BREAKTHROUGH OF THE YEAR:
Breakdown of the Year: U.S. Particle Physics

Particle physicists in the United States would probably like to forget 2005. Budget woes forced the cancellation of two major experiments just as researchers were about to start construction. That leaves none in the works to replace those currently studying particles called quarks--the sorts of experiments that have long been the heart of the field. At the same time, the U.S. Department of Energy (DOE) asked physicists to consider which of two existing particle colliders they would rather shut down early to save money.

Physicists got a shock in February, when DOE nixed BTeV, a $140 million experiment that would have run at the Fermi National Accelerator Laboratory (Fermilab) in Batavia, Illinois (Science, 11 February, p. 832). Using beams from Fermilab's Tevatron collider, BTeV would have studied bottom quarks, heavier, unstable cousins of the down quarks found in protons and neutrons. BTeV researchers were expecting to get the final go-ahead for construction.

Early end? Either SLAC's PEP-II collider (above) or Fermilab's Tevatron could shut down ahead of schedule. CREDIT: STANFORD LINEAR ACCELERATOR CENTER

In May, DOE's Office of Science requested a study, due early next year, of the relative merits of shutting down either the Tevatron or the PEP-II collider at the Stanford Linear Accelerator Center in Menlo Park, California (Science, 27 May, p. 1241). The Tevatron smashes protons into antiprotons at the highest energies achieved to make top quarks and other particles; PEP-II collides electrons and positrons and cranks out bottom quarks. Researchers plan to turn off PEP-II in 2008 and the Tevatron in 2009, but decommissioning one of them earlier might free up money for future projects.

Meanwhile, researchers in Europe are assembling the Large Hadron Collider at CERN, the particle physics laboratory near Geneva, Switzerland. Scheduled to start up in 2007, the $7.7 billion machine might produce the long-sought Higgs boson, the particle thought to give others their mass. At the same time, physicists in Japan have their KEK-B collider producing bottom quarks and are studying wispy particles called neutrinos. (Fermilab is also pursuing neutrino physics.)

But particle physicists from Europe and Asia aren't celebrating the passing of the torch from the United States. They say a strong U.S. program is essential for the survival of the field, especially if they hope to build the proposed International Linear Collider (ILC), a multibillion-dollar global facility that most see as the future of particle physics. "It is very clear that without the participation of the U.S. it is impossible" to build the ILC, says Akira Masaike of the Japan Society for the Promotion of Science in Washington, D.C.

On that front, at least, 2005 brought some reasons for optimism, says Fred Gilman of Carnegie Mellon University in Pittsburgh, Pennsylvania. Physicists from the United States, Europe, and Asia united in their commitment to the ILC as never before. "Before, the international effort was the sum of three parts," Gilman says. "Now there is central leadership." And officials in DOE's Office of Science remain enthusiastic about the ILC, Gilman says. Physicists plan to have a preliminary design--and a price tag--for that dream machine by the end of 2006.

Online Extras on U.S. Particle Physics

The Story in Science

J. Mervis, "Caught in the Squeeze," Science 307, 832 (2005)

C. Seife, "High-Energy Physics: Exit America?," Science 308, 38 (2005)

C. Seife, "Physics Research Gets a Boost and a Warning From Its Funders," Science 308, 1241 (2005)

J. Mervis and A. Cho, "Costs Force NSF to Cancel Brookhaven Project," Science 309, 1163 (2005)

Other Links

Fermilab
A presentation on the tevatron is offered.

SLAC
Information on PEP-II is provided.

Brookhaven National Laboratory
Information about the RSVP experiment is provided.

CERN
The Large Hadron Collider Web site offers an outreach page.

Japan's KEK collider

The International Linear Collider