U.S. Department of Energy

Pacific Northwest National Laboratory

Glossary

A | C | D | E | H | L | N | O | P | S | T | W
Accelerator-based experiments

Physicists probe nuclei with complex devices called accelerators. Cosmic accelerators produce particles with much higher energies than can be produced by particle accelerators on Earth. Studying these particles may give physicists a way of exploring energy scales far beyond what current or future particle accelerators can achieve.

Antimatter

What we know about the history of the cosmos suggests that visible matter could have been destroyed by an equal amount of antimatter long before the present day. Explaining why this did not occur, and therefore, why the cosmos as we know it exists, is a fundamental question scientists are researching.

Antiparticle

A subatomic particle identical to another subatomic particle in mass, but opposite to it in electric and magnetic properties (as sign of charge) that when brought together with its counterpart produces mutual annihilation. A subatomic particle not found in ordinary matter.

Astrophysics

The science of why objects, usually stellar and galactic processes, behave the way they do.

Axions

A subatomic particle of low mass and energy that is postulated to exist by the Peccei-Quinn theory in 1977 because of certain properties of the strong force. The axion originally arose as part of an elegant solution to the “strong CP problem” (charge conjugation and parity) in the Standard Model of particle physics. It was then appreciated that a light axion is an ideal cold dark matter candidate.