Scientists Find New Kind Of Crystal In Debris From Trinity Nuclear Test

Scientists Find New Kind Of Crystal In Debris From Trinity Nuclear Test

Forbes·2021-05-19 14:00

This photo taken at eighteen seconds past the moment of Gadget's initial detonation at 5:29:45 a.m. ... [+] shows the tremendous flash of light and smoke rings in the early morning sky. (Photo by © CORBIS/Corbis via Getty Images)Corbis via Getty ImagesThe dawn of the nuclear age spawned a new kind of matter, and scientists just discovered a piece of it.When the worlds first nuclear weapon exploded on July 16, 1945 in the desert outside Alamogordo, New Mexico, it vaporized the test tower that had held the bomb, blasted a 80-meter wide crater in the desert floor, and fused the sand into a layer of glass 2cm thick for 300 meters in every direction. The world had never seen so much destructive power.And 75 years later, were still finding surprises amid the debris of that first nuclear blast, the Trinity test. When the bomb exploded, its fireball swept up nearby sand and fused it into lumps of glass and crusty fused material, which then rained down from the sky. Most of that clumpy, part-glass and part-crust stuff is pale green, and its been nicknamed trinitite, in honor of the nuclear test that created it.Some trinitite, however, includes bits of the test tower or the copper cables that once connected cameras and microphones set to watch the explosion. All that copper tinted the resulting glassy substance red. And a recent study of a sample of red trinitite reveals that not only did the force of the worlds first nuclear blast melt sand into glass and vaporize human-made metals, it warped and fused those materials into a strange crystal that breaks some of the usual rules of how crystals are supposed to work.The Strange Byproduct Of CataclysmCrystals, from snowflakes to table salt to diamonds, are all about order and symmetry. They form because atoms arrange themselves in a 3D pattern that repeats over and over. Each repetition of that pattern is called a cell, and the cells that make up each crystal have to fit together so neatly that there are no gaps between the edge of one cell and the next.That need for extreme order limits the number of possible ways a crystals lattice of atomic cells can organize themselves. To describe that properly, we need to think about symmetry for a minute.Imagine a shape: maybe its a square, a five-pointed star, or a large X. How many ways can you divide that shape and still get identical pieces? If the answer is 3, which is what youd get with an equilateral triangle, then the object has 3-fold symmetry. If its 6, as in the case of a Star of David, the object has 6-fold symmetry. Of course, anything that has 6-fold symmetry also has 3-fold symmetry and 2-fold symmetry.A normal crystal what physicists call a periodic crystal might have 2-, 3-, 4-, or 6-fold symmetry. But some kinds of symmetry, like 5-fold and 7-fold, are totally out of the question. It simply isnt done.But under the right circumstances, by which I mean genuinely terrifying amounts of sudden heat and pressure, atoms can atoms can be forced to line up in unusual ways, creating something thats technically a crystal, but breaks those rules of symmetry.Theyre called quasicrystals, and so far scientists only know of about 100 of them. Most of those have been produced in labs with shock synthesis experiments, but at least three have also turned up in the remains of a meteorite. The implication is that it takes a lot of force to bend the laws of physics and forge a whole new kind of material. Quasicrystals are the strange byproduct of cataclysm.This lump of red trinitite contains sand from the desert floor, fused with copper from cables ... [+] vaporized by the bomb.Bindi and Steinhardt 2021Shock PhenomenaA few years ago, physicsts Paul Steinhardt of Princeton University and Luca Bindi of the University of Florence formed part of the team of scientists that identified quasicrystals in a meteorite found in Khatarka, Russia. They managed to create the same quasicrystal in the lab with shock experiments, which proved that the strange new material was born of tremendous heat and pressure.This naturally led to the question: could there be quasicrystals lurking in remnants of other shock phenemona, such as an atomic blast? said Steinhardt. When Bindi ran across a scientific paper describing red trinitite, the team realized that its mixture of fused sand and human-made materials could be the perfect recipe for novel forms of matter like quasicrystals.All our searches together have been longshots, and this seemed like a longshot too," admitted Steinhardt. "But we have learned over time that we pursue every idea, even if it seems like a longshot.Bindi and Steinhardt managed to get hold of a small chunk of red trinitite which someone had picked up from the sands of Alamogordo Bombing Range a few months after the Trinity test. By measuring gamma rays from the decay of a particular radioactive element (Europium-152), they were able to tell how much radiation the chunk of trinitite had been exposed to during the nuclear blast. And that, in turn, suggested how close to Ground Zero it had been when the bomb dropped.The red trinitite appears to have been created about 55 to 60 meters from ground zero, close to where the coaxial cable from the top of the tower terminated in a trench, they wrote.Their sample contained several roundish blobs of metals, mixed in with the glassy fused sand but not quite blended fully like the chocolate chips in a cookie. Bindi and Steinhardt focused on one metallic blob in particular. By measuring how X-rays reflected off the blob, the physicists were able to learn which elements it was made of and how they were arranged.Embedded in a blob of metal melted into a chunk of red trinitite, Bindi and Steinhardt found a 20-sided crystal made of silicon, copper, calcium, and iron all arranged in a way they had never seen before. The tiny 10-micrometer-wide crystal had the two- and three-fold symmetry you might expect in any crystal, but it also had five-fold symmetry, which flies in the face of the usual rules. The force of the Trinity test had forged a new quasicrystal.Indelibly Etched In HistoryThe trinitite crystal is unusual for a number of reasons, even among quasicrystals.Of the 100 or so quasicrystals that scientists have identified so far most of them created in high-intensity lab experiments most dont hold themselves together for very long at what wed consider normal temperatures and pressures. You usually cant slam two rocks together at high speed in the lab, create a cool new quasicrystal, and then put it on your mantle for display, because without the high temperatures and pressures that formed them, most quasicrystals settle into some other, less bizarre form. But this one has been stable for more than 75 years.Its also the first quasicrystal scientists have found which is mostly made up of silicon, and the only one that combines silicon, iron, and copper. That discovery has prompted Bindi and Steinhardt to think about other places scientists could go prospecting for quasicrystals.This new study made me think that quasicrystals could be much more [common] than thought," Bindi said.Outside the lab, natural phenomena like meteor impacts and even lightning strikes could produce the "transient extreme-pressure temperature conditions" needed to make quasicrystals. And those phenomena, according to Bindi and Steinhardt, often force together four or more elements like the ones in the trinitite quasicrystal. Lab experiments don't often explore those multi-element combinations, but Steinhardt and Bindi suggest that "Quasicrystals may be more common when there are more components."By examining meteor craters, tektites, lunar surface samples, and fused sand and soil called fulgurites left behind by lightning strikes, they suggest that scientists could discover more new quasicrystals and start to understand more about how they form.There are metallic materials in several shocked meteorites with usual chemical compositions, that were never checked from a structural point of view," Bindi said. "I think an open-mind approach could reveal surprises. Great discoveries can only happen if we'll look at things differently."Nuclear detonation sites, like Trinity and the many others that litter the western U.S. and several Pacific islands, could also yield new quasicrystals. And someday, if scientists manage to identify enough quasicrystals that form during nuclear explosions and learn enough about exactly which processes form which crystals they could serve as tiny crystalline fingerprints to help international agencies monitor for signs of nuclear testing.As the sample set grows, it would become a useful independent diagnostic, said Steinhardt. Thats long in the future, of course. For now, Bindi, Steinhardt, and their colleagues plan to try to reproduce the trinitite quasicrystal in the lab of collaborator Paul Asimow. That will help them confirm that its the product of a really big impact, and understand the mechanical details of its formation.Meanwhile, the trinitite quasicrystal holds the unusual distinction of being the oldest known human-made quasicrystal, with the distinctive property that its precise time of creation is indelibly etched in history.


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