The Next Generation of Neutrino Astronomy
What is IceCube? In short it will be the largest neutrino telescope in the world. Located at the South Pole, this one cubic kilometer detector will allow scientists to see neutrinos at better resolution, improved accuracy and with larger acceptance than ever before. While the first detector built to this scale, the concept of this type of telescope has been implemented before, underwater and underice. IceCube seeks to build on the successes of previous neutrino experiments and give astronomers a chance to discover even more amazing attributes of the universe!
The IceCube collaboration consists of over 20 Universities and instututions spread out over several continents. The group bring expertise and experience from many of the projects similar to IceCube that have come before. Previous generation experiments such as Super-Kamiokande and MACRO have proved the dimensions of experiments needed for discovery should have been orders of magnitude larger. AMANDA and Lake Baikal are proving that dimensions on the order of 10000 m2 can be obtained using natural deep media such as polar ice or the depth of a Siberian Lake. Antares, a project in the Mediterranean Sea will prove the feasibility of a larger underwater detector that will complement IceCube.
Icecube itself is a one kilometer cubed array of optical modules designed to detect Cherenkov light emitted by high energy muons, which are the byproduct of neutrino interactions in the water or ice. When completed, IceCube will have 80 strings buried in the ice. Each of these 2.5 kilometer strings will have 60 optical modules spaced about 17 meters apart located on the bottom kilometer of the string. With a total of 4800 OMs, this gives IceCube a total instrumented volume of 1 kilometer cubed.
When the OMs detect light from one of these particles they amplify it, time stamp it, digitize it and send it to the surface. When a number of OMs detect the same event, it is possible to reconstruct a track, or the path of the incoming muon. When we know the path of the muon, we also know the path of the neutrino that produced it. We can then project that path 'backwards' to see what point source created the neutrino in the first place.
Another part of of the project that is shown in the first image is called IceTop. Ice top is a one kilometer square extensive air shower array lying directly above IceCube with the same hexagonal layout. Using 160 surface Cherenkov detectors (presumably two per string) this array can be used for several purposes. As it relates directly to IceCube, this will help in background rejection. As a matter of fact IceTop will have some veto power over IceCube to help discriminate actual signals as opposed to atmospheric muon background. This will also have the additional capability to be used as a separate tool to study the same type of phenomena for air-shower physics (for instance the composition of cosmic rays). The effective energy range for IceTop will be 1015 eV to 1018 eV, providing a broad range of energies extending to the beginning of extra-galactic sources.
But how do the strings get underice? How does a muon emit light? What is AMANDA? In this web site, you will have a chance to explore some of the ideas beind this experiment, as well as learn about the technical aspects of the project and the physics that underlies the whole thing. Finally, you will be able to see in depth one small part of the program that deals with the accuracy of the telescope. This is the project that I am working on as a undergraduate research assistant.
Follow the links below to explore the site!