Super-K

Super-Kamiokande neutrino observatory under Mount Kamioka in Japan.

"The observatory was designed to search for proton decay, study solar and atmospheric neutrinos, and keep watch for supernovas in the Milky Way Galaxy.
A neutrino interaction with the electrons or nuclei of water can produce a charged particle that moves faster than the speed of light in water. This creates a cone of light known as Cherenkov radiation, which is the optical equivalent to a sonic boom. The Cherenkov light is projected as a ring on the wall of the detector and recorded by the PMTs. Using the timing and charge information recorded by each PMT (photomultiplier tube), the interaction vertex, ring direction and flavor of the incoming neutrino is determined.
The ability of the Kamiokande experiment to observe the direction of electrons produced in solar neutrino interactions allowed experimenters to directly demonstrate for the first time that the sun was a source of neutrinos."

More information here and here.

Images courtesy of Kamioka Observatory, ICRR (Institute for Cosmic Ray Research), The University of Tokyo.

Note: Thanks to Katy for showing me these super cool brain nuggets.