History of synchrotron X-rays

X-rays were discovered in 1895, and synchrotron X-rays were first observed in 1947. Initially synchrotron X-rays were considered an undesirable effect, but in the 1960s they began to be recognised as an exceptional tool.

In 1895, W.C. Röntgen discovered mysterious rays capable of passing through the human body. Because of their unknown nature, he called them X-rays.
In 1912, M. von Laue and P. Knipping obtained the first diffraction pattern of a crystal using X-rays.
In 1953, the structure of DNA was solved by J. Watson, a biologist, and F. Crick, a physicist, thanks to the use of X-rays.

Although these results were remarkable, the X-ray tubes were limited: the light was emitted in all directions, with no possibility of focusing it or making the rays parallel. This light was also only intense at particular wavelengths, which restricted its use, particularly in the field of spectroscopy.

 Rontgen's X-ray of a hand with ring

One of Roentgen's first X-ray photographs: hand with ring.

An alternative source of X-rays grew out of work on particle accelerators. The first accelerators (cyclotrons) were built by particle physicists in the 1930s. In these machines, the nucleus of the atom was split using the collision of high-energy particles. From the results of these collisions the physicists tried to deduce the laws of fundamental physics that govern our world and the whole of the universe.

Synchrotron radiation was seen for the first time at General Electric in the United States in 1947 in a different type of particle accelerator (synchrotron). It was first considered a nuisance because it caused the particles to lose energy, but it was then recognised in the 1960s as light with exceptional properties that overcame the shortcomings of X-ray tubes.

In the mid- to late 1970s, scientists began to discuss ideas for using synchrotrons to produce extremely bright x-rays. These discussions led to the construction in the late 1980s and early 1990s of the ESRF and shortly thereafter two other “third-generation” synchrotrons (the Advanced Photon Source in the United States and SPring-8 in Japan). Impressive progress continues to be made in accelerator physics, electronics and computing as well as in magnet and vacuum technologies, with the goal of producing even brighter and more stable X-ray beams.

General Electric 1947 synchrotron

Scientists around the vacuum chamber of a 1947 General Electric synchrotron (photo courtesy of NSLS, Brookhaven).

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