I arrived at McMurdo Station, Antarctica on Saturday. I'm thrilled to be here. Most people are, even if they've been here for dozens of seasons. But before I tell you how I got here, about the terrain, or about the local economics, I want to answer a common question. Why do you have to go to Antarctica?
My colleagues and I want to solve a puzzle that has left physicists scratching their heads for decades, some would argue a century. We want to know where cosmic rays come from.
We already know where most cosmic rays come from--the sun. Outside of the solar system, the magnetized shock waves left over from a supernova explosion sweep up all of the particles created in that explosion and accelerate them.
The crazy thing is that those supernova remnants aren't energetic enough to account for all of the cosmic rays. We've detected cosmic rays with energies equivalent to a baseball traveling at 90 mph, and they're much lighter! That's a lot of energy! The most energetic cosmic ray carries more kinetic energy than any particle accelerated here on Earth with our most powerful accelerators. And we don't know what produces them or how they do it.
Our best guesses include active galactic nuclei and gamma ray bursts. Active galaxies host supermassive black holes, a spinning disk that accretes matter into the black hole, and a two high power jets that pump up a particle's energy. Gamma ray bursts are the most energetic events in the universe, and with such an explosion, how could one not accelerate particles there?
Neutrinos are the lightest fundamental particle that has mass. They're the electron's tiny, uncharged cousin. At high energies, they travel further than any other type of radiation, such as light or cosmic rays. They're also produced by cosmic rays as they interact with the light leftover from the Big Bang close to their production site. Since the neutrinos don't interact or get absorbed in their journey towards Earth, detecting them would tell us about where cosmic rays are getting accelerated. Not only that, but since neutrinos travel further than light, we can see how the high-energy end of the universe has evolved over time by looking deeper into the universe.
We're hoping to detect a few hundred cosmic rays and a few neutrinos. Neutrinos are notoriously difficult to detect for the same reason they traverse such enormous, cosmological distances--they are very unlikely to interact with anything. Sometimes they do though, so you want a really large detector to be able to see any of them at all. We're simply using the entire continent of Antarctica as our detector. The neutrinos interact with the ice, produce a shower of new particles, which all work together to produce a short blip in radio waves. Similarly, cosmic rays interact the with the atmosphere to produce the shower of particles and a radio blip.
Our experiment, ANITA (or CLETE as my Dad would say), consists of 49 antennas arranged in a cylinder. They're pointed down at the ice to look for those little blips from neutrinos or cosmic rays. The telescope will fly on a balloon at 90,000 ft, and thanks to the circumpolar winds in Antarctica, flies in a circle around the continent. We hope to fly for a month, but dream of beating the record of 54 days.
So that's what we're trying to do here in Antarctica in a nutshell. For another take on this, check out Katie's blog, Neutrinos on Ice.
By the way, if you want to see more pictures, just click on one of the photos in these posts to check out my Flickr stream.