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The United States is not ready to build any more new particle accelerators, two separate panels of scientists have told the government. But it should press on with the conceptual design of a new linear accelerator, as well as researching options for other machines that might be built early in the next century.

While these ideas are being developed, the panels say, the top priorities in high-energy physics should be US participation in the Large Hadron Collider (LHC) project at CERN, the European Laboratory for Particle Physics in Geneva, Switzerland, and securing increased funding for particle physicists at universities.

The High Energy Physics Advisory Panel (HEPAP), which advises the Department of Energy on its $700 million-a-year highenergy physics programme, last week endorsed one of the reports, prepared by a panel chaired by Frederick Gilman of Carnegie-Mellon University in Pittsburgh.

The panel says that the Stanford Linear Accelerator Center in California should create a conceptual design for an electron-positron linear collider “in close collaboration”. But it says emphatically: “This is not a recommendation to proceed with construction.”

At the same time, a National Research Council panel chaired by Bruce Winstein of the University of Chicago issued a substantially similar set of recommendations. Like HEPAP, it calls for the development of a conceptual design for a linear accelerator with an collision energy of up to 1.5 TeV.

Recommending that research should be “vigorously pursued” into technologies for future muon and very large hadron colliders, the Winstein panel says this effort “should focus on a reduction of cost through the use of advanced technologies”. The report does not express a view on which of these concepts is most promising.

Energy department officials welcome the modest consensus struck by the reports. “Everybody agrees we need to bring the design forward before approving construction” of a new linear collider, says Bob Diebold, HEPAP's executive secretary.

Winstein says his panel's 160-page report was supposed to make the case for particle physics to Congress and a wider public.

“We feel it is our obligation to speak more clearly and more frequently to the public,” Winstein says.

US plans to participate in the LHC project have already received some unwanted attention from the Congress. Money for the LHC was included in a list of “questionable funding increases” issued by Bob Livingston (Republican, Louisiana), the chair of the Appropriations Committee in the House of Representatives.

Officials had expected trouble for the project in Congress, but they believe that Livingston's prime motive is to use the international LHC agreement to obtain leverage with the administration, not to end US participation in the project.