The IceCube neutrino observatory is a 1 gigaton Cherenkov detector using Antarctic ice as a detection medium for high energy atmospheric and astrophysical neutrinos. The experiment is located at the South Pole, right in the middle of the map above. (Just for fun, this map shows the winds -- it is pretty tough down for the IceCube collaborators that go down there!) The official webpage for IceCube is here, and includes the latest weekly report from the pole!
Proposed as a telescope for neutrino astronomy, deployment of IceCube optical modules into the ice began in 2005. The last of the 5160 digital optical modules (DOMs) which make up the 86-string IceCube detector, were deployed in late 2010. The above event display is of a neutrino event that occurred in the ice, sending a muon upward through the detector. IceCube is now running in this configuration and has discovered exciting astrophysical neutrino events.
We joined IceCube because the detector can also be used for particle physics studies that are well-aligned with out interests. Our first analysis, performed jointly with the University of Wisconsin IceCube Collaborators, was a sterile neutrino search. The signature of a sterile neutrino in IceCube is a resonant depletion of up-going muon neutrinos in the TeV energy range, caused by matter effects as the neutrino propagates through the Earth. The resonance will occur at a specific energy and zenith angle which depends on the oscillation parameters. You can learn all about this in Ben Jones' thesis here. The result has been submitted to PRL and is available here from arXiv.
The plots above show the final result. Here is the abstract from the PRL: "The IceCube neutrino telescope at the South Pole has measured the atmospheric muon neutrino spectrum as a function of zenith angle and energy in the approximate 320 GeV to 20 TeV range, to search for the oscillation signatures of light sterile neutrinos. No evidence for anomalous νμ or ̅νμ disappearance is observed in either of two independently developed analyses, each using one year of atmospheric neutrino data. New exclusion limits are placed on the parameter space of the 3+1 model, in which muon antineutrinos would experience a strong MSW-resonant oscillation. The exclusion limits extend to sin22θ24≤ 0.02 at Δm2 ≈ 0.3 eV2 at the 99% confidence level. The allowed region from global analysis of appearance experiments, including LSND and MiniBooNE, is excluded at approximately the 99% confidence level for the global best fit value of |Ue4|2."
This analysis employs a very useful piece of code called NuSQUIDS, written by Carlos Arguelles, that allows the calculation of the resonance as the neutrinos pass through the earth. The more general version of the code, SQUIDS, is described here.
We are now embarking on expanding the sterile analysis to include 5 years of data. We are also searching for signals of Lorentz violation and neutrino decay in the IceCube data.
This page was updated May 2016