So if one positron was going to blow up Evanston, how does my cardiologist do positron emission tomography?
From Wikipedia, for those who might be interested:
“Perhaps the best known naturally occurring radioisotope which produces positrons is potassium-40, a long-lived isotope of potassium which occurs as a primordial isotope of potassium. Even though it is a small percentage of potassium (0.0117%), it is the single most abundant radioisotope in the human body. In a human body of 70 kg (150 lb) mass, about 4,400 nuclei of 40K decay per second.[35] The activity of natural potassium is 31 Bq/g.[36] About 0.001% of these 40K decays produce about 4,000 natural positrons per day in the human body.[37] These positrons soon find an electron, undergo annihilation, and produce pairs of 511 keV photons, in a process similar (but much lower intensity) to that which happens during a PET scan nuclear medicine procedure.”
If the author of that piece is worried about positrons, he might want to stay away from bananas - they’re full of potassium, the radioactive isotopes of which are merrily spewing out positrons as they undergo decay on your kitchen counter.
“So if one positron was going to blow up Evanston, how does my cardiologist do positron emission tomography?”
Just a bit over the top. It might take out the contraption it is held in and probably damage the lab room it is in and possibly anyone too close. I suspect the city is safe.
“ So if one positron was going to blow up Evanston, how does my cardiologist do positron emission tomography.?
The article is about an antiproton, not a positron. Still, it would not release a terrible amount of energy when annihilated with a proton. Now take a gram of each, you’d get about 32 kilotons TNT equivalent.