Synchrotron radiation - Synchrotron radiation

It was discovered in 1947 that electrons orbiting inside a synchrotron generate electromagnetic waves, hence the name synchrotron radiation (SR) or orbital radiation (SOR), but in recent years in Japan it is often simply called synchrotron light. When a charged particle moving at a relativistic speed bends its orbit while being subjected to centripetal acceleration due to a magnetic field, SR is emitted in the tangential direction. SR has been observed on Earth from the bending electromagnets of accelerators, and in space from the strong magnetic fields of neutron stars. When accelerating charged particles to obtain high energy, the energy loss due to SR (proportional to the fourth power of the energy) is a serious obstacle, but from the perspective of optical science and X-ray science, SR is an extremely powerful and unparalleled light source. SR is
(1) A continuous light source that covers the gamma ray, hard X-ray, infrared, and radio wave regions.
(2) Strong convergence and high brightness
(3) Its intensity and polarization properties match well with calculations, making it a useful standard light source over a wide wavelength range.
(4) It is a light source that emits nothing but light.
(5) By using an undulator or wiggler as an insertion light source, the brightness can be increased and linearly polarized light, circularly polarized light, etc. can be generated freely.
It has unique features such as the above. X-ray diffraction, X-ray emission analysis, photoelectron spectroscopy, and optical processing technology have not only made overwhelming advances quantitatively due to its extraordinary intensity, but also made revolutionary advances qualitatively, as it has become possible to detect things that were previously impossible. New detection techniques, such as X-ray absorption fine structure, have also been developed on a large scale for the first time with the advent of SR. Synchrotron radiation facilities with electron (or positron) storage rings dedicated to SR are being built one after another, and SR plays a major role in cutting-edge science, with active research being conducted on the determination of the structure of large proteins and nanoscience. In terms of applications, it is also beginning to be used in medical diagnosis (for example, angiography of the heart) and in lithography for ultra-large-scale integrated circuits.

Source: Morikita Publishing "Chemical Dictionary (2nd Edition)" Information about the Chemical Dictionary 2nd Edition

シンクロトロン中を周回する電子が電磁波を発生することを発見した(1947年)ことにちなんで，シンクロトロン放射(光)(synchrotron radiation，SR)，または軌道放射(光)(synchrotron orbital radiation，SOR)とよばれてきたが，近年，わが国では単に放射光という場合が多い．相対論的な速度で運動する荷電粒子が，磁場による向心加速度を受けつつ軌道を曲げるときに，その接線方向にSRを放出する．地上では加速器の偏向電磁石から，宇宙では中性子星の強い磁場によるSRが観測されている．荷電粒子を加速して高エネルギーを得るには，SRによるエネルギー損失(エネルギーの4乗に比例)は重大な障害であるが，光科学，X線科学サイドからは，ほかに類をみないきわめて有力な光源である．SRは
(1)γ線，硬X線領域から赤外，電波領域にわたる連続光源である，
(2)収束性が強く輝度が高い，
(3)その強度・偏光性が計算とよく一致するので，幅広い波長域にわたる標準光源となる，
(4)光以外のものを発しない光源である，
(5)アンジュレーター，ウィグラーといった挿入光源により輝度を上げ，さらに直線偏光，円偏光などを自在に発生できる，
などのユニークな特徴をもつ．X線回折，X線発光分析，光電子分光，光加工技術などは，そのけた違いの強度によって量的に圧倒的な進歩をとげただけではなく，従来，不可能であった検出が可能になったので，質的にも革新的な進歩をとげた．X線吸収微細構造に代表されるあらたな検出技術も，SRの出現によってはじめて大々的に開発された．SR専用の電子(あるいは陽電子)蓄積リングをもつ放射光施設が次々と建設され，SRは最先端科学の主要な一翼を担っており，巨大タンパクの構造決定やナノサイエンスなどの研究が活発に展開されている．応用面では，医療用の診断(たとえば，心臓などの血管造影撮影)や，超LSI用リソグラフィーにも利用されようとしている．

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