Just over a year ago, an accident at the Superkamiokande detector in Japan brought neutrino experiments there to a temporary conclusion. Some 60% of the detector’s 11,200 photomultipliers were destroyed. However, the installation of 5200 new photomultipliers is now complete, and data-taking resumed on 8 October 2002.
The instalment of photomultipliers was complete by the end of September, allowing the detector to be refilled with water starting on 3 October. Data-taking resumed as soon as the first row of photomultipliers was immersed, and the refill was complete by mid-December.
To prevent a similar accident from happening again, the new photomultipliers have been encased in rigid bubbles. Their faces are covered with transparent acrylic, while the rest is made of fibre-reinforced plastic.
