Innsbruck Physics Lecture - Tue, 30 Oct. 2018, 17:15 lecture hall A
Francis Halzen – University of Wisconsin
Francis Halzen obtained his PhD in 1969 from the University of Leuven, Belgium and is the Gregory Breit Distinguished Professor & Hilldale Professor at the University of Wisconsin-Madison. He has been a leading scientist in the development of cosmic ray physics and astroparticle physics for several decades. In addition to particles physics research he investigated relations between particle physics and cosmic rays. From early in his career onwards he discussed the possibility of detecting high-energy neutrinos from cosmic sources, such as supernovae and other objects. In the 1990s he initiated the building of a large neutrino detector, AMANDA, in the south polar ice. He next argued vigorously for its successor experiment, the much larger IceCube experiment, which takes data from a 1 km3volume of ice. He again served as a Principal Investigator for this project and succeeded in attracting a number of excellent international collaborators, and also to secure sufficient financing from American and European sources.
The IceCube neutrino observatory is fully operational and its (presently) most important result is the breakthrough discovery of high-energy neutrinos (about 100 times more energetic than the particles accelerated today in the world’s most powerful machine, the LHC at CERN) in 2013, from as yet not firmly identified sources outside the Galaxy.
Francis Halzen is an inspiring example of a scientist who, though coming from a different research discipline, had the foresight to see where the next breakthrough in our understanding on the universe is likely be found, and who has the energy and leadership to realize this vision. He has authored more than 500 publications, served in a great many of committees and review panels, and received numerous awards and international recognitions (among them the Physics World Breakthrough Award 2013and Balzan Prize 2015), but is also well-known for his active engagement in communicating scientific results (Recipient of the Best American Science Writing2000).
IceCube: Opening a New Window on the Universe from the South Pole.
The IceCube project has transformed a cubic kilometer of natural Antarctic ice into a neutrino detector. The instrument detects more than 100,000 neutrinos per year in the GeV to PeV energy range. Among those, we have isolated a flux of high-energy neutrinos of cosmic origin. We will explore the IceCube telescope and the significance of the discovery of cosmic neutrinos. We recently identified their first source: alerted by IceCube on September 22, 2017, several astronomical telescopes pinpointed a flaring galaxy, powered by an active supermassive black hole, as the source of a cosmic neutrino whose energy exceeds 300 TeV. Most importantly, the large cosmic neutrino flux observed implies that the Universe’s energy density in high-energy neutrinos is close to that in gamma rays, suggesting that the sources are connected and that a multitude of astronomical objects await discovery.
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