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

Modeling a core collapse supernova

Stars greater than eight solar-masses end their lives spectacularly—as supernovae. These single-star supernovae are called core collapse supernovae because when their dense cores (at this stage composed primarily of iron) ...

Evidence found for cloaked black hole in early universe

A group of astronomers, including Penn State scientists, has announced the likely discovery of a highly obscured black hole existing only 850 million years after the Big Bang, using NASA's Chandra X-ray Observatory. This ...

The mechanism for gamma-ray bursts from space is decoded

Gamma-ray bursts, short and intense flashes of energetic radiation coming from outer space, are the brightest explosions in the universe. As gamma rays are blocked by the atmosphere, the bursts were discovered accidentally ...

First pictures of enzyme that drives new class of antibiotics

Understanding how antibiotic scaffolds are constructed in nature can help scientists prospect for new classes of antibiotics through DNA sequencing and genome mining. Researchers have used this knowledge to help solve the ...

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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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