Atlas collaboration at the LHC. The rate of particle production appeared to be too high, a result that could suggest there’s a family of at least five Higgs particles out there, he said.
No matter what the result turns out to be, the last word will likely go to the LHC rather than the Tevatron - just because the LHC is capable of producing collision energies several times as high. Fermilab is heavily involved in the LHC project as well as the Tevatron, so the lab has all its bets covered.
On Friday, as a matter of fact, Fermilab conducted the first tests on LHC magnets that had to be modified in the wake of an untimely failure in March, Jackson said."We did a test of the retrofit that people had to do, and the retrofitted magnet performed like a champ," she said.
For Jackson and the rest of the Fermilab team, that was a real day-brightener. And for the rest of us, there's this cover art from the May issue of Symmetry magazine. Thanks to cartoonist Roz Chast, the elusive Higgs boson never looked so good.
While you're paging through Symmetry, don't miss the picture story about Katie and Adam Yurkewicz. As the U.S. communications representative for the LHC, Katie Yurkewicz was our main host for last week's visit to CERN - and deserves thanks for putting the "big" in the Big Science Tour.
Previously from the Big Science Tour: The science behind the tour ... Living in the Web's cradle ... Inside the big-bang machine ... Toiling in the fields of physics ... Inside the antimatter factory ... First, the Web ... now, the Grid.
