Watchman

A test bed that’s designed to help the effort to find hidden nuclear reactors could also help reveal the hidden workings of exploding stars.
Watchman is designed to lead to bigger instruments that could detect reactors thousands of miles away. The plan calls for it to be built in a mine on the coast of England. The mine is about 15 miles from a pair of nuclear reactors. They produce huge numbers of particles called antineutrinos. These particles zip through solid matter as easily as they zip through space.
Watchman will consist of a large tank of water mixed with a special element. The tank will be lined with light detectors. Rare interactions between antineutrinos and atoms in the tank will produce double flashes of light.
But some of those flashes may be triggered by sources other than the reactors. Some types of exploding stars, for example, also produce antineutrinos.
When a heavy star reaches the end of its life, its core collapses and its outer layers blast into space as a supern