Which experiment announced evidence for neutrino oscillation in 1998 using atmospheric neutrinos?

The Super-Kamiokande experiment announced evidence for neutrino oscillation in 1998 using atmospheric neutrinos.

Super-Kamiokande is a large water Cherenkov detector in the Kamioka mine in Japan. Its enormous tank contains ultrapure water surrounded by thousands of photomultiplier tubes, which detect faint flashes produced when particles pass through the water.

The experiment compared atmospheric muon neutrinos arriving from different directions. Neutrinos traveling through Earth crossed much greater distances than neutrinos produced directly above the detector. Super-Kamiokande found that many expected muon neutrinos were missing, while the pattern depended on travel distance and energy. This supported the idea that neutrinos change flavor as they propagate.

Neutrino oscillation requires neutrinos to have nonzero masses, although the experiment did not by itself determine every neutrino mass. The result helped overturn the older assumption that neutrinos were massless and earned the 2015 Nobel Prize in Physics for Takaaki Kajita and Arthur B. McDonald, whose work included Super-Kamiokande and the Sudbury Neutrino Observatory.