synchrotrons

Synchrotrons are a class of cyclic particle accelerators in which charged particles, typically electrons, are steered by magnetic fields along a closed path and boosted to near-light speeds by radiofrequency cavities. As the particles are bent along the curved trajectory, they emit electromagnetic radiation known as synchrotron radiation. In storage rings, the circulating beam can be stored for hours, with the emitted light extracted from beamlines for experiments.

Operation involves injecting particles into a linear or circular accelerator, then guiding them into a closed ring. RF cavities provide acceleration, bending magnets steer the beam, and focusing magnets keep it tight. In many facilities, insertion devices placed in straight sections—undulators and wigglers—enhance brightness and tailor the spectrum of the emitted light.

Synchrotron radiation is extremely bright, highly collimated, and spans a broad spectrum from infrared to hard X-rays. Its brightness, coherence, and tunable wavelength enable high-resolution imaging, spectroscopy, and diffraction experiments. The light can be polarized and its wavelength adjusted by changing the accelerator energy and the configuration of insertion devices.

Facilities and configurations vary, but modern light sources include third-generation storage-ring synchrotrons and, in some cases, free-electron lasers. Third-generation sources use insertion devices to generate intense, tunable beams; some facilities also offer ultra-short-pulse capabilities through FELs or specialized beamlines.

Applications of synchrotrons span materials science, biology, chemistry, physics, environmental science, and medicine. Common techniques include X-ray diffraction, spectroscopy, and imaging, enabling studies at micron or sub-micron scales and at high temporal resolution.

History traces the observed synchrotron radiation to the mid-20th century, followed by rapid development of dedicated light sources from the 1960s onward. Today, synchrotrons provide powerful photon beams for a broad range of scientific investigations.