With the week interrupted by both the Fourth of July and a heat wave it seems a good time to serve up a few light snacks rather than a full-blown posting. So here are a few stories in the news recently – none have received a lot of attention yet; we’ll have to see what happens.
New neutron detector might be on its way
Sandia National Laboratories recently announced that its scientists have developed a fundamentally new type of neutron detector – using materials known as metal-organic frameworks and a technique called spectral shape discrimination (SSD) to differentiate between neutrons and gamma rays. Neutrons, of course, are given off by nuclear weapons and neutron detection is (dare I say) critical to efforts to identify nuclear weapons that are being smuggled in preparation for an attack.
Current technology relies heavily on a form of helium with 2 protons and a single neutron, called helium-3. Due to a global shortage of He-3 there is now a fairly long waiting period for new neutron detectors – and this shortage has also hit some forms of physics pretty hard as well. A new type of neutron detector that can cut our reliance on He-3 should be welcomed by both counter-terrorism folks and physicists alike. And in the “but wait – there’s more” category, the SSD-type detector is likely to be even more effective at detecting neutrons than the current technology. All in all, very good news – let’s hope that Sandia can find a partner to finish development and bring these detectors to market soon.
More contaminated stainless steel
Here’s another story that includes the line “but wait – there’s more” but in this case the “more” is neither encouraging nor surprising. Another batch of metal contaminated with Co-60 has cropped up – this time in the form of pet bowls rather than tissue box holders. But please read on before deciding to feed Fido or Fluffy from the good china! The radiation dose rates in the bowls found to date are vanishingly low – a fraction of what was found in the tissue boxes and only about twice as high as natural background radiation. And with the contamination fixed in the metal it’s highly unlikely to contaminate either your home or the pet food. We can measure it, but that doesn’t make it dangerous.
This may well be another batch of metal products from the same batch of steel (or possibly residual contamination from the same smelter) that contaminated the tissue boxes in January. If so it would hardly be a surprise – remember that steel is made in batches of 50-350 tons and only a tiny fraction of that amount has thus far come to light. It could be that the Indians have tracked it all down, but it could also be that we’ll be seeing mildly contaminated steel for years to come. But we can take heart that – to date – there’s been nothing that’s more than a nuisance, and that nobody can be harmed by what we’ve seen. And – the silver lining – it should be heartening that we are picking these items up! If we are finding objects that have elevated radiation levels but that pose no health risk then it speaks well for our ability to pick up anything genuinely hazardous. Don’t get me wrong – I’d rather have NO contamination in consumer products. But at least our detection systems seem to be passing these informal tests.
Another polonium murder?
Finally (for this week) one more snippet – news stories suggesting that Palestinian leader Yasser Arafat might have been poisoned with polonium in 2004, two years before the Russian Alexander Litvenenko met the same fate. If true this could open a whole can of worms as people try to figure out who did what – but that’s beyond the scope of my expertise. Instead, let’s take a quick look at what might have been found and how plausible the story is.
A number of media stories have picked this up but they are woefully scant with the scientific facts. What I’ve been able to glean is that – for reasons not made clear – a Swiss physician tested some of Arafat’s clothing for radioactivity and found traces of Po-210 in the underwear and some other clothing. One story goes on to state that radioactivity in the amount of several mBq (milli-Becquerels) was found in one article of clothing and stated that this equated to a multiply-lethal dose of radiation.
First – there is no doubt that polonium can kill. The world saw this in 2006 with Litvenenko and anybody else given the same dose of polonium would have suffered the same fate. So we can check that box “yes.”
Second – it is remotely possible that sufficient polonium would have remained in Arafat’s clothing to be detected today. But it is a remote possibility due to the short half-life (about 138 days) of Po-210. Consider – every half-life sees the amount of radioactivity drop by a factor of two. If we round off to make the math easy this means that on New Year’s Eve of 2012 the amount of Po-210 is reduced to an eighth of what it was the previous New Year’s Eve. After two years we’re down to an eighth of an eighth – less than 2% of what we started with. After 8 years the amount of radioactivity in Arafat’s clothing would be less than a ten-millionth of what there was at the time he died. So to discover, say, 20 mBq today means that there would have been 200 kBq (about 6 microCuries) at the time he died – this is on the order of what is sometimes administered to nuclear medicine patients for diagnostic testing and far more than what Litvenenko was dosed with. So for there to be easily detectable Po-210 in any of Arafat’s effects today means that he had to have been given a whopping dose of polonium at the time of his death – and that this had to have gone undetected until today.
Arafat’s symptoms at the time of his death are equivocal – some could be consistent with radiation sickness but others not so much. But in particular, Litvenenko lost every hair on his body by the time he died – polonium is attracted to hair follicles. But this fate did not seem to befall Arafat, casting some doubt on this hypothesis.
The bottom line is that it’s going to be hard – even with an exhumation and examination of Arafat’s body – to conclusively identify polonium poisoning as a cause of death. In large part this is because the inexorable physics of radioactive decay, coupled with the time lag, works against us. But whatever is determined, we can bet the determination will be controversial. So stay tuned!