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dimensions of particle physics

dimensions of particle physics

A joint Fermilab/SLAC publication


SLAC at 50

September 05, 2012

SLAC at 50

SLAC National Accelerator Laboratory honors its five-decade history as it forges ahead into new areas of scientific research.

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In the early 1960s, a 2.5-mile-long strip of land in the rolling hills west of Stanford University was transformed into fertile ground for physicists’ dreams: the longest linear accelerator in the world, built for studies of the mysterious subatomic realm. 

In late August, more than 1000 people gathered at SLAC National Accelerator Laboratory to celebrate 50 years of scientific successes made possible by that accelerator and the ones that followed. 

At the event, SLAC Director Persis Drell told gathered employees, former employees and university, government and scientific leaders that the celebration was “not just about honoring our very distinguished, great past but about celebrating where we are today and the contributions that so many of you have made to the history of this laboratory. Today is about looking to the future of this laboratory and the discoveries yet to be made.” 

The celebration, which included a day-long scientific symposium, speeches, tours and a barbecue, included both tribute to the momentous discoveries made possible by the minds and machines at SLAC and a look ahead at the lab's continuing evolution and growth into new frontiers of scientific research.

A history of discovery

The linear accelerator project, approved by Congress in 1961 and dubbed “Project M” for “Monster” by the scientists who conceived it, was a supersized version of a succession of smaller accelerators built and operated at Stanford University. 

Gregory Loew, who began his 50-year career with the laboratory in 1958, said, “If you asked me when I joined the project what we were going to discover with this accelerator, I didn’t know. But I fully trusted that something new and exciting was going to be found.”

It was. 

Soon after the new accelerator reached full operation, a research team including SLAC and Massachusetts Institute of Technology physicists used the electron beam to discover that protons in the atomic nucleus were composed of smaller entities called quarks. That research led to the 1990 Nobel Prize in Physics, shared by SLAC's Richard Taylor and MIT’s Jerome I. Friedman and Henry Kendall.

A dozen years after SLAC’s founding, researchers again struck physics gold with discoveries that were made possible by another major technical feat—the addition of the Stanford Positron Electron Asymmetric Ring. Scientists used SPEAR to bring circling beams of electrons and positrons from the linear accelerator into continuous head-on collisions.

In what became known as the “November Revolution” in particle physics, experimental teams led by physicists Burton Richter at SLAC and Samuel Chao Chung Ting at Brookhaven National Laboratory announced their independent discoveries of the J/psi particle, which consists of a paired charm quark and anti-charm quark, in 1974. They received the Nobel Prize in Physics for this work in 1976.

In 1975, SLAC physicist Martin Perl announced the discovery of the tau lepton, a heavy relative of the electron and the first of a new family of fundamental building blocks, for which he shared the Nobel Prize in Physics in 1995.

And in the early 2000s, researchers on the BaBar experiment, which created huge numbers of particles called B mesons and their antimatter counterparts, anti-Bs, and their Japanese colleagues at KEK’s Belle experiment announced evidence supporting the idea that matter and antimatter behave in slightly different ways (a mismatch called charge-parity violation).

A new field is born

New research areas and projects at SLAC have often evolved as the offspring of the original linear accelerator and storage rings. 

Stanford and SLAC researchers quickly recognized that radiation generated by particles circling in SPEAR, while considered a nuisance to the collider experiments, could be extracted from the ring and used for other types of research. They developed this “synchrotron radiation,” which came in beams of X-ray and ultraviolet light, as a powerful scientific tool for exploring samples at a molecular scale. 

This early research blossomed as the Stanford Synchrotron Radiation Project, a set of five experimental stations that opened to visiting researchers in 1974. Its modernized descendant, the Stanford Synchrotron Radiation Lightsource, now supports 30 experimental stations and about 2000 visiting researchers a year. 

Roger D. Kornberg, professor of structural biology at Stanford, received the Nobel Prize in chemistry in 2006 for work detailing how the genetic code in DNA is read and converted into a message that directs protein synthesis. Key aspects of that research were carried out at SSRL. 

Pushing the limits

Building on its strong light-source and accelerator knowhow, SLAC now uses sections of the linear accelerator to drive two cutting-edge facilities: the FACET test bed for next-generation accelerator technologies and the Linac Coherent Light Source, the world's most powerful X-ray free-electron laser. An expansion of LCLS, dubbed LCLS-II, is slated to begin construction next year. 

The laboratory also operates vital programs in astrophysics, materials and environmental sciences, biology, chemistry and alternative energy research. Just as they have since the 1960s, scientists stream by the thousands to use SLAC facilities for a broad spectrum of experiments.

During the 50th anniversary symposium, speakers detailed emerging research frontiers that SLAC is well positioned to investigate, including the elusive ingredients of dark matter, and outlined opportunities for merging multiple disciplines, from cosmology to particle physics and theoretical physics, in pursuit of common scientific aims. 

Innovate or die

The late Wolfgang “Pief” Panofsky, who served as the lab's first director from 1961 to 1984, often noted that big science is powered by a ready supply of good ideas. He referred to this as the "innovate or die" syndrome.

In 1983, Panofsky wrote that he was often asked, “How long will SLAC live?”

His answer to the question holds true today: About 10 to 15 years, unless somebody has a good idea. “As it turns out, somebody always has had a good idea which was exploited and which has led to a new lease on life for the laboratory,” he said.

At SLAC’s 50th anniversary celebration, Stanford University President John Hennessy agreed: “For five decades, SLAC—its directors, researchers and staff—have charted new paths, advancing the frontiers of both theoretical and applied knowledge while finding new ways to collaborate and innovate. SLAC has served as a magnet for researchers around the world; it is this coming together of talented and driven researchers that has made SLAC such an incredible source for such great advances in science.”

Secretary of Energy Steven Chu, a Nobel Prize-winning former Stanford University professor who served as director of Lawrence Berkeley National Laboratory until his 2009 call to lead the Department of Energy, summed it up:

“I can’t pretend to know what will happen in the next 50 years, and if we did, that would be very disappointing,” Chu said. “We can count on the fact that there will be a whole lot of surprises.” 

SLAC at 50: “Creating the Future”

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