Hospitals use antimatter
A PET scan detects pairs of gamma rays produced when positrons — antielectrons — annihilate with electrons in the body.
Established2 min read
Anderson found the positron in cosmic rays in 1932, the same year the neutron turned up. A positron is the electron’s antiparticle: same mass, opposite charge. Meet an electron and both vanish into two photons of 511 keV, sent in opposite directions.
PET injects a molecule tagged with a short-lived positron emitter, often a stand-in for sugar. The tissue that eats the sugar announces itself by those paired flashes. The scanner is a coincidence counter. Antimatter is not a weapon in this building. It is a dye.
Caveats
- The amount injected is tiny and the half-life is minutes to hours. It is not a stockpile.
Sources
- 1Anderson C. D.. The Apparent Existence of Easily Deflectable Positives. Science 76, 1932.