Colloquium: Prof. F. Halzen
University of Wisconsin - Madison
Abstract : The kilometer-scale neutrino detector IceCube is a discovery instrument covering astrophysics, particle physics and cosmology. Examples of its multidisciplinary mission include the search for the particle nature of dark matter and for additional small dimensions of space. In the end, its conceptual design is very much anchored to the observational fact that Nature accelerates electrons and protons to energies in excess of one hundred and one hundred million Terraelectronvolts, respectively. The cosmic ray connection sets the scale of cosmic neutrino telescopes. The problem in the last five decades has been to develop a robust and affordable technology to build the kilometer-scale neutrino detectors required to do the science. The IceCube detector that transforms ultra-clear deep Antarctic ice into a Cherenkov detector of muons and particle showers initiated by neutrinos of all three flavors, has met this challenge. The instrument collects over 100 atmospheric neutrinos per day, some with energies exceeding by more than 2 orders of magnitude those produced at accelerators. Like atmospheric muons, they provide a calibration beam for the detector that reveals an instrument with superior sensitivity compared to expectations. Its very first scientific results already hint at some exciting science prospects.