A directional stream of particles or radiation, such as X-rays.A beam is a directional stream of particles or electromagnetic radiation, such as X-rays, that travels in a roughly straight line. Beams are fundamental to many areas of physics and technology, from the light beams in optical fibers to the particle beams in accelerators. In astrophysics, beams of X-rays are emitted by some of the most energetic objects in the universe, such as neutron stars and black holes, often as jets of matter accelerated to near-light speeds. The study of beams allows scientists to probe the properties of matter and radiation in extreme conditions.
The concept of a beam has been used since the early studies of optics, but the modern understanding of particle beams emerged in the 20th century with the development of particle accelerators and X-ray technology.
A beam is created when particles or waves are collimated, meaning their trajectories are aligned to be nearly parallel. This can be achieved through various mechanisms, such as focusing with lenses or magnets, or by the natural geometry of the source. For example, in an X-ray tube, electrons are accelerated and directed at a metal target, producing X-rays that are then collimated into a beam. In particle accelerators, magnetic fields steer charged particles along a defined path, creating a beam that can be used for collisions or experiments.
Beams are used in countless applications, including medical radiation therapy, materials analysis, and particle physics experiments, as well as in everyday devices like laser pointers and microwave transmitters.
The most powerful particle beams, such as those at the Large Hadron Collider, can carry enough energy to melt a ton of copper if focused on a small spot.
