Category Archives: AAAS Annual Meeting 2011

The atomic detectives


By Margaret Harris in Washington DC

One July day not so long ago, a shipment of scrap metal entered an EU seaport from somewhere outside the EU. No-one who watched the shipment being unloaded saw anything out of the ordinary. But when it went through the port’s radiation detector, alarm bells began to ring – and they rang again the next month with another shipment, and for a third time in October the same year. What was going on?

This is the story of “Find 33,” a case study from the emerging science of nuclear forensics that formed the basis of Klaus Mayer’s talk at an AAAS session on combating nuclear terrorism. Mayer, a scientist at the Institute for Transuranium Elements (ITU) in Karlsruhe, Germany, was called to investigate Find 33 after national authorities had isolated which particular bits of scrap were setting off the detectors.

The initial data were puzzling. The amount of enriched uranium in the four pieces of suspicious scrap ranged from a few percent to over 90% – values that suggested a mixture of commercial-grade and weapons- or research-reactor grade contamination. Could they have a common origin? Or were Mayer and his team dealing with multiple uncontrolled sources of radioactive and nuclear material?

After more detailed tests, a clearer picture began to emerge. A sample from the first piece of scrap – an extremely dirty funnel-shaped object – was found to contain 0.33% uranium by weight, of which the fraction of enriched uranium (U-235, the isotope used in both nuclear weapons and reactor fuel) was 9%. This was unusual: 9% is too high for a commercial reactor, which typically uses fuel that is <5% enriched, but too low for fast-breeder reactors (20%), submarine fuel (20-45%) or weapons (>90%). However, after grinding the sample into powder, Mayer and his team were able to show that it was actually a mixture of 3.6%-enriched and 20%-enriched particles. Radiochemical tests also showed that the uranium in it was old – it hadn’t been chemically purified since 1962.

ITU_Find33pic.jpgA piece of contaminated scrap from Find 33. (Courtesy: VROM-Inspectorate)

The other three scraps were analysed in a similar fashion, turning up a mixture of ages (June 1959, June 1972, October 1983) and enrichment fractions that ranged from a few percent for the second scrap to a sobering 89% for the fourth. This indicated that wherever these scraps had come from, it had to be someplace that had been producing a mixture of light-water reactor fuel, fast-breeder reactor fuel, submarine fuel and material for research reactors or weapons for at least 30 years, between the late 1950s and early 1980s.

And there were only two sites that fit the bill.

Sadly for this story’s narrative arc, Mayer declined to provide any further information on the two candidate facilities, citing an ongoing investigation. One thing, however, is certain: with 207 illicit trafficking incidents recorded in 2010 alone, the atomic detectives are keeping busy.

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Kepler basks in its success

By Michael Banks in Washington, DC

It was all things exoplanets this morning at the 2011 annual meeting of the American Association for the Advancement of Science here in Washington, DC.

It’s quite amazing what NASA’s planet hunter – the Kepler mission – has managed to find. So far, in data released in February, the Kepler probe has discovered 1235 planet candidates. 68 of them are Earth-sized planets with 54 thought to be in the habitable zone of a star – an orbit that is not too close or far away from the star so the conditions are ideal for life.

Maybe one of the most interesting potential planets is “KOI 326.01”. It is actually smaller than Earth and is in the habitable zone of its star. However, like most of the planets Kepler has so far spotted, the planet has yet to be confirmed.

When asked further about the planet, William Borucki, from the NASA Ames Research Centre, who gave an overview of the mission, would not single it out for special attention.

The next speaker in the session was Matthew Holman from the Harvard-Smithsonian Centre for Astrophysics, who told delegates that Kepler has found 45 three-planet systems, eight systems with four planets in them, one with five and one with six planets.

Even though Kepler will be studying exoplanets for another three years, astronomers are also thinking about what comes next.

Sara Seager from MIT is planning to send a host of Cubesats into orbit in the next few years to study exoplanets. These small-sized satellites – each around 20 × 20 × 20 cm – would each study a single star to look for planets orbiting them.

Only a few years ago, exoplanet science was thought of as a “cottage industry” according to Seager. “No-one thought how dominating the field of exoplanet research would now be,”she says. As the planets found by Kepler are confirmed and studied further over the coming years, that dominance is likely to continue.

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Talking particle physics

By Michael Banks in Washington, DC

Today I met up with Harvard University theorist Lisa Randall to speak to her about all things particle physics.

Randall was speaking about the Large Hadron Collider at CERN in a plenary lecture here at the 2011 American Association for the Advancement of Science meeting in Washington, DC. She is definitely a physicist in demand with a crowd of no fewer than 20 people wanting to ask her a question after the talk.


Randall is looking forward to the next few years now that the LHC is finally starting to deliver data but would not single out one particular area of LHC research for special attention. “It’s all exciting,”says Randall.

Randall has been vocal about the decision to close the Tevatron at Fermilab later this year. It was proposed that the accelerator continue for another three years in search for the Higgs boson but it will now close by October 2011 to make way for experiments in neutrino and muon physics. “I was trying to push them to keep it running,” says Randall. “[Researchers at Fermilab] would have something significant to say about the search for the Higgs boson [if it was allowed to continue].”

Will the prospect of no leading high-energy accelerator now hit US particle physics? “Physics is universal so it doesn’t matter where the experiments are performed,”says Randall. “But it does impact on the training of young physicists. It would be nice for Americans to be a part of it more.”

Randall is also busy putting the finishes touches to a new book called Knocking on Heaven’s Door, which is about the LHC and other topics such as dark matter as well as covering the “nature of what science is and what scientific creativity is”. The theorist will publish the book in the autumn and will no doubt be hoping it has a similar success to her 2005 hit book Warped Passages.

Make sure you catch the full interview with Randall on in the coming weeks.

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AAAS by the numbers

By Margaret Harris

As a physicist, I’m a big fan of numbers, so here are a few outstanding ones I collected from today’s sessions at the AAAS meeting:

NASA’s Space Shuttle can carry up to 16,000 tonnes of cargo back to Earth from the International Space Station (ISS). After the shuttle is retired later this year, any cargo that needs to be shipped from the ISS will have to fit inside a Russian Soyuz capsule, which has a cargo capacity of 50 kg. (Source: NASA astronaut Sunita Williams)

Of the estimated 60 million tonnes of krill in the ocean around Antarctica, up to 5 million tonnes can be harvested each year without harming the long-term sustainability of the population. (Source: George Watters, US Antarctic and Marine Living Resources Program)

2.1% of the 2900 employees of NASA’s Goddard Space Flight Center have a disability – one of the highest percentages of any US government employer. (Source: Dan Krieger, program manager, NASA/Goddard)

Once it’s up and running in the early 2020s, the Square Kilometer Array radio telescope will produce 400 terabytes of compressed data every second. Without compression, it is estimated that the amount of data generated by SKA would exceed the current traffic of the entire World Wide Web. (Source: Bernie Fanaroff, project director, SKA South Africa)

And finally…

A 10 stone person would have to expel bodily gases at a rate of 17 million m/s in order to achieve lift-off by farting. (Source: Chris Smith of The Naked Scientists)

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Avoiding nuclear famine

Hotting up: Michael Mills from the National Center for Atmospheric Research in Boulder, Colorado, shows how a nuclear war could affect the ozone

By Michael Banks in Washington, DC

“It’s a real bummer – quite depressing.” That is the summary of the first session I attended at the 2011 American Association for the Advancement of Science (AAAS) conference here in Washington, DC. Well at least according to Alan Robock from Rutgers University in New Jersey.

The session was about nuclear conflict and its effect on the climate, or more specifically what would happen to it if India and Pakistan had a nuclear war. Rather depressing stuff to hear at 8.30 a.m.

Luke Oman from NASA’s Goddard Space Flight Center studied what effects 100 nuclear bombs – each 15 kilotonne of TNT equivalent in explosive force – would have if detonated in the area. The number of bombs represents around 70% of the total number of warheads the two countries have.

Oman says such a concoction of explosions would create around 5 terragrams of black carbon – or soot – in the atmosphere. This would quickly rise towards the troposphere causing it to increase in temperature by around 30 degrees. The result of the soot would also lead to a global surface temperature drop of around 1.25 degrees and a 10% decrease in global precipitation.

All gloomy stuff, but the next speaker had even more bad news. Michael Mills from the National Center for Atmospheric Research in Boulder, Colorado, used similar models and found that around 30% of the ozone layer would be obliterated only two years after the event.

This would have untold consequences on ultraviolet (UV) levels all over the world. Indeed, Mills calculates UV radiation would increase so much so that in London the level would be around 13 (anything above 11 is considered extreme and with the recommendation to stay indoors) while Washington would be around level 16. This, Mills concluded, would all have a major effect on agriculture leading to a “nuclear famine”

A bummer indeed, and Robock summed up the ultimate aim of all this work. “We hope that people in this city will hear [the conclusions of these talks] and rid the world of nuclear weapons for good.”

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Adaptive optics on a human scale

By Margaret Harris in Washington, DC

Greetings from Washington, DC, where the 2011 meeting of the American Association for the Advancement of Science is getting off to a gentle start this afternoon before the firehose of information switches on tomorrow.

Between today and Monday (17–21 February) there will be more scientific symposia, plenary talks, career workshops and poster sessions here in America’s capital city than you can shake a very large stick at. In fact, there’s so much going on that I’m not the only one from attending this year: my colleague Michael Banks is navigating DC’s excellent Metro system as I type this, and between the two of us we’ll try to bring you as much of the conference’s physics news as possible.

One of the themes of this year’s conference is interdisciplinary science, and that was certainly on display at this afternoon’s press briefing on adaptive optics. Regular readers of Physics World will already know that adaptive optics is not just for astronomers anymore – we published a feature by Alan Greenaway on adaptive optics in cell biology just a few months ago, in August 2010 – but it was still surprising to find an astronomer (Norbert Hubin of the European Southern Observatory) sharing the stage with a biophysicist (Eric Betzig of the Howard Hughes Medical Institute) and an opthalmologist (Joseph Carroll, Medical College of Wisconsin).

Hubin, of course, is interested in adaptive optics on a grand scale – tools like laser guide stars, and systems of actuators that can make 100 adjustments to a telescope mirror every milisecond, producing images up to three times sharper than the Hubble Space Telescope despite Earth’s turbulent atmosphere.

Betzig, for his part, uses genetic engineering to label clumps of mouse neurons with a fluorescent marker. Once the mouse matures, these glowing clumps become his “guide star” when he images processes that take place up to 500 microns below the surface of a live mouse’s brain.

And Carroll is using adaptive optics to image the human retina on a cellular level, with the goal of diagnosing diseases like glaucoma and diabetic retinopathy at earlier stages, before they cause irreversible damage. “We hope to be able to tell people 10 years before they would have known otherwise that they have this disease, and then treat them,” he told me.

Both Carroll and Betzig emphasized that their adaptive-optics work is still in its early stages – “We are neophytes compared to astronomers,” Betzig admits – but there’s a clear sense of excitement about where this technology could go in the future, as more and more scientists pick up on these astronomy-inspired “tricks of the light” and adapt them for their own needs.

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