A method for tracing the origin of uranium cubes believed to have gone missing since the end of World War II could help law enforcement agencies to prevent the illicit trafficking of nuclear materials. Reported by New Scientist.
During the Second World War, there was a race in the development of nuclear technology, the United States also participated in it, because they feared that Germany would be the first in the world to become the owner of a new generation of weapons of mass destruction. The Nazis had two nuclear weapons programs. One of them involved the creation of a test nuclear reactor. Initially, the research group that developed the reactor was based in Berlin. In 1945, scientists led by the creator of quantum mechanics and Nobel Prize winner in physics Werner Heisenberg arrived in
town
Haigerloch
where the last experiment was carried out. The installation consisted of 664 cubes of uranium with a total weight of 1525 kilograms, they were surrounded by a graphite moderator-reflector of neutrons weighing 10 tons.
Another German researcher, Kurt Diebner, worked in another experimental laboratory and developed a scheme for a nuclear explosive device in the form of an explosive ball, inside which were cubes of uranium.
When the Haigerloch laboratory was captured by American and British forces in 1945, more than 600 cubes of uranium were shipped to the United States. Some of the bricks were probably used in American nuclear weapons development, while others are now owned by collectors and research institutions. However, hundreds of cubes from Diebner's laboratory were missing. Until recently, their search was difficult.
In this regard, scientists presented at a meeting of the American Chemical Society a new way to identify Nazi uranium cubes. In this they were helped by one cube, which is stored at the Pacific Northwest National Laboratory (PNLL) in the United States. Dr Jon Schwantes, who led the new study, noted that no one knows exactly how the cube ended up in the institution. The team has also worked with the University of Maryland, which has access to several other cubes.
The scientists turned to radio chronometry, a nuclear version of the method that geologists use to age carbon samples based on the radioactive isotope content. The principle is also similar to the method of determining the historical period of artifacts, which is used in archeology.
“When the cubes were first cast, they contained fairly pure uranium. Over time, radioactive decay converted some of the uranium into thorium and protactinium, ”the scientists explained.
Researchers have adapted a radio chronometry procedure to separate and evaluate these elements in a PNNL cube and have developed a method that determines their relative concentrations and shows how long ago the cube was created. Based on this, scientists will be able to understand whether the cube under study was produced in Germany during World War II or in the United States after 1945.
It is emphasized that this method, if improved, will allow the analysis of rare-earth impurities in the cube, showing where the original uranium was mined, which would indicate whether it was produced for the Heisenberg group or the Diebner group. However, the main achievement of scientists is that their investigation of Nazi uranium can be useful to law enforcement – they believe that their developments will help stop nuclear smuggling.
