Within hours of North Korea’s fourth nuclear test on 6 January, data pouring from seismic monitoring stations had shown that the explosion was almost certainly not a hydrogen bomb — contrary to claims made by the totalitarian, isolated state. Scientists are now relying on luck — and prevailing winds — to find out more about the design of North Korea’s device.
They hope that radioactive gases leaking from the underground explosion will be picked up by a global network of monitoring stations managed by the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), based in Vienna.
By comparing the ratios of various isotopes of xenon, an unreactive gas that can permeate the rock that sealed the blast, researchers might be able to determine whether the bomb was made from uranium or plutonium, and whether it was a conventional fission device, or a smaller, more-efficient "boosted" fission bomb.
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