Fermilab

We invest scarce resources in basic research because experience has shown that in the long run it pays off.

Each year, the taxpayers of the United States invest about $700 million of the federal budget in high-energy physics. What benefits do we get for our investment in this esoteric science? As an Illinois congressman once succinctly put it, "We've got enough quarks already. What do we need another one for?" It's a fair question, and it deserves an answer.

One response is that the value of basic research in "pure science" such as high-energy physics lies in the determination to understand and explore, and in the challenge of using our highest human capacities to learn the truth about the nature of nature, for its own sake. A good case can be made that research in pure science is one mark of a high level of civilization.

Besides cultural considerations, we invest scarce resources in basic research whose application is not immediately obvious because experience has shown that in the long run it pays off in concrete, measurable, economic and social benefits. Pure science lets us move beyond fiddling with the knobs of the natural world to an understanding of how the universe really works when we look inside. E.O. Lawrence often kept the cyclotron in Berkeley running all night in order to produce enough radioisotopes for California hospitals to use in treating cancer. He began a tradition of using accelerators for medical diagnosis and treatment.

The story of the scientific exploration of the atom and the particles within it over the last hundred years is an account of the enormous power of basic research to discover and explain. It is equally the story of a century of technological, economic and social change directly linked to this research.

Discovery of the electron In 1897 J.J. Thomson discovered the electron, using a kind of particle accelerator, a cathode ray tube, that accelerated a beam of negatively charged particles between electrical terminals and made a phosphorescent green glow around the positive terminal. (Wilhelm Roentgen had used this same device in 1895 in his discovery of the particle beams that gave us x-ray technology.) Cathode ray tubes using this same principle of particle acceleration now sit in television sets in hundreds of millions of American homes, and illuminate the screens of millions of computers and scientific and medical instruments.

Finding the nucleus

In 1909, students in the laboratory of physicist Ernest Rutherford directed alpha particles from a lump of decaying radium at sheets of gold foil. The unexpected way the particles scattered when they hit the foil led Rutherford to the discovery of the atomic nucleus in 1911. Rutherford's discovery was a scientific leap forward. However, no one, least of all Rutherford himself, foresaw the enormous consequences it would have. Rutherford is reported to have said, "Anyone who expects a source of power from the transformation of these atoms is talking moonshine." He made his statement five years before the first demonstration of nuclear fission. Rutherford's words have an ironic ring in a world transformed by nuclear energy.

Quantum theory

In the 1920s, increasing data from experimental discoveries about the nature of the atom led to the theory of the structure and behavior of atoms we call quantum mechanics, and to an utterly new understanding of nature. From this new knowledge came lasers and solar cells and, in 1947, the discovery of the transistor, the basis of all modern electronics and the age of information.

Particle accelerators

To get a closer look at the nucleus Rutherford had discovered, his students--the first nuclear physicists--needed a better source of particles. The particle accelerator they invented was the great-granddaddy of all those built ever since. They had discovered that the particle accelerator gave them the way into the atomic nucleus.

With their new accelerator, Rutherford's students found that the nucleus was itself composed of particles, the proton and neutron. Getting a better look at those particles required a particle accelerator of higher energy. Thus, the science of accelerator physics was born--the art and craft of using advancing scientific and engineering knowledge to build accelerators of higher and higher energies to go deeper and deeper inside the atom. Particle accelerators have revealed the structure of the atom, its nucleus, the protons and neutrons within the nucleus, and even the particles inside them. Accelerators have shown us the powerful forces that play among the particles inside the proton and neutron. Along the path of discovery came technology with benefits for society that go far beyond purely scientific applications.

Lawrence in the 1930s and 1940s

In 1930, the great American experimental physicist E.O. Lawrence built the first successful circular particle accelerator. It was four inches in diameter, and he could hold it in his hand. In two decades, Lawrence's genius for accelerator building, and the particularly American brand of ingenuity that flowered in his Berkeley laboratory, brought the particle accelerator from a scientific curiosity to a powerful and sophisticated research tool. As accelerator followed accelerator, Lawrence and his pioneering research group overcame the pitfalls and unleashed the enormous potential of particle accelerator technology.

Synchrotron radiation has become an indispensable tool for thousands of researchers in such fields as materials science and engineering, surface chemistry, biotechnology, medical imaging and environmental science.

Accelerator physics in medicine

In the 1930s, Lawrence often kept the cyclotron in Berkeley running all night in order to produce enough radioisotopes for California hospitals to use in treating cancer. He began a tradition of using accelerators for medical diagnosis and treatment. Today, patients receive cancer treatment using beams of neutrons produced by accelerators whose main job is to produce protons for physics research. In another therapeutic approach, doctors at Loma Linda University Medical Center now treat over 100 cancer patients each day with protons from a synchrotron designed and built at Fermi National Accelerator Laboratory. Medical facilities around the world are investigating this technology. Linear electron accelerators in thousands of hospitals around the world treat millions of cancer patients every year.

Computer-aided tomography, the CAT scan, perhaps the most significant advance in medical radiography since the 1895 discovery of x-rays, originated in particle detection methods developed by high-energy physicists. The underlying magnet technology for Magnetic Resonance Imaging (MRI) came from particle physics research. Positron Emission Tomography (the PET scan) uses crystals of a material developed for high-energy physics particle detectors.

Linear accelerators at Stanford

Starting in the 1940s, physicists at Stanford built a series of increasingly powerful straight-line electron accelerators, or linacs, using microwave devices called klystrons, whose high-power microwave technology is now the basis for radar installations throughout the world. Experiments in the 1950s and 1960s used these machines to measure the diameter of the proton and neutron. Few physicists expected any big surprises from continuing experiments. But in the late 1960s, much as Rutherford had done 50 years earlier, they found an unexpected scattering pattern at the new 20 GeV SLAC linac. To their amazement, the pattern produced by the big step up in energy suggested that the proton and neutron were not point-like elementary particles but had something even smaller inside them; this "something" turned out to be quarks.

Synchrotron radiation

Accelerator physicists have always had to contend with a problem that occurs whenever charged particles are accelerated: the particles lose some of their energy to the emission of light in a phenomenon called synchrotron radiation. At first physicists considered it simply an unavoidable energy drain, but researchers used developing technology to turn it into an intense, tunable source of useful radiation. Synchrotron radiation has since become an indispensable tool for thousands of researchers in such fields as materials science and engineering, surface chemistry, biotechnology, medical imaging and environmental science. Now it has found its way into industrial applications in a process called x-ray lithography, used to produce advanced microchips with extremely dense arrays of electronic components. Synchrotron radiation is also used extensively in studying the structures of large biological molecules such as hemoglobin. One team of scientists working at SLAC was recently able to determine the structure of the gene responsible for Lou Gehrig's disease. Another group is using this radiation to develop drugs to block the action of a key enzyme in the replication of the AIDS virus.

Fermilab

Working at a new energy level, experiments at Fermilab and at new European accelerators began to fit the complicated list of subatomic particles into a compact new picture that physicists call the Standard Model. The Standard Model includes quarks, other particles called leptons, and the forces that act on them. In 1977, experimenters at Fermilab discovered a fifth quark, a discovery that set off the search for the sixth, or top quark, the last undiscovered quark of the Standard Model. In the late 1970s, Fermilab took advantage of another jump in accelerator technology, adapting its accelerator to use colliding beams, rather than one beam hitting a stationary target. In 1983, Fermilab completed the Tevatron, the world's first superconducting synchrotron, doubling the energy of the accelerator to make it a far more useful scientific instrument and to bring the top quark within range of discovery. Fermilab scientists discovered the top quark in 1995.

The top quark probably won't cure the common cold or help us get more miles to the gallon. But, like the discoveries that have come before, it will help make our universe more understandable.

Accelerating technology

As each generation of particle accelerators builds on the accomplishments of the previous one, it forces up the level of technology. Each new generation has systems that are the biggest, fastest, and most advanced of their kind. These then become the industry standard; they form the basis for new commercial ventures and for the next generation of accelerators. From the Tevatron accelerator alone came the largest helium cryogenic system ever built, the largest and most complex vacuum system of its time, a control system that was a pioneer in the use of large-scale distributed intelligence, and what is still the largest system of superconducting magnets. All of these are now standard, allowing us not only to build better particle accelerators but to pursue designs for such things as maglev trains, widely distributed control systems, large superconducting power transmission lines and energy storage as realistic possibilities, no longer merely dreams.

Superconductivity-- a new industry

Building Fermilab's Tevatron, the world's first superconducting synchrotron accelerator, helped lay the foundation for a new industry in the United States--superconducting technology. This power-conserving technology has applications in the fields of energy, transportation, medicine, the environment and electronics. In the words of the late Robert Marsh of Oregon's Teledyne Wah Chang, the world's largest supplier of superconducting alloys, "Every program in superconductivity that there is today owes itself in some measure to the fact that Fermilab built the Tevatron and it worked."

What good is high-energy physics?

The discovery of the top quark probably won't cure the common cold or help us get more miles to the gallon. But like the discoveries that have come before, it will help make our universe more understandable. Like those discoveries, it will take us another step forward in our knowledge of the nature of nature--knowledge that will change not only our understanding of the world, but our world itself.

Background Material on the Discovery of the Top Quark