WATCHMAN Cutaway (IMAGE) Penn State Caption Shown is a cutaway view of the WATCHMAN antineutrino detector, which would be a key part of the Advanced Instrumentation Testbed, a new international multi-laboratory and university collaboration for nonproliferation research. The facility's outer stainless steel tank is approximately 16 meters tall and 16 meters in diameter. It contains some 3,500 metric tons of water. An inner structure of trusses and cables supports about 3,000 photomultiplier tubes, powerful light sensing devices that convert Cherenkov light arising from the antineutrino interactions in the water into a succession of electrical pulses that are readily processed by downstream electronics to extract the antineutrino signature. The support structure conceptual design and these drawings were created by Jim Brennan of Sandia National Laboratories, California branch. Credit Jim Brennan, Sandia National Laboratories, California branch Usage Restrictions Image credit must be published alongside the image. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.