If you have ever eaten a banana, then you have consumed an active radiation source. They are rich in potassium, a small fraction of which is the naturally occurring radioactive isotope ⁴⁰K (potassium-40). While this might sound scary, the levels are safe for human consumption, and they have a fun side effect: neutrinos. Beta decay, one of the ways unstable atoms can undergo radioactive decay, converts the potassium into calcium with a side helping of elementary particles: an…