IceCube Neutrino Observatory

IceCube is located near the Amundsen–Scott South Pole Station. Its in-ice detector instruments roughly one cubic kilometre of ice, with 5,160 digital optical modules attached to 86 vertical strings deployed in deep boreholes. When a neutrino interacts with an atom in the ice, charged secondary particles can emit Cherenkov light. The optical modules detect and timestamp this light; researchers use its pattern to infer properties such as the direction and energy of the event. Since neutrinos interact only rarely and carry no electric charge, they can travel across cosmic distances with little deflection by magnetic fields, offering information about environments that accelerate particles.

Construction took place over seven Antarctic summer seasons, and the detector was completed in December 2010. IceCube was designed to measure high-energy neutrinos and, where possible, identify their sources. Its surface array, IceTop, helps study cosmic-ray air showers, while the denser DeepCore subdetector improves sensitivity to lower-energy neutrinos and supports studies of neutrino oscillations. The observatory is operated by an international collaboration led by the University of Wisconsin–Madison, with support from the U.S. National Science Foundation and partner agencies.

In 2013, IceCube researchers reported the first solid evidence for a high-energy astrophysical neutrino flux, based on events recorded from May 2010 to May 2012. A later milestone involved the high-energy event IceCube-170922A, detected in September 2017. An alert enabled follow-up observations across the electromagnetic spectrum; telescopes observed gamma-ray activity from the blazar TXS 0506+056 in the same region of the sky. Analysis of earlier IceCube data also found an excess of neutrinos from the blazar's direction in 2014–2015. These results provided strong evidence linking the blazar to high-energy neutrinos, while illustrating the value of combining neutrino observations with other kinds of astronomical data.