From Reuters: <http://www.reuters.com/news_article.jhtml?type=sciencenews&StoryID=368141#>
Researchers Probe Accident at Japan Neutrino Lab Last Updated: November 13, 2001 06:54 AM ET TOKYO (Reuters) - Researchers on Tuesday were probing an accident at a key Japanese physics laboratory near Tokyo that could prove a costly setback into global research on neutrinos, ghostly particles that constantly bombard the earth. The accident at the ground-breaking Super-Kamiokande laboratory, a huge underground chamber built more than half a mile down a zinc mine, has rendered it unusable for an undetermined period of time and may have caused some $16.61 million worth of damage, an official at the Education, Science and Technology ministry said. "This is a terrible thing for science," the official said of the accident on Monday morning, in which thousands of light sensors were damaged. "There is only one other facility like this in the world, so this is likely to slow research into neutrinos altogether." The Super-Kamiokande facility has been acclaimed by scientists throughout the world for its 1998 discovery that neutrinos possess mass, a significant find in the world of particle physics. Neutrinos, electrically neutral sub-atomic particles, come into being when cosmic rays hit the earth's upper atmosphere, sending cascades of the elusive motes zipping ghost-like through the entire planet without interacting with matter. At stake in the study of neutrinos is the structure of matter itself, as well as puzzles that have haunted scientists for decades, including whether the universe has sufficient mass to stop expanding and come crashing in on itself. The centerpiece of the Super-Kamiokande facility is a neutrino-detection apparatus that relies on some 11,242 tubes called photomultipliers, or sensors that detect light of certain wavelengths, lining a tank of 50,000 tons of purified water. The tank is about 128 feet in diameter and nearly 45 yards, or 135 feet, long. At the time of the accident, the laboratory had just replaced about 100 failed sensors, which requires draining the tank, Japanese media said. It was when technicians began refilling the tank to continue experiments that the accident took place. Researchers in the control room next to the apparatus felt the floor tremble and heard explosions from the next room, Kyodo news agency said. As a result of the accident, the Education ministry official said, more than half the sensors appear to have been damaged. "It's very hard to estimate the cost or how long it will take before we can use the facility again," he added. "All the damaged sensors will have to be remade and replaced. It could well cost around two billion yen." He said that while investigations into the accident had just begun, it did not initially appear to be due to operator error. "However, when all is said and done, some sort of error in judgement could well be behind this," he added. "It will take quite some time to determine the cause." � Copyright Reuters 2001.
