Physicists sum up possible glimpses of elusive particle

If signs are strong enough, they must decide whether to defer the time-consuming project of replacing their massive particle accelerator and instead push their aging equipment for all-out "discovery" in hopes of beating out their American rival.

"Anything can happen," said Neil Calder, spokesman for CERN, the European Laboratory for Particle Physics.

During recent months CERN has stepped up power on its Large Electron-Positron collider to the outer limit to see whether it could discover the Higgs. The result was that three of the four LEP detectors recorded what appeared to be tantalizing shadows of the particle.

Finding the Higgs, theorized to be the source of the mass of everything in the universe, is expected to worthy of the Nobel prize for physics.

The long-sought particle was named for British physicist Peter Higgs, who postulated its existence more than 30 years ago to explain how atoms and everything else in the universe have weight.

The Higgs theory is that the usually invisible bosons create a field through which subatomic particles such as quarks and electrons pass.

The particles that pass through slowly pick up more inertia, and mass. The ones that pass through easily remain lighter.

On Thursday morning CERN shut down the LEP in preparation for dismantling the 11-year-old accelerator and starting a five-year construction project to instal much more powerful equipment, to be called the Large Hadron Collider. This is eagerly awaited by the physics world because it is expected to give scientists much better ability to examine the building blocks of the atom.

But until a final decision is made, CERN could switch the LEP back on and make a further push in the 27-kilometer (17-mile) circular tunnel under the Swiss-French border.

If the LEP is shut down for good, many scientists think the Fermi National Accelerator Laboratory outside Chicago would have a good chance of finding the Higgs before CERN comes back on line.

Fermilab, which has been upgrading its own facilities for four years, is to start its Higgs experiments next spring.

CERN already has postponed the LEP shutdown once _ at the end of September. The one-month extension made little financial difference to the laboratory, but a continuation will likely cause costly delays in building the dlrs 1.8 billion LHC.

It also will likely throw off planned experiments for top physicists around the world.

(AP)