Research at the Super-Kamiokande neutrino observatory in Japan ground to a halt last November after a routine cleaning ended in disaster. Workers were refilling the 135-foot-high water tank, which is lined with sensitive light-detecting tubes that pick up flashes triggered by neutrinos. When the tank was 80 percent full, roughly 7,000 of the submerged tubes imploded, leaving the detector crippled.
Officials at Super-K think insufficient padding placed on the bottom of the observatory may be to blame. Workers had to walk across this padding during cleanup and repair. Ironically, those footsteps probably weakened the tubes, leaving them unable to support the weight of the water when Super-K was refilled. The damage to the facility, which four years ago provided the first evidence that neutrinos have mass (see Discover, August 2001), is a major blow to particle physics research. Super-K director Yoji Totsuka says the facility will resume limited experiments by the end of this year, utilizing its remaining 5,000 tubes. But getting back to full strength may take four years and $20 million.
Super - K under construction in 1995.Photograph courtesy of Kamioka Observatory/ICRR/University of Tokyo