Subatomic Science at the South Pole
Dr. Karen Andeen’s quest to understand elusive neutrinos takes her deep into the polar ice.
At the South Pole, with temperatures hovering near minus 100 degrees Fahrenheit in the winter months, the sun rises and sets just once a year. At an altitude of 10,000 feet, the 100 scientists and support staff working there can experience altitude sickness and trouble breathing. Twenty pounds of clothing and gear weigh down those who venture outside.
Despite these harsh conditions, working at the IceCube Neutrino Observatory is seen as a golden opportunity. Scientists are considered lucky to go once; Dr. Karen Andeen has been twice.
An assistant professor of physics now in her third year at Marquette, Andeen has been involved with IceCube since her days as a graduate student at the University of Wisconsin–Madison. There, she helped build some of the observatory’s 5,160 digital optical modules, which she later tested and deployed into polar ice. Together the modules form the world’s largest neutrino detector, stretching 2.5 kilometers below the South Pole’s surface.
A collaboration involving 300 scientists in 12 different countries, the project is designed to observe particles called neutrinos, a nearly massless, subatomic particle thought to be produced by powerful cosmic events like a black hole or an exploding star. No one has been able to observe high-energy astrophysical neutrinos before; they hardly ever interact with anything and have no electric charge.
When they do interact, they create a cone of blue glowing light, called the Cherenkov effect. In the ice, the index of refraction is higher than in the air, making ice-based experiments more likely to detect this light. “With the clearest ice in the world, the South Pole is the ideal location for the detector,” explains Andeen.
Operating in its completed configuration since 2011, IceCube is now in a data-collecting phase. Andeen and her students help analyze some of the 100 gigabytes of data transmitted via satellite every day from IceCube (with vastly more carried out by hand at the end of the season). In Marquette’s Wehr Physics Building, she is also building and testing prototype detector panels for future deployment. With no graduate students in the department, undergraduate students are heavily involved in testing and analyzing data from the prototypes.
Being able to focus on teaching is one of the reasons Andeen and her husband Dr. Tim Tharp, also an assistant professor of physics, chose to settle at Marquette. “We wanted to be able to research but also be able to focus on teaching undergrads, so Marquette is a really perfect fit,” she says. After meeting at UW–Madison, the couple spent a few years in Geneva, Switzerland, where both worked on separate projects at the CERN particle physics laboratory. Now back in their native Midwest, the couple can be close to family while remaining connected to their scientific passions — Tharp’s continued antimatter research in Geneva and Andeen’s research a hemisphere away at the South Pole.
