Driving south on Interstate 280 from San Francisco toward Silicon Valley, you soon pass above a long, low structure stretching off to the west for more than a mile into the foothills of the Santa Cruz Mountains. One of the longest buildings on the surface of the Earth, this curious feature is the "klystron gallery" of the Stanford Linear Accelerator — by far the world’s largest electron microscope. With a good amateur telescope, you could see it from the Moon.

Ever since this accelerator began operations in the mid-sixties, the Stanford Linear Accelerator Center (SLAC) has been generating intense, energetic beams of electrons and photons for scientific research on the structure of matter. Physicists using its research facilities have won three Nobel prizes for discoveries of quarks and an elementary particle called the tau lepton, which are recognized today as fundamental building blocks of matter.

Other scientists have employed SLAC’s ultrabright X-ray beams to determine detailed structures of important biological molecules such as RNA polymerase, a key enzyme that governs how genes are transcribed into proteins. Still others examine the behavior of semiconductors, superconductors, catalysts and an endless variety of advanced materials that are increasingly essential for today’s high-tech industries.

SLAC is a national laboratory operated by Stanford University on behalf of the U.S. Department of Energy (DOE), which supports nearly all its operations. The National Institutes of Health and the National Science Foundation provide added funding for specific equipment and experiments. Use of SLAC facilities is open to qualified researchers from all across the country and around the world. About 3,000 such "users" come to the laboratory each year from more than 20 nations to conduct research in groups ranging from a few scientists to hundreds of them. In addition, SLAC has a staff of over 1,400 highly qualified individuals living in the Bay Area; more than 300 are scientists actively involved in ongoing research. The results of all research performed at the laboratory are published openly in scientific and technical journals; no classified research occurs here.

The principal focus of SLAC research is the field of particle physics. High-energy beams of subatomic particles collide with stationary targets or with each other; these collisions provide insights into the behavior of matter and energy at extremely tiny distances or under very violent conditions that previously occurred only during the Big Bang birth of the Universe. Stanford University and SLAC have pioneered the acceleration and use of electron beams for this research; the laboratory currently generates the highest-energy electron beams found anywhere in the world.

During the past two decades, SLAC physicists developed a completely new kind of particle accelerator called a "linear collider," in which beams of electrons smash into their antimatter counterparts, known as positrons, after having been boosted to high energy in a single pass down the linear accelerator. Working with colleagues from other laboratories in Europe, Japan and the United States, they are designing a next-generation machine dubbed the Next Linear Collider, which will stretch about twenty miles and serve the international scientific community.

Cutting-edge research on the behavior and structure of matter at atomic and molecular levels occurs at another major SLAC facility, the Stanford Synchrotron Radiation Laboratory (SSRL). There physicists generate extremely intense X-ray beams -- millions of times brighter than conventional X-ray tubes produce -- by circulating high-energy electrons through magnet arrays. Each year, about 1,600 scientists from many disciplines use this radiation to conduct research in such areas as designing new drugs, developing advanced information technologies (e.g., flat-panel computer displays and high-density microchips), and the environmental remediation of contaminated sites. Since its inception in the mid-1970s, SSRL has pioneered this field of synchrotron-radiation research, developing instruments and techniques commonly used today in nearly 50 such laboratories around the world.

Today SLAC is poised to begin building a next-generation facility, called the Linac Coherent Light Source, that will help roll back the frontiers of X-ray research. Electrons accelerated in the final third of the linear accelerator will be compressed and directed through a special magnet array to produce laser-like X-ray beams of unparalleled brilliance. This unique instrument will open remarkable new avenues of scientific research on such topics as ultrafast chemical reactions.

SLAC has also been moving aggressively into the growing field of particle astrophysics and cosmology. (In fact, the theory of inflation, which put the "bang" in the Big Bang, was conceived here in 1980 by a postdoctoral researcher.) Aided by scientists from universities and laboratories in Europe, Japan and the United States, SLAC physicists are designing and building the Gamma-ray Large Area Space Telescope, a sophisticated detector of energetic photons now scheduled for launch into Earth orbit in 2006. Jointly sponsored by DOE and the National Aeronautics and Space Administration (plus foreign scientific agencies), this satellite will observe outbursts of gamma rays from black holes and other exotic astrophysical sources.

SLAC is a world leader in the development of advanced particle acceleration techniques and high-power klystrons -- devices that generate the microwaves for accelerating electrons. Invented at Stanford in 1937, klystrons are also used to power radar arrays and for medical accelerators employed in cancer therapy. For decades, SLAC has shared people, designs and ideas in a symbiotic relationship with industry that has steadily advanced klystron technology. The manufacture of medical accelerators is now a billion-dollar industry; every day, about a hundred thousand people receive cancer treatment on them in the United States alone. And a software program developed by a SLAC scientist to simulate showers of subatomic particles is now used by hundreds of hospitals throughout the world to plan radiation dosages for cancer therapy.

Computers and telecommunications are other areas where SLAC research has strongly affected Bay Area and U.S. economies. In December 1991, the World Wide Web landed at SLAC, which established the very first Web site in North America. One of the earliest Web browsers was developed here by a physicist to communicate the reams of documents and data typically produced in high-energy physics. The fact that the Bay Area is a major center of Web site and software development can no doubt be traced to its Stanford origins.

Scientific education is another of SLAC’s important goals, as is dissemination of knowledge about its scientific activities to the general public. More than 10,000 people annually visit and take tours of the laboratory. The thousands of students who have come here to participate in advanced research have worked at the side of some of the best scientists on the planet, exploring the frontiers of diverse fields. They return to universities across the country and around the globe — or assume positions in business or government — with a much better understanding of what it means to do forefront research. They also carry back with them lasting memories of the San Francisco Bay Area as one of the world’s leading centers for science and technology.