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Two new probable gravitational waves—ripples in the fabric of spacetime caused by cataclysmic cosmic events and first predicted by Albert Einstein over 100 years ago—have been detected by the Laser Interferometer Gravitational-Wave ...

Watching molecules split in real time

Using a new X-ray technique, a team of researchers was able to watch in real time as a molecule split apart into two new molecules. The method could be used to look at chemical reactions that other techniques can't catch, ...

Catalyst renders nerve agents harmless

A team of scientists including researchers at the U.S. Department of Energy's (DOE) Brookhaven National Laboratory has studied a catalyst that decomposes nerve agents, eliminating their harmful and lethal effects. The research ...

Direct imaging of active orbitals in quantum materials

In quantum materials based on transition metals, rare-earth and actinide elements, electronic states are characterized by electrons in orbitals d and f, combined with the solid's strong band formation. Until now, to estimate ...

CubeSats prove their worth for scientific missions

Only a few years ago, the astronomy and heliophysics communities were skeptical about whether CubeSats could reliably obtain scientific data. But these breadloaf-size satellites have proven their ability to return useful ...

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X-ray

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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