IoP Colloquium: Francis Halzen (U. of Wisconin-Madison)
IceCube: Building a New Window on the Universe from Antarctica
Francis Halzen is one of the most important astroparticle physicists worldwide. He led the construction and operation of the IceCube neutrino telescope at the South Pole, that allowed the discovery of cosmic high-energy neutrinos. He has won prestigious international prizes like the Balzan prize, and the European Physical Society Prize. Last but not least, he is an outstanding speaker, so we encourage all physicists and astronomers to join us this Thursday!
ABSTRACT: Weakly-interacting neutrinos are ideal astronomical messengers because they travel through space without deflection by magnetic fields and, essentially, without absorption. But this weak interaction also makes them notoriously difficult to detect, with observation of neutrino sources beyond the sun requiring kilometer-scale detectors. IceCube has discovered a flux of cosmic neutrinos in the energy range from 10 to 10,000 TeV. These are predominantly extragalactic in origin with an energy density that is like the one of high-energy photons detected by astronomical telescopes. Neutrinos are therefore ubiquitous in the nonthermal universe suggesting a more significant role of protons (nuclei) relative to electrons than foreseen. Anticipating an essential role for neutrino astronomy, IceCube is planning a significant upgrade of the present instrument as well as a next-generation detector. Similar detectors are under construction in the Mediterranean Sea and Lake Baikal.