At lab where atom is probed, scientists make way for geese

At Fermi National Accelerator Laboratory - where scientists probe the atom for clues to the birth of the cosmos - an early-morning visitor may be met at the door by a goose. Like the other wild creatures who share the site with the world's most powerful particle accelerator, it thinks it owns the place. A suspicious scrutiny of strangers is in order.

This is part of the Fermilab mystique. A wider ecological awareness enhances a creative environment in which physicists work to understand the basic structure of matter. The laboratory has established a conservationist tradition, providing a home for two bison herds, deer, and flocks of waterfowl, plus breeding projects for sand hill cranes and trumpeter swans. And a patch of primitive Illinois prairie is beginning to reappear within the ring of raised earth that covers the four-mile circumference of the accelerator's high-vacuum tube, in which subatomic particles will race at 99.999956 percent of the speed of light.

Such is the backdrop for what may be the opening of a new act in the historic drama of scientific discovery.

Physicists here sense that the new, more-powerful accelerator, called a Tevatron, may put their present understanding of particle physics to a severe test. They suspect - and hope - that it will reveal phenomena that lead to a deeper understanding of basic natural forces. Fermilab's ebullient director, Leon Lederman, says they could move ''beyond the area where theorists can safely project their theories.''

One way the Tevatron, scheduled to rev up to full power in the fall, promises to extend physicists' horizons is by prolonging the life of certain short-lived particles. According to relativity theory, the faster a particle travels, the longer it ''lives,'' as seen from the laboratory viewpoint. This is called time dilation. It means, in effect, that the physicist would perceive a clock traveling at the speed of the particle as running more slowly than does a laboratory clock - that is, the particle lives longer before decaying because its time runs more slowly.

Certain particles (called Tau mesons), created in the collision of protons, will be energetic enough - travel fast enough and live long enough - to leave tracks from 6 to 10 millimeters long. That's enough for good measurements, whereas former tracks of only 1 or 2 millimeters were frustrating to study, explains Chris Quigg, head of Fermilab's Theoretical Physics Department. Such considerations concern the practicalities of doing experiments and are ''crucial , making it easier to do better physics at higher energies,'' he says.

Twelve years of effort and an outlay of some $130 million from the US Department of Energy have brought the Tevatron to the point of opening a new window on the unknown, says Fermilab director Lederman. Meanwhile, it has already produced some practical side benefits in the realm of the known.

Dr. Lederman explains that young scientists working on the project are learning more than esoteric physics. The new machine incorporates significant advances in engineering.

For example, protons within the accelerator tube are held to their circular course by powerful magnets. The Tevatron uses superconducting magnets that are smaller and use less electric power than conventional magnets of comparable strength. When cooled by liquid helium to within a few degrees of absolute zero (-273 degrees C. or minus 459 degrees F.), the magnet coils lose their electrical resistance. They become superconducting - an electric current, once started, circulates through them without decaying.

Tevatron represents the first large-scale use of this technology, which now may find wider application in the electric power industry.

Presidential science adviser George A. Keyworth II has said he considers basic scientific research, like Fermilab's, a training ground for the technical talent the United States needs to compete effectively in world markets.

Although building the Tevatron has produced such technological spinoffs as the superconducting magnets, the new insights physicists hope to gain with the machine have no immediate practical applications. Their benefits lie in expanding the base of human knowledge and in generating new perspectives on the cosmos.

Lederman notes that the lure of uncovering the basic structure of the universe is strong.

''I think young kids go into science because it's natural,'' he says. ''A little kid will ask all the right questions. Why is the sky blue? Why don't the stars fall down? These are high-energy physics questions. Then they go to school and they get all of that stuff beaten out of them. But some of them don't grow up. They become high-energy physicists, and molecular biologists, and space scientists.''

Stressing his interest in nurturing the physicists of the future, Lederman notes proudly that Fermilab welcomes young inquirers. A series of Saturday lectures and discussions is held at the lab for students from area high schools. For the physicists who participate, these sessions with schoolchildren represent a sojourn from a world that can seem incredibly abstruse to laymen.

Consider, for example, how the energies employed at Fermilab's accelerator are measured - in terms of electron volts (eV). A proton or electron gains an energy of one eV when it is accelerated by a voltage difference of one volt. Fermilab's new accelerator already has beams of 800 billion eV (800 GeV) protons. (G for giga, the metric term for billion.) Within a year, it should reach its design level of 1,000 GeV or 1 TeV (T for tera, the metric term for a trillion.) Hence the accelerator's name - Tevatron.

After a shutdown to accommodate ongoing construction and further tuneup, the machine should be running again in the late fall at close to its full 1,000-GeV energy. In two more years, with all related construction finished, the facility should provide both a beam of 1,000 GeV protons and one of 1,000 GeV antiprotons - the antimatter version of protons - traveling in opposite directions. Antimatter is like ordinary matter except that certain properties, such as electric charge, are reversed. These beams will intersect to give physicists particle collisions at 2,000 GeV.

That's nearly four times the energy available in the collider at the Center for European Research in Nuclear (particle) Physics (CERN) at Geneva, which has been the most powerful in the world.

Research at CERN last year put the capstone on what physicists call their standard model of matter's underlying nature. This model stands, Lederman says, at the ''boundary between what we understand and our ignorance.'' With the Tevatron, physics will move beyond that boundary.

The standard model is a combination of two major theories. One explains protons and neutrons, which form atomic nuclei, and other related particles as being themselves composed of smaller entities called quarks.

The other theory (the electroweak theory) explains the weak force involved in some forms of radioactive decay as just another manifestation of the familiar electromagnetic force. This theory unifies two of nature's basic forces. It passed a crucial test when its prediction of new particles called W and Z was confirmed by discoveries at CERN.

Since then, a few phenomena that don't fit the standard picture have been seen at CERN and, to a lesser extent, at Fermilab and elsewhere. They hint that something new may be just over the energy horizon. Sensing this, Lederman observes, with an overtone of anticipation, that ''many a beautiful theory has been killed by one ugly fact.''

But, he adds, ''the trouble is, these are ones and twos of events and, therefore, until you get many, many events, we can't come to grips with the problem.'' That, he says, is what he expects from the Tevatron - many, many nonconforming events to test the standard model.

Poised as they are on the threshold of exploring a new scientific frontier, Fermilab physicists are working intensively. Yet, in keeping with the wider concerns that have long characterized the lab, they are careful to make room in their lives for the curiosity of the young - and for the territoriality of geese.

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