Fun Science Facts #2 - Atomic Bananas Traditional Cache
Fun Science Facts #2 - Atomic Bananas
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Difficulty:
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Terrain:
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Size: 
(micro)
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The second in my occasional series based on bizarre science facts. This is one of those obscure little facts that you pick up when you study atomic physics.
Bananas, like many organic objects, contain a level of radioactive isotopes. The major source of radioactivity in most plants is potassium which normally contains about 0.01% of the unstable isotope potassium-40. This isotope has a half life of around 1.25 billion years, so that the activity of natural potassium is about 31 Bq/g. This means that in 1 gram of potassium, about 31 atoms will decay per second.
A banana typically contains around a half a gram of potassium, so it has an activity of around 15 Bq. A single banana does not therefore have a high level of activity, but a truckload of bananas has enough radioactivity to be capable of causing a false alarm on the monitors used to detect possible smuggling of nuclear material at US ports.
Bananas are even used to measure levels of exposure to radiation. The banana equivalent dose (BED) is a nonstandard unit of radiation exposure, defined as the additional dose a person will absorb from eating one banana. The BED is meant to express the severity of exposure to radiation in terms that people can easily understand.
Other foods that are rich in potassium are potatoes, kidney beans, sunflower seeds and nuts. Brazil nuts are especially rich in potassium-40, and they also contain radium. So they can have an activity of up to 444 Bq/kg, five times the radioactivity of bananas.
The actual cache is a micro container, but has a larger outer container. It now has a pen, but it's always safer to BYO Pen.
Additional Hints
(Decrypt)
Ngbzvp onananf fcevat ernql tebja sebz ebpxf
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