This morning, Jim Madsen, physics professor and IceCube researcher from the University of Wisconsin-River Falls, arrived to the PolarTREC training. I and the other KSTF Fellows spoke with Jim at length about the project, including expectations and our roles as PolarTREC teachers. Jim enlightened us about the nature of neutrinos and how the IceCube detector works to detect them. We had a lot of questions for Jim about neutrinos and how we can study them!

What is a neutrino?

* neutrinos are subatomic particles, related to electrons but with no electric charge. They pass through regular matter unchanged (except in rare cases). If it doesn't interact, there is no way to detect it, making it effectively invisible (consider: for our eyes to detect light, the light must interact with molecules in our eye - if it didn't interact, we couldn't see it!)



Where do these neutrinos come from?

* Neutrinos can be created due to radioactive decay of elements like potassium. Nuclear reactors and bombs can create neutrinos; the sun and other stars create neutrinos. But these are "low" energy neutrinos, not what IceCube is trying to detect. IceCube is looking for high energy neutrinos created in "cataclysmic" galactic events, such as collisions of black holes and perhaps mysterious events called gamma-ray bursts.

How can we detect an "invisible" particle?

* On the extremely rare instance when a neutrino hits the nucleus of an atom, it ends up creating a new charged particle which flies through the ice at very high speeds. As this new particle moves though the ice, it causes a dim trail of light called "Cherenkov radiation."