Search for Tau Neutrinos in IceCube Data

University Of Alabama Tuscaloosa, Tuscaloosa AL

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 provides funding for the University of Alabama (UA) group to search for a particular type ("flavor") of neutrino, the tau neutrino, in the IceCube data. Tau neutrinos have a negligible background from the atmosphere and would be a certain sign of astrophysical origin as well as offering insight into neutrino physics and oscillation in distant sources. The PI will continue and enhance high school outreach by hosting an IceCube Masterclass: a one day event which gives high school students the chance to work with real IceCube data. The PI will develop a new Masterclass activity based on the UA group's tau neutrino research. The PI participates in public outreach activities that highlight IceCube's unique location and science goals. If the astrophysical neutrino flux arises from pion decay as a result of cosmic ray acceleration in shocks, and assuming standard neutrino oscillation parameters, the detected neutrinos at Earth should consist of equal fractions of electron, muon and tau neutrinos. However, tau neutrinos have yet to be unambiguously identified in the astrophysical neutrino flux. The group will build on a proven track record in the tau neutrino channel and extend the search to lower energies and to previously unexplored signatures. With three more years of IceCube data, lower energy thresholds and increased signal sensitivity, tau neutrinos could be detectable by the end of the funding period.