So I was watching an old episode of White Collar where they were trying to fake a bottle of old wine. Then they said something about adding (or was it removing?) Cs-137 to make it look authentic. Can you explain why wine would (or maybe wouldn’t?) have Cs-137 in it?
Wow – this is a really cool topic! It reminds me of a great book I read about counterfeit wine – I think it was called The Billionaire’s Vinegar. But let’s get back to your question.
We get Cs-137 from uranium and plutonium fission, and the very first discovery of fission occurred in the 1930s. Otto Hahn, Fritz Strassmann, Lise Meitner, and Otto Frisch got credit for the discovery – however, it’s likely that Enrico Fermi produced fission several years earlier in experiments for which he won the Nobel Prize. What happened was that Fermi was playing with neutrons, trying to produce trans-uranium elements by bombarding uranium and, sure enough, he saw evidence of new types of radioactive atoms, wrote up his discovery, and collected his prize in 1938.
The problem was that what Fermi had done was to split uranium atoms with the neutrons he was shooting at them and the radioactivity he was measuring was from the radioactive fission products from those fissions. It took a while for all of that to be realized – by then, fission had been produced and written up by the four Germans mentioned earlier. The way it goes in science is that it’s not the first person who sees something who gets credit for the discovery – it’s the first person who realizes what they’ve seen and understands its significance, and Fermi didn’t interpret his discovery correctly. On the other hand, he still earned a Nobel Prize, he is still considered one of the greatest physicists of the 20th century, and in 1942 he supervised the startup of the world’s first nuclear reactor.
The purpose of all of this history is to make the point that, before humans could reliably fission atoms, there was no Cs-137 on Earth[1]. Which means that a bottle of wine purporting to have been filled in, say, 1780 should have no Cs-137; finding this nuclide in a bottle of purported antique wine automatically proves it’s modern – and fake. Even better, since Cs-137 emits gamma radiation that can penetrate the wine and glass, the check can be done without even opening the bottle! The problem is that a wine bottled in, say, 1930 won’t have any Cs-137, but it’s also not nearly as old as what some of the highest-price fakes purport to be. So seeing Cs-137 rules out any bottle of wine that’s claimed to have been made before the mid-1930s, but failing to see it does not prove that a wine is centuries old. Having said that, this method is still remarkably useful and it’s uncovered a lot of what would have turned out to be a hideously expensive fake.
The thing is that there’s not a lot of Cs-137 in nature – I’ve seen it in sediments I’ve surveyed in central Ohio, Upstate New York, and in Japan after the Fukushima accident, but never in large quantities. It primarily comes from the atmospheric nuclear weapons testing in the 1940s, 50s, and 60s, but most has decayed away by now, so concentrations are low. To count these samples, then, requires taking them deep underground and surrounding them with lead to reduce background radiation to a faint whisper of what we normally see. And this calls for using old lead – lead that was dug out of the ground and formed before the first nuclear explosion on July 16, 1945 to prevent contamination of the lead with radioactivity. And one such counting chamber I worked with a while back even sheathed the lead with steel from a pre-WWII battleship.
The reason for going to these extremes is that there is always natural background radiation, and it puts limits on the sensitivity of our radiation instruments. Explaining why gets into a discussion of counting statistics, and I wouldn’t inflict that on anyone lightly. Think of it this way – if I’m shining a searchlight in your eye, how likely is it that you’ll notice someone lighting a match? Not very likely, because the light of a single match will be drowned out by the glare from the searchlight. But as I saw in Mammoth Cave a year or so back, a single match in an absolutely dark cavern can let you see for hundreds of feet. Or, to put it another way, to see a dim source of light you need to be in a very dark place. Similarly, to detect vanishingly small traces of radioactivity your instrument and sample need to be in a place that’s radiologically “dark” – a place from which background radiation is excluded.
So there you go! Why we look for Cs-137 in antique wines, how we manage to find such trace amounts of it, and even a little bit about scientific, geologic, and atomic history! Oh – and the show you’re thinking about is Bottlenecked, from White Collar, season 1, episode 12.
[1] Well…with a caveat. Previously I’ve written about the natural nuclear reactor in what is now Oklo in the African nation of Gabon. About two billion years ago a natural uranium deposit achieved a self-sustaining chain reaction (i.e. criticality), producing an array of fission products, including Cs-137. The reactor operated for about 100,000 years before running out of fuel and shutting down. The thing is, Cs-137 has a half-life of only 30 years, so it had all decayed away within a few millennia and it was long, long gone by the time humans started making wine.