The News about Neutrinos
Geralyn “Sam” Zeller (WCAS94, G02), a recent graduate student in physics, has made some startling discoveries in the world of subatomic physics.
For two years Geralyn “Sam” Zeller (WCAS94, G02) — until last spring a Northwestern graduate student in physics — has been watching autocross, a vehicular obstacle course, in the Chicago area on weekends in cone-filled parking lots and on tracks. But lately Zeller, driving her Subaru WRX, has begun entering races herself.
“I’m just waiting for the day when I actually win and can rub it in … that these dudes were beaten by a chick in a station wagon,” she says.
When Zeller, who hails from Glenview, Ill., is not engaged in fast-paced thrill racing, she’s uncovering the secrets of the even faster neutrino, a universal particle that’s so small it’s never been seen.
During the past few years Zeller, who’s been called Sam since childhood, used her knowledge about neutrinos to help discover a flaw in a theoretical picture that had explained the workings of the universe for the last 30 years.
Zeller does her research on neutrinos at Fermilab, in Batavia, Ill., home to the world’s most powerful particle accelerator. Today she finds it all very exciting, though no one would have guessed that through most of high school Zeller hated science. But a day trip to Fermilab in her 12th-grade physics class changed her mind.
“We passed by the main control room, and there were tons of people working frantically inside,” she says of the field trip. “One of the phone operators looked particularly frazzled, with a receiver at each ear. I thought this looked like a really cool place to be.”
Zeller, now a postdoctoral fellow in high-energy physics with Columbia University, was also swept up that day into the frantic pace of particle physics.
“It was fascinating how these particles can whip around and then cross at the width of a human hair,” she says. “It still blows my mind.”
Zeller started working at Fermilab when she was an undergraduate at Northwestern. “I was pulling cables and doing a lot of hardware work, helping to put together a huge iron toroid spectrometer,” she says of her undergraduate employment. “They needed a skinny person with long arms to slide under the detectors. That was me.”
Since then Zeller’s work has gotten a lot less physical and involves a lot more physics. Her graduate thesis experiment was called Neutrinos at the Tevatron (or NuTeV). “In NuTeV we discovered that forces don’t act on neutrinos exactly as we thought,” Zeller says of her experiment, conducted with her adviser, Heidi Schellman, Northwestern professor of physics and astronomy, and Kevin McFarland-Porter of the University of Rochester. Specifically, they found that one of these forces acts on neutrinos with less strength than it exerts on other particles, a major and surprising discovery.
Her newest project, MiniBooNE (Booster Neutrino Experiment), began running in August. The experiment, which extends over several years, will determine whether neutrinos oscillate by shooting them into a 1.4-million-gallon steel globe of mineral oil buried under the Fermilab campus. More than 2,000 phototubes inside the oil will detect possible particle oscillations.
“Since we can’t ‘see’ neutrinos, all we can detect are the products of their interactions in the mineral oil, namely,charged particles that produce shockwaves of light,” Zeller says.
If the particles oscillate, MiniBooNE will prove that neutrinos have mass. “If neutrinos have mass in this region of oscillation space, then we don’t understand what the hell is going on,” Zeller says. “Neutrinos are at the cutting edge of the unknown right now. With a little luck, they might help us create a better standard model, but neutrinos continually trick us.”
Fortunately, whatever the results are for Zeller’s latest experiment, she will still enjoy a perk of particle physics — world travel.
“I’ve already been to France three times,” she says. “Physicists tend to pick very agreeable locations for conferences.”
One place that intrigues her is a neutrino experimental site being proposed for Japan. “It would be pretty cool to live there,” she says.
Yet no matter where the science takes her, Zeller hopes to continue studying neutrinos. “I don’t really care about location,” she says. “I’ll go wherever the physics is interesting.”
Gregory Presto (J04)