BERKELEY — It was a great machine, the mighty Bevatron. Less than two years after it was switched on in 1954, the billion-electron-volt particle accelerator--the most powerful atom smasher in the world at the time--did precisely what it was designed to do. It discovered an arcane slice of the universe called antimatter, thus confirming complex mathematical models of how the universe really works.
At the same time, it made itself obsolete.
Once it had smashed subatomic protons together with enough energy to create antiprotons and antineutrons--small atom fragments with characteristics that are the exact opposite of normal--the barn-sized Bevatron was a multimillion-dollar machine with no clear task.
Rather than junk the machine, or cannibalize it for parts to build a larger accelerator, clever and curious physicists at the Lawrence Berkeley Laboratory retooled the Bevatron, rechristened it the Bevalac and then put it back on the cutting edge of physics research.
It is perhaps the best example of what can be done with old atom-smashers--a subject of special concern as Congress debates whether to spend $4.4 billion to build the most powerful particle accelerator ever, the new superconducting super collider.
An old electron accelerator at Stanford, for example, has been converted to a synchrotron light source. This device is similar to an X-ray machine and has become popular among corporate and government clients for analyzing the inner structure of new composites and other materials.
"Each (electromagnetic) wavelength can explore a different property in the structure of matter," said Edwin (Ned) Goldwasser, associate director of the SSC Central Design Group at the Lawrence Berkeley Laboratory here. "Things we can see in X-ray . . . are things we can't see at a higher-energy (wavelength) or a lower energy, and vice versa."
Corporate and government researchers also are paying customers at an old University of California, Davis, proton accelerator. The 60-inch cyclotron was built at the University of California, Berkeley, by Ernest O. Lawrence, who won the Nobel Prize in 1939 for inventing and developing such machines. The 48-year-old machine now is used for several commercial applications: to analyze air-pollution samples, measure acid rain, make nuclear medicine to fight cancer and even authenticate the inks and papers of old documents.
To be sure, dozens of old accelerators have done their duty, been dismantled and forgotten. Others have been cannibalized for their parts, especially their big iron magnets, which usually are employed in the massive computerized detectors that analyze the collisions in new accelerators.
However, a surprising number of old machines--nearly a dozen were located in an informal survey by The Times--still have science to do, either as an element in a more modern accelerator, as synchrotron light sources, opening up vistas in nuclear science or developing new cancer treatments.
Of all of them, the Bevatron may be the best example, Goldwasser and others said.
"The interesting thing is that in the 30 years following (the discovery of antimatter), the facility has somehow been able to stay on the cutting edge of particle research," said Charles Hurley, a spokesman at the Lawrence Berkeley Laboratory, which includes three other operating atom smashers, as well as the original five-inch cyclotron invented by Lawrence in 1930.
"It shows that you can't predict the opportunities that can arise when you build these facilities and staff them with imaginative people," Hurley said.
Perhaps the most imaginative use for the Bevatron arose in the early 1970s, when the machine was modernized and linked up with another nearby accelerator, a heavy ion linear accelerator. Together, the two machines, known collectively as the Bevalac, accelerate entire atoms--even the heaviest uranium isotopes--to nearly the speed of light.
For nuclear physicists and astrophysicists, this is a useful advantage over regular accelerators, which use only fragments of hydrogen and other extremely light atoms.
"From two such ancient parts, we created this unique machine," said James Symons, associate director of the federal facility's nuclear science division, "and it is still unique today, although other machines are now being built to do the same thing."
He said the ability to accelerate heavy ions lets scientists approximate on a small scale a number of curious space phenomena, such as the extreme nuclear densities experienced after a star collapses in on itself in a supernova.
Nuclear physicists, he added, use the accelerator to work on formulating an equation of state for nuclear matter--that is, to see if atomic nuclei change states, as water molecules change into ice and steam. This is done by smashing together heavy ions to generate very high temperatures and pressures, and make atom fragments with extreme numbers of protons or neutrons.