Protonium is a type of exotic atom in which an antiprotonorbits a proton or a proton orbits an antiproton. Because it contains both matter and antimatter, protonium is called a type of "mass" instead of a type of "matter."
These exotic atoms are made in particle acceleratorlaboratories by making an antiproton come to rest near a proton, thus causing one to orbit the other. The result is an exotic atom that exists for a fraction of a second before the particles annihilate each other. This form of mass allows scientists to directly measure the mass of antiprotons, which are very close to that of protons. The masses are quite similar, but it is unknown if they are exactly the same.
Protonium is named after the subatomic particles which comprise it, similar to neutronium, which is composed of neutrons. Similarly, there is pionium, muonium, and other forms of mass that are made of very exotic particles.
This undeflected protonium, if formed, would be allowed to traverse a meter of high vacuum, within which it is expected to decay.
Unlike the hydrogen atom in which the dominant interactions are due to the charge of the electron and the proton, the constituents of the protonium interact dominantly through the strong interactions.
Pionium, ie, a bound state of two oppositely charge pions are interesting from the point of view of exploration of the strong interaction.
However, the true analogues of the positronium in the theory of strong interactions are the quarkonium states made of heavy quarks such as the charm or bottom (top quarks are so heavy that they decay through the weak force before they are able to bind).
Understanding bound states of hadrons such as pionium and protonium are also important in order to clarify notions related to hadronic exotic (hadron)s such as mesonic molecules and pentaquark states.
Feeds |
Contact