Pop goes the neutrino: Acoustic detection of astrophysical neutrinos

Justin Vandenbroucke
UC Berkeley


Interest has grown recently in experimental searches for neutrinos of astrophysical origin, in particular the ~1018 eV neutrinos generated by interactions of the highest energy cosmic rays with the cosmic microwave background. Detecting ~100 of these neutrinos in order to build sky maps and energy spectra would contribute significantly to resolving the mystery of the highest energy cosmic rays and would test fundamental particle physics at ~100 TeV center of mass energy. However, new techniques are necessary to achieve the desired effective volume of ~100 km3. In dense media such as ice, water, and salt, neutrino-induced particle showers heat the medium locally causing it to expand and emit a shock wave that is detectable as acoustic radiation in the 10-60 kHz band. South Pole ice in particular is predicted to have low acoustic attenuation and background noise, making the method significantly more sensitive than the optical Cherenkov technique above 1018 eV. The South Pole Acoustic Test Setup was installed in three IceCube holes in 2007 to measure the properties necessary to determine the feasibility of acoustic neutrino detection at South Pole.