Takaaki Kajita
Name in native script: 梶田隆章
active c. 1959, Higashimatsuyama, Saitama, Japan
Japanese physicist who proved neutrinos have mass through atmospheric neutrino oscillations at Super-Kamiokande.
Kajita joined Koshiba's Kamiokande project as a student, using a tank of ultra-pure water and thousands of photomultiplier tubes to count neutrinos. In 1998 he announced that atmospheric muon neutrinos were depleted depending on flight distance — 'smoking gun' evidence of neutrino oscillation. He later directed Tokyo's Institute for Cosmic Ray Research.
Nobel-winning work
Kajita's analysis (Super-Kamiokande, 1998) showed the up/down ratio of muon neutrinos differed exactly as predicted if neutrinos change flavor while crossing the Earth. Oscillation requires nonzero neutrino mass — beyond the original Standard Model — and was the first major evidence of 'new physics' beyond it.
Workplaces: University of Tokyo, Super-Kamiokande Observatory
Japan