Neutrino Astrophysics with IceCube
With the discovery of the neutrino 50 years ago the idea emerged to build a detector large enough to study neutrinos from astrophysical sources. High energy neutrinos as cosmic messengers from the Universe represent a new tool that will address some of the most exciting questions in extreme astrophysics, cosmic ray physics and particle physics.
The IceCube detector, currently under construction at the South Pole, is a large-scale detector to identify the sources of the highest energy neutrinos. When completed in 2011, IceCube will occupy a cubic kilometer of deep Antarctic ice, from a depth of 1450 to 2450 meters. It will provide a new window to the Universe to answer questions about phenomena as diverse as supernovae, dark matter, Gamma Ray Bursts, and active galaxies. It will also produce new and exciting challenges -- the history of astronomy shows that forays into new wavelength regions have invariably resulted in the discovery of new phenomena.
Neutrinos are notoriously hard to detect and large detector volumes are necessary to see a sufficient number during the lifetime of the detector. Nearly 5000 optical modules with photomultiplier tubes in the deep ice will comprise the finished Observatory. These light detectors register the Cherenkov light produced by neutrino-induced muons going through the detector volume. The potential signal of astrophysical neutrinos is hidden in a large background produced by muons from cosmic ray interactions in the atmosphere. In IceCube, the Earth is used as a filter to search for upward going neutrino events.
IceCube continuously scans the skies for supernova explosions in our galaxy and, possibly, for the birth of the supermassive black holes that power quasars. As the strings of the IceCube detector come online, data becomes available for analysis almost immediately. At the beginning of 2008, 2400 in-ice optical modules were already deployed.
UW-Madison is the lead institution for the IceCube project funded by the Division of Physics and the Office of Polar Programs of the National Science Foundation. IceCube is a collaboration that, by 2008, includes over 30 institutions from the United States and around the world. IceCube graduate students contribute to the design, construction and calibration of the hardware and software of IceCube, often traveling to the Amundsen-Scott South Pole Station to assist with deployment and maintenance. In Madison, aside from a strong involvement in all the science aspects of the experiment, from point-source studies and Gamma-Ray bursts, to diffuse fluxes of neutrinos and supernova collapses, and astrophysical source modeling, we lead the data acquisition efforts and contribute to the preparation of all the tools for data analysis such as reconstruction of particle tracks and simulation. Along with faculty at UW-Madison, graduate students are also doing R&D for enhancements to IceCube, taking advantage of the long and successful history of an experiment at the South Pole. This includes the possibility of detecting the highest energy neutrinos by radio techniques.
The neutrino astronomy group can offer graduate students hardware as well as data analysis experience. Also a theory effort with a long history in neutrino astronomy supports the experiment.