[The world underwent a profound transformation when project scientists in Manhattan detonated the first atomic bomb on July 16, 1945.
The Trinity test created a radioactive legacy, much like the numerous ground nuclear tests that followed (with a total of 528 explosions), which introduced radioactive particles into the atmosphere.
As a result, the air we breathe now carries a slight level of radioactivity. This has led to unforeseen effects on various materials we produce.
For instance, steel is manufactured by pushing refined oxygen through molten iron ore. Given the radioactivity present in today’s air, the steel produced is subtly radioactive as well.
The fallout from nuclear tests reached its peak in 1963, with levels subsequently dropping over 95% as the radioactive particles in the atmosphere decreased. This decline occurred gradually.
While the steel produced today poses no health risks, its slight radioactivity can interfere with sensitive scientific instruments, particularly those designed for detecting dark matter.
Hence, scientists are on the lookout for materials with minimal radiation contamination. Steel made before the first nuclear explosion in 1945 is particularly valuable for particle physics research because it contains significantly fewer radioactive particles.
Much of this “low-radiation steel” has been salvaged from shipwrecks, including a fleet of 52 German battleships that sank in the shallow waters of Orkney, Scotland.
However, the rising demand for low-radiation steel has sparked controversy. In 2017, it was revealed that salvage divers had illegally looted up to 40 World War II warships near Singapore, Indonesia, and Malaysia.
This discovery triggered protests from veterans and historians, who regard these wrecks as sacred sites of underwater warfare.
Ancient Roman lead is also prized among physicists for its ability to shield ultra-sensitive experiments from background radiation. Naturally radioactive, lead ore can contain trace amounts of isotope lead 210, which has a half-life of 22 years.
While fresh lead suitable for particle physics takes centuries to produce, Roman-sourced lead had enough time to lose its radiation.
In 2010, Italy’s National Archaeological Museum celebrated a historic agreement to donate 120 lead ingots, recovered from a Roman ship that sank around 80-50 BC, to the Nuclear Physics Institute for use in future experiments.
This article answers the question posed by Henry Becker from Durham: “How does background radiation affect particle detectors?”
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