THE American supercollider particle accelerator project is dead. Long live its European counterpart.
That's the hope with which both American and European particle physicists greet the new year. It's a year for decisions as to whether Europe will proceed with its accelerator project and, if it does, to what extent American physicists might join in.
Scientifically, the stakes are high on both sides of the Atlantic. ``The way things look now, if we are going to take part in the next phase of high energy [physics] exploration,'' it will be in Europe, says physicist Alfred Goshaw at Duke University in Durham, N.C. He adds that European colleagues with whom he has talked ``would be delighted if the US were to play a major role'' in their project. He explains that these colleagues worry that, without strong American participation, the cost of the new machine will strain Europe's ability to fund basic physics and narrow the scope of its research in this field.
Like the superconducting supercollider (SSC) that the United States Congress canceled, the European machine is designed to explore such basic questions as why matter has mass. The $11 billion American SSC would have collided protons with antiprotons -
the protons' antimatter twins - in collisions that had a total energy of 40 trillion electron volts (40 Tev). That corresponds to a temperature of about 500,000 trillion degrees. The European Large Hadron Collider (LHC) will collide two proton beams together with a total energy of only about 14 Tev - ``only'' about 160,000 trillion degrees. It's called a hadron collider because protons belong to a class of particles called hadrons. The SSC would have raced particles around a 54-mile ring. The LHC ring will be only 17 miles long. It has to fit into an existing tunnel where another accelerator already is operating at the European Laboratory for Particle Physics (CERN) at Geneva.
Duke's Professor Goshaw says it ``is going to be much harder'' to work with the smaller, less powerful LHC. But it can do the job physicists want. ``It's the only hope we have now to look for'' the mechanism by which matter acquires its mass, Goshaw says.
At this point, European and American physicists are cautiously eyeing each other. CERN's council confirmed its commitment to the LHC at its Dec. 16 meeting in Geneva. Member states won't give final approval before next summer at the earliest, however.
MEANWHILE, incoming CERN director Christopher Llewellyn-Smith has reported the latest ``realistic'' total cost estimate as 2.6 billion Swiss francs ($1.8 billion). That includes costs of experimental equipment and initial experiments for a start-up in 2001 or 2002. Cost of the LHC itself would be 2.23 billion Swiss francs ($1.55 billion). That's far less than the projected SSC cost. But it still strains budgets for CERN's 19 member countries. If their annual subscriptions are to remain level, as they expect, nonmember countries participating in the LHC project will have to come up with an additional 500 million Swiss francs ($350 million).
This is where the United States could help. Goshaw is part of a collaboration that has developed detector technology for the SSC that might be useful in LHC experiments. Department of Energy Secretary Hazel O'Leary has asked the department's High Energy Physics Advisory Panel for suggestions on the future course of US particle physics research that have ``a truly international flavor.'' The panel is due to report in May.
Meanwhile, Goshaw says American and European physicists will explore possible participation in the LHC informally. They will do it first as individual research groups. But the United States physics community needs a common approach to this issue, Goshaw says. One of the major decisions now facing the US physics community is ``what role we will play in the LHC in collaboration with CERN.''