Thomas Clegg: a straight shooter in a spin zone
A friend described Thomas Clegg as a whirling dervish of intellectual energy. Spend just a few hours with him inside the little universe called the Triangle Universities Nuclear Laboratory (TUNL), and it is easy to see the description fits.
And maybe even better than the friend could have known.
Here in this lab, much of the science is all about spin. If you don’t believe it, consider the telling data on the license plate of Clegg’s Volvo. It reads: SPINUP. He was going to have it read SPINDOWN, Clegg said, but it wouldn’t fit on the plate. More about that later.
He is a thin man, quick with a burst of laughter or a smile, and he exudes so much energy you almost want to stick a “High Voltage” warning sign on him so people can stay safely back.
Weekdays, you are likely to spot Clegg on the road between Chapel Hill and Durham, as Clegg splits time between the classes he teachers at Carolina and the laboratory he helped develop on the campus at Duke University.
That’s another thing Clegg is pretty good at — handling all the many things on his plate. And that’s one of the reasons he was honored this year with a C. Knox Massey Distinguished Service Award.
One afternoon, as he drove to the lab with a visitor, he cradled a diet soda in his lap and began telling the story of his life — and the lab that has been the center of it ever since he arrived at Carolina more than three decades ago.
He had three hours to try to squeeze it all in, and not a minute to waste.
A college boy with a little country thrown in
There seems little doubt now that Clegg was destined for a career on a college campus, considering the fact he practically grew up on one.
His father was a sociologist and anthropologist at Emory University in Atlanta. Born Jan. 6, 1940, Thomas was the first of three boys. Clegg’s father was too old to go off to fight in World War II, but he ended up getting drafted anyway — into university administration as an assistant dean. When soldiers started coming home after the war, he was put in charge of the GI program, and by the time Clegg was old enough to go to college his father had been Emory’s admissions officer for several years.
“I got in,” Clegg cackled.
His interest in science, he figures, came from his mother. “My mother is probably where I got my genes for interest in science,” Clegg said. She was a chemist who taught high school chemistry in Atlanta before she started rearing her three boys.
Thomas was 12 when she died; his two brothers, 9 and 6.
And their father suddenly had to figure out how to go to work and tend his boys on his own. As it turned out, his job held the solution. “As the director of admissions, he had access to all the files of all the incoming freshmen at Emory,” Clegg said. “He looked there and found the brightest, neediest freshman he could and offered this guy free room and board if he would help take care of this unruly horde at home.”
During the summer months, their father sent his three boys off to his hometown of Social Circle, Ga., to stay with aunts and uncles. Once there, they were put to work in the fields, harvesting tobacco or hay.
In summer, he and his brothers ended up at the fishing pond after they quit the fields.
But in school, the field Clegg migrated to was physics. “I just liked it,” Clegg said. “I like understanding how things work.”
And nuclear physics, in particular, was considered the exciting new field — the way genomics is today.
And when he arrived at Rice University in Houston in the fall of 1961, waiting for him was a state-of-the-art nuclear physics laboratory.
He earned his master’s degree in 1963, his Ph.D. in 1965 at Rice, then set off for the University of Wisconsin at Madison. It was there that he met Janet, a graduate student in French from Rhode Island who would become his wife. They married in Madison in August 1968, one week before they left for Chapel Hill. Janet would end up teaching French at Durham Academy and later Chapel Hill High School.
When Clegg joined Carolina’s physics department, he was not yet 30 and on the cusp of an exciting opportunity to help set up a premier laboratory similar to the one he had left in Wisconsin.
At the time, leaders from Duke, Carolina and N.C. State University had convinced officials at what was then the Atomic Energy Commission (now the Department of Energy) that when it came to research in nuclear physics, funding one lab that serves three universities made sound fiscal sense. The federal government literally has bought that argument ever since through its continued funding of the TUNL lab.
And the lab is one of the biggest reasons Clegg never saw a reason to go anywhere else. If you are a physicist doing what he does, he said, there is no better place in the country to do it than there. And the lab is as good as it is because there are so many talented people sharing it.
The Volvo with the special plate zipped into a Duke parking lot, which does double duty as the roof of the lab directly underneath.
Clegg proved to be a patient teacher. After making an especially critical point, he often said “All right?” to hammer the point home.
To understand what a nuclear physicist does, Clegg explained, you first have to know what a nucleus is.
A nucleus is simply the tightly packed core of any atom such as hydrogen or carbon or any other element in the periodic table. Within each nucleus are positively charged particles called protons and neutrons that have no charge. Surrounding each nucleus is a swirling cloud of negatively charged electrons.
Most people who have been exposed to science understand that like charges repel and opposite charges attract. And that raises the question that still has physicists scratching their heads.
“If positive charges repel each other, why the hell don’t nuclei just fly apart? What holds them together? There’s a force there holding the nuclei together that is much stronger than the electrostatic force of repulsion between the two charges. That’s the fundamental thing that we are trying to understand and figure out — the nature of that force, what its properties are, what its range is, how far apart can the nuclei be before they don’t feel each other anymore.”
What makes the task of answering these questions so enormous is the fact that nuclei are so tiny.
If you want to know what’s going on inside a watch, you have to take it apart with a screwdriver. Or, if you don’t have a screwdriver small enough, you can throw it on the ground and see what kind of shrapnel comes out.
But you can’t throw a nucleus on the floor and see how it shatters like you can a watch. And there’s where Clegg and the lab come in.
The devices in the lab, including the one that Clegg helped develop more than a decade ago, are more like sledgehammers or guns that splinter the nuclei into shrapnel.
Within the shrapnel, they know, are the clues that will help them figure out what makes the nuclei tick.
The three-hour tour
How do you tell the story of three decades of work in three hours? The way Clegg does everything — in a hurry.
He began in the control room, which is packed with so many gauges and knobs and dials and meters that you would think it could run a nuclear power plant. But this laboratory, unlike a nuclear power plant, makes nuclear reactions one-by-one rather than in spontaneous chain reactions that produce enormous and potentially destructive amounts of energy.
Opposite the panel of gauges are computers where scientists read and interpret the results of their experiments. Behind the computers is a tangle of cables that connect the computers to the various target apparatus and bring in the electrical pulses of the “shrapnel” left when those particle beams hit their targets and explode.
The laboratory itself could best be described as an Erector Set on steroids, filled with metal and magnets and electronic gadgets of all shapes and sizes. And at the center is the main accelerator, a cylinder about 30 feet long and 15 feet in diameter that glows a beautiful bright red when turned on.
The generic name for the device is an electrostatic accelerator, although it is named for the man who invented it, Dutch physicist Van de Graaff.
Inside the accelerator tank is a positively charged silver dome that negatively charged particles are shot toward. Because they are opposite charges the dome attracts, and the particles accelerate toward it. Once they hit the dome, the negative particles pass through a high-voltage terminal inside that is nothing more than a thin foil. Passing through the foil, the particles are stripped of their electrons and take on a positive charge. And as positively charged particles they are now repelled from the positively charged dome and speed away from it ever faster.
The particles exit the cylinder and enter a vacuum system of copper pipes that could be compared to a network of guns, each set up to shoot a particle beam toward an intended target.
Yes, the pipes could be compared to the barrel of a gun, Clegg said, “but it is a complicated barrel.”
A bullet spins through a gun barrel the way a football spirals through the air so it can go farther in a straight line. But when you fire beams instead of bullets, they have to be steered through empty space inside this tube with the help of strategically placed magnets and high-powered electricity.
In 1986, Clegg drew the assignment of leading the team that built one of these so-called guns capable of producing what Clegg called “intense spin-polarized ion beams.”
This is even more complicated stuff, but Clegg plunged in with a complete explanation of the magnetic forces that made it all work. This gadget, after all, represents the core piece of his long career and holds the answer to the riddle on his license plate.
“In the case of the bullet, you’ve got a slug of lead and it’s spinning, but spin in the case of nuclear physics is different,” Clegg said. “The protons and neutrons which are the constituents in nuclei are little magnets. Now, that’s not the precise scientific view but they can behave like little magnets. Their magnetism comes in part from the fact that they have angular momentum — you can say they are spinning.”
So what Clegg and his colleagues set out to do was design a device capable of controlling the spin by producing ion beams that could be flipped, or polarized, in whatever way a particular experiment called for.
“We can make magnets — little nuclei magnets in the quantitative sense — whose north end is up and south end is down, or north end is down and south end is up. Or we can make all the particles in the beam have the same orientation, which means that our beam has been polarized. That’s what we mean by spin polarization.”
And thus the SPINUP license plate.
The device took three years to design and build and test, an $800,000 grant from the Department of Energy and the equivalent of what Clegg called “25 person years.” What’s that? He paused. “That’s the P.C. version of man years,” he laughed before turning serious about the limited role he had in making it all happen.
“It was successful not so much because of me, but because of a whole bunch of people who were clever worked hard at it, all right?”
A positively charged force
Closing in on 3 p.m., Clegg was just getting around to eating lunch. He pulled a sandwich out of a bag. He already had drunk his usual diet soda on the drive over.
“I’m sorry,” he said, as he talked and chewed and glanced down at his watch. Clegg is the kind of guy who can eat a sandwich and still talk with his mind full of too many things left to say. There was still so much to go over and tell, but he had only 15 minutes to spare before he had to start heading back to Chapel Hill for a 4 p.m. staff meeting. Can’t be late, he said.
He summed up as best he could.
His work at TUNL is not only the focal point of his work, it was the cutting stone that shaped the way he sees things and the way he works with others. During his first 20 years at Carolina, he kept his head down and did his research and taught his classes.
But the lab changed him over time, forced him to pull off the blinders and look up at what other people did, too. Then, in 1989, he was named chair of the Department of Physics and Astronomy and part of his job became paying attention to what everybody else was doing. To his surprise and delight, he found himself enjoying it more than he had imagined he could.
The Massey citation mentioned his many accomplishments during the 10-and-a-half years he served as department chair, including his work establishing the University’s SOAR project now developing a Southern Hemisphere astronomical observatory. Much of the work going on at the TUNL lab now has to do with the particle theory involved in the study of stars as well.
The award cited his multiple committee activities over the past decade associated with the University’s land-use and master planning efforts. He chaired the 1994-95 committee charged with determining the best uses for Horace Williams and Mason Farm, and his involvement with Horace Williams is only really beginning. He also helped lead the task force that developed the first plans for the new Science Complex.
David Godschalk, a professor with the Department of City and Regional Planning, described Clegg as a model collaborator. The two men worked together in helping to develop and promote the new development plan for campus that the Chapel Hill town board passed last month.
“Tom listens well and responds effectively to a wide range of people and issues,” Godschalk said. “I have watched him in action on the Buildings and Grounds Committee for a number of years, and I am consistently impressed with his knowledge of the University and his sensitivity to proposals affecting its environment.”
Clegg doesn’t credit himself for what he has done, but instead credits his colleagues and, believe it or not, his field of study. “I do think that physics as a discipline provides a set of skills that is good far beyond the realm of physics — teambuilding, problem-solving, analytical skills — they are all important.
“I think physicists, especially experimentalists who look at problems, learn that you tackle problems by breaking them down into little pieces. You start with what you understand, then try to pose for yourself the question, `OK, what is it that I have to solve here?’ You figure out a set of goals you want to work toward, then you figure out what you need to do to get there.”
Clegg has managed, in his spare time, to squeeze in a life around his career.
Since 1977, his wife’s mother, “Me-mere,” has lived in a separate apartment in their house in Chapel Hill. When their son, John, was a boy, she served as a wonderful baby sitter. Now, at the age of 92, they are able to provide support for her when she needs it.
John lives in Boston now with his wife and their first child, a girl, who was born in August. “Our Thanksgiving holiday will be a big deal since it will be the first time I will get to see her,” Clegg said.
What does he do to unwind? He runs, of course, three miles every morning before work, four to five miles at a time on weekends. It has kept him in shape all these years, he said, and he will keep doing it for as long as he is able. And the same goes with his teaching.
At the age of 61, he may be getting older, but his students have not allowed the subject to grow old to him. “One of the nicest things about being in a university is that young people keep coming through the door each year,” Clegg said.
At the start of every class, a hand will always shoot up with the comment, “But I don’t quite understand.”
“Now you’ve got to think hard about what they don’t understand, how to explain it to them better. I find it a challenge, and I try to do it as well as possible.”
And that’s no spin, all right?
Originally published by University Gazette: Nov. 21, 2001