Related topics: black holes · radiation · wavelength · protein · laser

Galaxy clusters caught in a first kiss

For the first time, astronomers have found two giant clusters of galaxies that are just about to collide. This observation can be seen as a missing 'piece of the puzzle' in our understanding of the formation of structure ...

The key to unlock bacterial fusion

Most people know Chlamydia as the venereal disease that can cause infertility if left untreated. But for researchers studying the causative agent, Chlamydia trachomatis, it's a bacteria with intriguing properties. Rather ...

PSI imaging helps with rocket launches

Rockets from the European Space Agency (ESA) fly into space with support from the Paul Scherrer Institute (PSI). Imaging carried out at PSI in cooperation with Dassault Aviation ensures the quality of certain components of ...

The satellite with X-ray vision

In the early hours of October 23, 2011, ROSAT was engulfed in the waves of the Indian Ocean. This was the end of a success story that is unparalleled in German space exploration research. The satellite, developed and built ...

Does the gas in galaxy clusters flow like honey?

We have seen intricate patterns that milk makes in coffee and much smoother ones that honey makes when stirred with a spoon. Which of these cases best describes the behavior of the hot gas in galaxy clusters? By answering ...

eROSITA – the hunt for dark energy begins

On 21 June 2019 the Spektrum-Röntgen-Gamma (Spektr-RG / SRG) spacecraft will be launched from the Kazakh steppe, marking the start of an exciting journey. SRG will be carrying the German Extended ROentgen Survey with an ...

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X-radiation (composed of X-rays) is a form of electromagnetic radiation. X-rays have a wavelength in the range of 10 to 0.01 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz (3 × 1016 Hz to 3 × 1019 Hz) and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays. In many languages, X-radiation is called Röntgen radiation after Wilhelm Conrad Röntgen, who is generally credited as their discoverer, and who had called them X-rays to signify an unknown type of radiation.:1-2

X-rays are primarily used for diagnostic radiography and crystallography. As a result, the term X-ray is metonymically used to refer to a radiographic image produced using this method, in addition to the method itself. X-rays are a form of ionizing radiation and as such can be dangerous.

X-rays from about 0.12 to 12 keV are classified as soft X-rays, and from about 12 to 120 keV as hard X-rays, due to their penetrating abilities.

The distinction between X-rays and gamma rays has changed in recent decades. Originally, the electromagnetic radiation emitted by X-ray tubes had a longer wavelength than the radiation emitted by radioactive nuclei (gamma rays). So older literature distinguished between X- and gamma radiation on the basis of wavelength, with radiation shorter than some arbitrary wavelength, such as 10−11 m, defined as gamma rays. However, as shorter wavelength continuous spectrum "X-ray" sources such as linear accelerators and longer wavelength "gamma ray" emitters were discovered, the wavelength bands largely overlapped. The two types of radiation are now usually defined by their origin: X-rays are emitted by electrons outside the nucleus, while gamma rays are emitted by the nucleus.

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