Special High Energy Physics Seminar

Note special day and time.

Speaker: Donglian Xu, University of Wisconsin

Title: Exploring the Universe with “Icebound” Neutrinos

Date: Wed, 21 Mar 2018, 11:00 am – 12:00 pm
Type: Seminar
Location: 1400 BPS Bldg.

The IceCube Neutrino Observatory has recently discovered a diffuse extra-terrestrial neutrino flux, marking the dawn of high-energy neutrino astronomy. Among the observed flux, we expect an equal fraction of neutrino flavors at Earth due to averaged neutrino mixing over astronomical distances. Thus, although yet to be observed, a significant amount of tau neutrinos is expected to be present despite of their rare production at the source(s). Furthermore, high-energy (>TeV) tau neutrino production in the Earth's atmosphere is extremely low. Therefore, identification of TeV–PeV tau neutrinos in IceCube will not only provide clean reconfirmation on the astrophysical origin of the observed neutrino signal, but also enable us to test fundamental neutrino properties over extremely long baselines via precise measurement of neutrino flavor ratios — as many new physics models predict it to be significantly deviating from equal fractions.

As the world's largest neutrino detector, IceCube provides rich scientific opportunities, such as the use of atmospheric neutrinos to measure neutrino oscillation parameters precisely, as well as unveiling the century-long puzzle of the origin of cosmic rays. Because neutrinos are neutrally charged and weakly interacting, they can traverse cosmological distances without being absorbed and point back to their source when detected at Earth. This makes neutrinos unique messengers to trace the high-energy Universe. With the extensive multi-messenger program that IceCube has cultivated, the once elusive neutrino sources are within reach.

I will present on the dedicated, ongoing effort to identify astrophysical tau neutrinos, a hunting campaign for neutrino sources and the perspective of next generation detector upgrade, IceCube-Gen2, in both low and high energies.