Koshiba wins Nobel Prize

Physicist to share top honor with two Americans

STOCKHOLM — Masatoshi Koshiba, professor emeritus at the University of Tokyo, and two American researchers won the Nobel Prize in physics on Tuesday for “pioneering contributions to astrophysics,” including the detection of cosmic neutrinos and cosmic X-ray sources.

Koshiba, 76, and Raymond Davis, Jr., 87, of the University of Pennsylvania, will share half the prize, worth 10 million kronor ($1 million), for their research into cosmic neutrinos.

Riccardo Giacconi, 71, of the Associated Universities Inc. in Washington, D.C., will get the other half for his construction of instruments needed to investigate cosmic X-ray radiation, which is absorbed in the Earth’s atmosphere.

“I can only say I am happy,” Koshiba told reporters in Tokyo Tuesday evening.

Koshiba is the 11th Japanese to win the Nobel Prize, and the third Japanese laureate in as many years. Last year, Ryoji Noyori, a Nagoya University professor, won the chemistry award, after Hideki Shirakawa, professor emeritus at Tsukuba University, won it in 2000.

Koshiba was awarded the prize for his pioneering work in the detection of neutrinos, elementary particles that come from outer space.

He is the founder of the Kamiokande and Super Kamiokande neutrino-detecting observatories, located 1,000 meters underground at a mine site in Gifu Prefecture.

In 1998, the Super Kamiokande became the world’s first observatory to confirm that neutrinos have mass.