A Pinch of Nuclear Forensics Can Change the Way We View Past Blasts

The mushroom cloud at the Trinity Test Site in New Mexico on July 16, 1945 (Image: AP)
The mushroom cloud at the Trinity Test Site in New Mexico on July 16, 1945 (Image: AP)

A new test developed by scientists at the Los Alamos National Laboratory in New Mexico can potentially alter what we know about the nuclear tests done as a part of the Manhattan Project.

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According to Popular Mechanics, the test involves using just a pinch of dirt. That small amount contains large amounts of information, which scientists used it to determine the true scope of the Trinity Test, the first nuclear detonation conducted by the United States in 1945.

In a paper published by the Proceedings of the National Academy of Sciences, Susan Hanson, a nuclear chemist at Los Alamos and leader on the project, writes that soil can be tested for molybdenum, an element that is created as zirconium, which is used in many nuclear weapons, decays. By detecting the amounts in a soil sample, along with determining the amount of plutonium in the debris, Hanson and her team can determine how large a blast may have been.

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In the case of the Trinity Test, scientists noted that previous measurements were off. Using this test, they estimated the blast to be around 22.1 kilotons, instead of the recorded 21 kilotons.

Using the tests at other blast sites could help researchers to gather more information about these historic events decades after they occurred. It’s like CSI, but with nuclear physics.

The Los Alamos lab has a personal connection to the project, as many of its scientists contributed to the Trinity project in the 1940s. According to the US Department of Energy, their work would ensure the US government that their plutonium bombs were effective. Less than a month later, a plutonium weapon, called Fat Man, was dropped on Nagasaki, Japan.

Watch footage from the blast:

[Popular Mechanics]

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Weekend editor and night person at Gizmodo. More space core than human.

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DISCUSSION

Nice.

Fun facts: The Uranium “Little Boy” bomb was never tested; the first one ever exploded did so over Hiroshima. It was one of only two gun-type bombs ever detonated (the second and last was the W9 warhead of the atomic cannon, tested once in 1953). Lab critical assembly tests known as “ticking the dragon’s tail” assured scientists that the bomb would work; it was significantly over-engineered.

They were much less certain of the Plutonium “Fat Man” implosion bomb; calculations the day before the test showed that it might not work at all. Just prior to detonation physicist Enrico Fermi jokingly offered bets on whether the bomb would destroy just New Mexico, the entire United States, or the whole world by igniting the atmosphere.

The heat of the Trinity blast fused the desert sand into a greenish glassy substance that came to be called “Trinitite”. For a long time you could just pick it up anywhere around the site, but eventually they bulldozed it all up as it’s mildly radioactive. Samples are available online; I have a 1" piece on my Neat Stuff shelf.