Nuclear mattersPure samples of telltale xenon-133 gas help detectors sniff out nuclear tests
Nuclear explosions produce an excited form of the radioactive gas xenon-133, called xenon-133m, in which the atomic nucleus is boosted to a higher-energy state, but it is not known exactly how sensitive detectors are to this form because there has been no way to make pure samples of xenon-133m with which to test them; until now
Conducting stealth nuclear weapons tests has just become more difficult, as ultra-pure samples of a radioactive gas could soon make it harder for nations to carry out nuclear tests in secret. A global network of monitoring stations constantly samples the air for signs of underground nuclear tests. One thing the stations look for is the radioactive gas xenon-133. Nuclear explosions produce an excited form called xenon-133m, in which the atomic nucleus is boosted to a higher-energy state, but it is not known exactly how sensitive detectors are to this form because there has been no way to make pure samples of xenon-133m with which to test them.
New Scientist reports that now, Kari Peräjärvi of the Radiation and Nuclear Safety Authority in Helsinki, Finland, and colleagues have solved the problem. The team placed a cloud of xenon-133 atoms inside a magnetic trap and then jolted it with oscillating electric and magnetic fields. This pushed out the unexcited form, leaving only the excited form behind. The work could make nuclear monitoring with air samples more reliable.
James Acton of the Carnegie Endowment for International Peace in Washington, D.C. says, however, that the gas may stay trapped below ground if there are no cracks for it to seep through, making on-site visits — not currently required by international law — a better approach.
—Read more in K. Peräjärvi et al., “Ultra-high Resolution Mass Separator — Application to Detection of Nuclear Weapons Tests,” Applied Radiation and Isotopes 68, no. 3 (March 2010): 450-53 (sub. req.)
