Listening IN on Plutonium

Two years later, federal officials and scientists say the research focuses on better detection of four basic, but inconspicuous, signatures that covert nuclear facilities and materials can emit: distinctive chemicals, sounds, electromagnetic waves and isotopes, or forms of the same element that have different numbers of neutrons, a subatomic building block.

The Iranian crisis could pose a big test of how far that technology has come.

Federal researchers are creating new classes of such remote-controlled aircraft, pushing the art of miniaturisation in what are known as microflyers. Discussion focused on whether such devices could carry minuscule sensors to sniff out atomic activity. That effort is embryonic, experts say. The government8217;s research centres more immediately on developing larger but still stealthy sensors that can detect such key atomic ingredients as uranium hexafluoride gas, which is fed into centrifuges as part of the enrichment process.

One way to track the gas is to detect atmospheric rises in radioactivity as well as the uranium 235 isotope, which is unique to enrichment. Experts say research on that is under way at the Oak Ridge National Laboratory as well as the Los Alamos and Livermore weapons labs. Steve Wampler, a Livermore spokesman, said the laboratory could say nothing 8216;8216;beyond that the work is an important element for proliferation detection8217;8217;.

Another goal, officials say, is to develop remote means of tracking plumes from clandestine sites that leak the chemical byproducts of uranium hexafluoride, revealing the presence of the toxic gas. 8216;8216;That8217;s the smoking gun,8217;8217; a nuclear expert said. Sidney Drell, a Stanford University physicist, lauded the overall effort. 8216;8216;It8217;s important to get, as early as possible, reliable evidence on what may be clandestine facilities,8217;8217; he said.

Tehran8217;s acts have given sudden prominence not only to research meant to improve atomic espionage but, in less classified forms, to aid the nuclear inspectors of the IAEA. Even the less secret versions of such tech can be quite exotic, including sensors that track ghostly particles known as antineutrinos8212;a kind of antimatter.

In the mid-1990s, the IAEA conducted studies to investigate the monitoring of air, water and land for clues. A 1999 agency report found that uranium releases might be detected at distances of up to 64 km, but cautioned that, over wide areas, pinpointing the source would be difficult.

A recommendation of the 2004 meeting was that the US build a secret centre where scientists could practice monitoring the kind of first-generation centrifuges sold by Dr A Q Khan of Pakistan. 8216;8216;The notion of a test bed was really pushed,8217;8217; a participant recalled, using the phrase to describe a centrifuge facility where researchers could conduct surveillance experiments.

Several intelligence experts said they believed Iran was well aware of the range of remote sensors trained on its corners, even if it did not know their specific technical capabilities, and was probably engaged in devising countermeasures. It is a kind of technological intelligence race.

Robert Joseph, US under secretary of state for arms control and international security, called the research vital. 8216;8216;There is an urgency and imperative to invest in the technology to determine which approaches are best. Some will work. Some will not,8217;8217; he said, adding, 8216;8216;But it is the geopolitics that makes this urgent.8217;8217;

New York Times