Physicist's work changes modern view of the proton (The Virginian-Pilot)

Jefferson Lab in the News

Physicist's work changes modern view of the proton

NORFOLK — Her father wanted her to follow his path as a Sanskrit teacher.

Instead, Vina A. Punjabi became a physicist whose research has helped revolutionize the modern view of a fundamental atomic particle — the proton.

The Norfolk State University professor spoke at a news conference in Philadelphia on Saturday, at the annual meeting of the American Physical Society, about her work, which has even led scientists to redraw the shape of the proton.

Her research "definitely has changed the way we think about the proton," said Gerald A. Miller, a professor of physics at the University of Washington in Seattle, who admits being surprised by the results. "It's not the final word, but it's a fairly significant step."

The proton is the positively charged particle in the nucleus of an atom. It is one millionth of a billionth of a meter long.

Orbiting the nucleus is a cloud of negatively charged electrons. "The atom is held together because those two charges are operating and producing a force between then," Punjabi said.

Working with three other researchers at the Jefferson Lab in Newport News, Punjabi bombarded liquid hydrogen — packed in a container the size of a beer can and cooled to minus 420 degrees Fahrenheit — with a stream of electrons moving at the speed of light.

That allowed the team to get an up-close look at the inner workings of the recoiling protons.

Their findings are weighted with phrases such as "electric form factors" and "random polarization orientation."

In simpler terms, they have shown that the electrical charge and the magnetic strength decrease the farther you go from the center. But the electrical charge decreases more slowly than does the magnetic strength, contradicting previous notions.

That, in turn, has elongated the contemporary portrait of the proton. No longer considered a sphere, it probably looks more like a football or egg, Punjabi said. Forget those circles in science textbooks.

The implications are too early to predict, Punjabi said, though the work underscores the importance of the spins carried by quarks and gluons — components of the proton whose workings remain a mystery to physicists.

"It's a real soup," said Punjabi's main partner in the research, Charles F. Perdrisat, a physics professor at the College of William and Mary. "We still don't have a full understanding of the proton. A lot of people are working on it right now, in part stimulated by the results of this experiment, but the mathematics is very hard."

The other researchers are Mark Jones, a scientist at the Jefferson Lab, and Edward Brash, a professor at the University of Regina in Canada. All four are studying the atom.

Punjabi grew up in India, where she received her bachelor's and master's degrees. But not in the field her father expected.

"In India, the son is supposed to go into science," she said. "The daughter is supposed to go into the arts." But she was interested in science.

Her brother suggested medicine, but she rejected that, too, after a few frog dissections in college — "I did not like blood and gore."

Punjabi came to the United States in 1979 and received her doctorate in physics in 1986 from the College of William and Mary.

She has been at NSU since 1988, splitting her time between the Jefferson Lab and a cramped office in a trailer next to Norfolk State's science building. That's OK with her: She has what she needs most — her computer.

Punjabi loves interacting with students, as well as with atomic particles. "It is very, very important to me to train young minds," she said. And to spread the gospel about her field.

"I try to tell them to do physics," she said. "It is much more interesting than mathematics or computer science."

Henry Lovelace, a sophomore physics major, said: "It seems like she really cares about the students. If you don't understand something, she'll give you a lot of help."

And her high-powered research? "It proves she knows what she's talking about," Lovelace said.