In a major setback for neutrino observations, the Super-Kamiokande neutrino detector in central Japan has been knocked out of commission during repairs to the $100 million facility.
Buried a kilometer underground in a mine, Super-Kamiokande is a 39-meter-by-41-meter tank of water lined with 11,146 photomultiplier tubes that watch for a characteristic glow, known as Cerenkov radiation, from the statistically rare interaction of ephemeral neutrinos and atomic particles in the water. In 1998, it provided researchers with the first convincing evidence that neutrinos have mass.
CREDIT: ICRR/UNIVERSITY OF TOKYO
The tank was emptied in August to replace 100 burned-out tubes and was being refilled on Monday when more than half of the tubes suddenly shattered in an apparent chain reaction. Yoji Totsuka, director of the University of Tokyo's Institute for Cosmic Ray Research, which heads an international collaboration operating Super-Kamiokande, says he has no idea what caused the accident or how soon the facility can be put back online. One scientist estimated that it could cost $10 million just to replace the tubes.
