DOCTORAL FISSION

by Monte Basgall

TUNL vision: inside the glass supporting column of the high-voltage terminal of the "tandem" Van de Graaff accelerator
Photo: Duke University Photography

Nuclear Reactions on Campus: "We thought in 1950 that nuclear physics was an important discipline and we got into it early"

he roots of the Triangle Universities Nuclear Laboratory, the Duke-based facility that trained Los Alamos Nuclear Lab director John Browne Ph.D. '69, can be traced back to the first controlled nuclear chain reaction, which took place at the University of Chicago's Stagg Field.

That epic 1942 experiment, which ushered in both nuclear weapons and nuclear power plants, was led by Enrico Fermi with plenty of input from co-researchers like Henry Newson, the man who later brought nuclear physics to Duke. Then a member of the World War II Manhattan Project, which developed the atom bomb, Newson went on to the top-secret research facilities at Oak Ridge, Tennessee, where he helped supervise the first loading of the graphite reactor there.

Newsom then went to Hanford Engineering Works in the state of Washington. During a famous graveyard shift in September 1944, he performed some critical neutron measurements that explained why a crucial reactor had stopped working. By 1945, he was a group leader at Los Alamos Scientific Laboratory in New Mexico, where the first atomic bomb was put together. Later he became chief physicist at Oak Ridge National Laboratory. Newson left government service in 1948 to spend the next thirty years at Duke. He started the Nuclear Structures Laboratory to begin painstaking measurements designed to resolve many lingering questions around nuclei, the centers of atoms.

Feeding the "tandem": particle sources delivery systems that lead to the accelerator, top center
Photo: Duke University Photograpy

To study objects only about one infinitesimal quadrillionth of a meter wide, scientists must lob equally small or smaller projectiles at them and see what happens. To do that, Newson brought the first commercial Van de Graaff accelerator to the new Duke lab in 1951. Named for their inventor, U.S. physicist Robert Jemison Van de Graaff, these devices borrow on the dramatic principle nature uses to generate lightning. A rapidly moving belt builds up huge electric fields within a bulbous terminal, and those millions of volts of stored charge can then accelerate charged particles away at high speeds.

Duke's first 4-million-electron-volt Van de Graaff was of the same type installed at Brookhaven National Laboratory on Long Island. Newson and his co-experimenters at Duke would use it in the early days to learn more about how neutrons, the same particles whose chain reactions make uranium go "critical," interact in nuclei of various atomic elements.

It was a heady thing for a small university physics department to attempt, but Newson was no small thinker. "We thought in 1950 that nuclear physics was an important discipline and we got into it early," recalls Edward Bilpuch, the Henry W. Newson Professor Emeritus at Duke. Bipluch came to the lab in 1956 as a research associate and stayed. "Most of our competitors were places like Brookhaven, Oak Ridge, Lawrence Livermore National Laboratory, and Argon National Laboratory. We carved a niche for ourselves in this important field."

At the American Physical Society's 1954 meeting in New York City, an entire session was devoted to papers from Duke. Besides the longevity of its staff, another immediately-apparent trait of the Nuclear Structures lab was the quality of its graduate students. The very first doctorate there was awarded to John Gibbons Ph.D. '54, who went on to become President Clinton's science adviser. George Keyworth Ph.D. '68 served the same role in the Reagan administration.

Between 1951 and 1958 the Duke lab's staff built their own neutron detection devices to study all the natural elements-from hydrogen to uranium. The goal was "to try to understand how nature put these nuclei together, why nuclei exist, and why they stay so stable," says Bilpuch. By 1964, the lab was ready for a second, bigger "tandem" Van de Graaff, essentially two separate accelerators running back to back. With a further power boost from a cyclotron injector, it could reach energies as high as 30 million electron volts.

The then-U.S. Atomic Energy Commission (AEC), which was superseded by the U.S. Department of Energy (DOE) in 1977, agreed to fund the bigger machine at Duke to learn more about nuclei of "light elements" such as Lithium 6 and Lithium 7, as well as those for atomic elements in stainless steel. The reason was hopes for developing a controlled nuclear fusion program.

But with the bigger machine also came bigger responsibilities. "We realized that to run it efficiently would take more faculty and staff than Duke had," notes Bilpuch, who became TUNL director after Newson died in 1978. "Then the idea occurred to us to form a joint regional laboratory with other participating faculty from the University of North Carolina at Chapel Hill and North Carolina State University in Raleigh."

Duke provided four acres to build a separate $1.5-million building near its existing Physics Building. And the North Carolina Board of Science and Technology, National Science Foundation, and U.S. Office of Education all provided funding.

As a result, in 1965 the old Nuclear Structures Laboratory was officially reborn there as the Triangle Universities Nuclear Laboratory, or TUNL. Today, it's a base of operations for seventeen core faculty from the major Research Triangle institutions, plus more than twenty other staff researchers and technicians, thirty graduate students, and many visiting investigators from around the world. All work in a three-story radiation-shielded concrete building anchored to the granite bedrock for vibration control.

Since 1950, TUNL and its predecessor have received about $110 million (estimated in 1996 dollars) in research support from its core funding agencies, the old AEC, and the current DOE. It has also become a world center for experiments with polarized ions, used to study questions surrounding the invariance of nuclear reactions, as well as problems in astrophysics.

New projects include collaborating with Duke's nearby Free-Electron Laser Laboratory to develop and use a powerful and unique new source of gamma rays, and working with the Japanese on a major neutrino detection project being built inside a mountain.

TUNL has now graduated 207 Ph.D.s. Roughly one-third end up in government labs, another third in industry, and the rest on university faculties. Browne is one of so many that end up at Los Alamos that it's called the "TUNL of the West."

Why do its graduates do so well? One big reason is their "hands-on training," said Werner Tornow, TUNL's current director, who himself was attracted from Germany to study neutron physics. "If you do a Ph.D. here, you are working within a small group and you are responsible from the very beginning of an experiment to the very end. If you're responsible for everything, you have to learn everything."