Takaaki Kajita (梶田 隆章 Kajita Takaaki?, born 9 March 1959) is a Japanese physicist, known for neutrino experiments at the Kamiokande and its successor, Super-Kamiokande. In 2015, he was awarded the Nobel Prize in Physics jointly with Canadian physicist Arthur B. McDonald.
Kajita studied at the Saitama University and graduated in 1981. He received his doctorate in 1986 at the University of Tokyo. Since 1988 he has been at the Institute for Cosmic Radiation Research, University of Tokyo, where he became an assistant professor in 1992 and professor in 1999.
He became director of the Center for Cosmic Neutrinos at the Institute for Cosmic Ray Research (ICRR) in 1999. As of 2015, he is at the Institute for the Physics and Mathematics of the Universe in Tokyo and Director of ICRR.
In 1998, Kajita’s team at the Super-Kamiokande found that when cosmic rays hit the Earth’s atmosphere, the resulting neutrinos switched between two flavours before they reached the detector under Mt. Kamioka.This discovery helped prove the existence of neutrino oscillation and that neutrinos have mass. In 2015, Kajita’s shared the Nobel Prize in Physics along with Canadian physicist Arthur McDonald, whose Sudbury Neutrino Observatory discovered similar results. Kajita and McDonald’s work solved the longstanding Solar neutrino problem, which was a major discrepancy between the predicted and measured Solar neutrino fluxes, and indicated that the Standard Model, which required neutrinos to be massless, had weaknesses. In a news conference at the University of Tokyo, shortly after the Nobel announcement, Kajita said, “I want to thank the neutrinos, of course. And since neutrinos are created by cosmic rays, I want to thank them, too.”
One of the first people Kajita called after receiving the Nobel Prize was 2002 Nobel physics winner Masatoshi Koshiba, his former mentor and a fellow neutrino researcher.
Pablo Dorador Ontiveros
Jesús Sánchez García
Dulce Sáez Martínez