antiprotones
An antiproton (symbol p̄ or "p-bar") is the antiparticle of the proton: it has the same mass and spin as a proton but opposite electric charge and baryon number. Like all antiparticles, when an antiproton encounters its corresponding particle (a proton) they annihilate, producing other particles such as pions and photons.
Antiprotons were first observed in 1955 by Emilio Segrè and Owen Chamberlain during experiments at the Lawrence
Experimental facilities such as CERN’s Antiproton Decelerator create, slow and store antiprotons for research. Techniques like
Research with antiprotons tests fundamental symmetries (notably CPT symmetry), measures intrinsic properties (mass, charge-to-mass ratio, magnetic