DeepCore construction begins

A schematic layout of IceCube DeepCore.
A schematic layout of IceCube DeepCore. The upper diagram shows a top view of the string positions in relation to deployed IceCube strings. It includes two additional strings, situated close to the central DeepCore string, that were deployed in the 2010/2011 austral summer. Credit. IceCube Collaboration

The first specialized string for DeepCore—the infill at the center of the IceCube array consisting of eight more densely deployed strings of modules—was successfully deployed in January 2009. DeepCore substantially enhanced the detector’s sensitivity at low energies: The amount of light produced when a neutrino interacts is proportional to the neutrino energy, so spacing the light sensors closer together allows the fainter low-energy events to be seen.

DeepCore started acquiring physics data in April 2010, and in May 2010, it made its first observation. DeepCore is vital for observations of lower-energy neutrinos used to investigate neutrino properties such as oscillations and searches for additional types of neutrinos, among other analyses.

Read more here, here, and here.