Как по Английски будет античастица

noun

A subatomic particle having the same mass as a given particle but opposite electric or magnetic properties. every kind of subatomic particle has a corresponding antiparticle, e.g. the positron has the same mass as the electron but an equal and opposite charge.

Примеры использования:

Positively charged beta particles, the antiparticle of electrons, are called positrons.