Helen Hanson likes it cold—negative 442 degrees Fahrenheit, to be exact.
That’s the temperature at which she performs her doctoral research in Physics: it’s when a crystal of Niobium becomes a superconductor, which means the element goes from being a metal that conducts electricity to one that conducts it so efficiently that no energy is lost. “That is a very special change,” Hanson says. “It’s big, comparable to water changing from a liquid to a solid.”
Hanson likes to explain superconductors. In most materials, she says, especially metals, atoms are arranged very neatly, and they vibrate back and forth. At warm temperatures, they have lots of energy; at cold temperatures they grow more sluggish. At really, really cold temperatures, the atoms stop vibrating altogether, and paths open up between them for electrons to move through.
For Hanson’s project, which is funded by the U.S. Department of Energy, a cylindrical Niobium crystal about a centimeter long is cooled in a tank of liquid helium. Hanson bombards the crystal with a beam of neutrons, creating what she calls a “mini-explosion.” Observing how the particles diffract and scatter allows her to draw conclusions about the internal structure of the Niobium sample. “If we understand this simple and how it works, then we remove a lot of the guesswork about superconductors.”
What’s so special about superconductors? “The biggest possible application of this research is to develop a palpable solution to the energy crisis,” Hanson says. But scientists typically don’t focus on biggest possible applications, and Hanson is no exception; she zeroes in on Niobium crystals the way a kid pokes an anthill to see what happens. “I love my research,” she says. “I like understanding systems inside other systems. There is so much powerful thought going into understanding this one simple element, and so many levels of detail, yet the basic concepts relate more broadly to ideas in biology, anthropology, political science and more.”
Hanson almost became an engineer instead of a physicist, but as an undergraduate at Worcester Polytechnic Institute, she found herself wanting to know more theory about how things worked. She arrived at Brown in 2006 undecided about a research specialty. One of her first classes was a lab in which students repeated well-known historical physics experiments, and Hanson was assigned one on superconductors that dated back to the 1960s. “It went totally wrong, but it went wrong in the exact same way it went wrong when it was first done, and it was amazing,” Hanson says. Professor Xinsheng Sean Ling started talking about low-temperature physics and said, “By the way, I have an opening in my lab.”
Hanson chose Brown not only for its physics department but also for the “strong presence” of the University’s Sheridan Center for Teaching and Learning. She took on the role of liaison between the physics department and the center, and she also helped to implement an additional training program for Physics teaching assistants.
Hanson also takes her ideas about teaching outside Brown. Last year, through a National Science Foundation fellowship, she teamed up with teachers at nearby Hope High School to develop new ideas for science classes.
“I had always planned to go into industry and work on materials development,” Hanson says. “That’s the reason I became so active in teaching—I figured now’s my chance. But the more I do it, the more it’s feels like a real possibility.”
