Mapping World Nuclear Activity

[rdunk]

It may be getting harder and harder to hide from what the neutrinos can freely tell! This such data may be of benefit to some countries, and may make it difficult for other countries.

Map of the World's Neutrinos Exposes Nuclear Activity Wherever It's Happening

MIT Technology Review
By Faye Flam on September 10, 2015

A seemingly unsubstantial particle called a neutrino is opening a new window on the world.

As far as useful discoveries go, the neutrino didn't look promising. These ghostly particles are produced by the sun, by radioactive elements, and by nuclear reactors, from which they speed outward with zero charge, almost no mass, and a nearly complete indifference to matter.

Last week, scientists released a map showing what the world would look like if we could see all the billions upon billions of neutrinos that emanate from the surface of the planet each second. It turns out that neutrinos' uncontainable nature is potentially bad if you're trying to hide something going on at a nuclear plant, but good if you want to monitor other people's nuclear activities. Dark spots on the map indicate nuclear reactors and parts of the earth's crust rich with radioactive uranium and thorium, which emit neutrinos when they decay.

The technology to pick up the tracks of elusive neutrinos has continued to improve since the first official detection in 1959 at the Savannah River nuclear power plant in Georgia. While most detectors have been built with the goal of studying the nature and behavior of neutrinos, scientists are starting to consider using neutrino detectors to probe the earth's interior and monitor nuclear activities.

The map, published in Nature Scientific Reports, was created using neutrino signals captured in two detectors, one in Italy and one in Japan, says William McDonough, a geophysicist at the University of Maryland and a coauthor on the paper. The rest of the map was constructed using data about the composition and density of the earth's crust and the location of the world's reactors.

Dark patches appear around mountain ranges where there's a lot of naturally occurring radioactive decay, he says. The Himalayas are responsible for a massive dark patch over southern Asia. Some of the dark spots are reactors, especially around France. (Technically, the ones from nuclear power plants are called antineutrinos—the antimatter counterpart to neutrinos—but how the two types of particles differ is still being worked out.)

What renders neutrinos detectable at all is the fact that there are a lot of them. The detectors employ apartment building-sized tanks of mineral oil, through which trillions of neutrinos pass unobstructed each second. But every once in a while, one of them hits the nucleus of a hydrogen atom just so, annihilating a proton and leaving behind other particles—a positron and a neutron—which will register a signal.

Finding clandestine reactors is not as important as monitoring known ones, says physicist Patrick Huber of Virginia Tech. Reactors give off heat that can be detected easily with infrared sensitive satellites. We knew where all the Soviet reactors are, and now we know where they are in Russia and North Korea. What we don't always know is how and when they are being used.

More: http://www.technologyreview.com/news/541146/map-of-the-worlds-neutrinos-exposes-nuclear-activity-wherever-its-happening/?utm_campaign=socialsync&utm_medium=social-post&utm_source=facebook