Astrophysics and Neutrino Physics With IceCube

University Of California-Berkeley, Berkeley CA

Investigators

Abstract

Embedded deep in the ice cap at the South Pole, the IceCube Neutrino Observatory (ICNO) is the world's largest and most sensitive high energy neutrino telescope. It is a 1 billion-ton detector using the Antarctic ice as a detection medium for high energy atmospheric and astrophysical neutrinos. Most of the neutrinos observed by IceCube exhibit energies in the range expected for atmospheric neutrinos originating from decays of particles produced in extensive air showers by cosmic rays coming from nearby sectors of the Milky Way Galaxy. These may be used to measure the fundamental properties of neutrinos. At higher energies, astrophysical neutrinos are key probes of the high-energy universe. Because of their unique properties, neutrinos escape even dense regions, are not deflected by galactic or extra-galactic magnetic fields and traverse the photon-filled universe unhindered. Thus, neutrinos provide direct information about the dynamics and interiors of the powerful cosmic objects that may be the origins of high energy cosmic rays: supernovae, black holes, pulsars, active galactic nuclei and other extreme extragalactic phenomena. This award will fund this UCB group to use IceCube data to better characterize this astrophysical neutrino flux. They will measure the flux at higher energies than has currently been done, testing for the presence of a high energy cutoff. IceCube's discovery of an astrophysical neutrino flux has attracted great attention from students at all levels and from the general public and garnered much media attention. This group will educate undergraduate and graduate students and postdocs who are attracted to this important question. The award will fund a broad spectrum of outreach activities targeted at the general public and younger students, through classroom and public presentations and popular writing. This group's study will extend IceCube measurements of the energy spectrum both upward and downward in energy, through two searches. The first will use the data for a more accurate measurement of the neutrino flavor ratio: the relative proportion of electron, muon and tau neutrinos in the astrophysical flux. The second study will employ a fit to the energy and zenith angle distributions to separate conventional and prompt atmospheric neutrinos and astrophysical neutrinos. This fit should allow a sufficiently accurate measurement of the atmospheric pion:kaon ratio to constrain air shower models. It will also detect, for the first time, diffractive neutrino interactions, and will also provide constraints on parton distribution functions and nuclear shadowing at high energies.