X-ray
hideX-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.
For more information about X-ray, read the full article at
Wikipedia.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.
News tagged with x rays
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Dec 22, 2009 |
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From their humble beginnings as offshoots of the ordinary electric light bulb, particle accelerators have evolved in surprising directions. Among the most productive and promising developments have been light ...
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Voyager makes an interstellar discovery
Space & Earth / Space Exploration
23 hours ago |
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The solar system is passing through an interstellar cloud that physics says should not exist. In the Dec. 24th issue of Nature, a team of scientists reveal how NASA's Voyager spacecraft have solved the mystery.
As shuttle's career nears an end, NASA turns focus to satellites
Space & Earth / Space Exploration
Dec 26, 2009 |
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NASA heads into 2010 with the bittersweet assignment of retiring the space shuttle after nearly three decades. But that's not all the agency has planned: There are also launches of three new satellites aimed at better understanding ...
Critical protein helps mend damaged DNA
Dec 24, 2009 |
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In order to preserve our DNA, cells have developed an intricate system for monitoring and repairing DNA damage. Yet precisely how the initial damage signal is converted into a repair response remains unclear. Researchers ...
Tiny nano-electromagnets turn a cloak of invisibility into a possibility
Dec 22, 2009 |
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A team of researchers at the FOM institute AMOLF (The Netherlands) has succeeded for the first time in powering an energy transfer between nano-electromagnets with the magnetic field of light.
Imaging tests identify role of allergies in chronic sinus disease
Dec 21, 2009 |
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Exposing patients with chronic sinus disease to allergens and then obtaining repeated images by X-ray or ultrasound reveals that nasal allergies may be involved in some cases of chronic sinus disease, according to a report ...
Silicon technology offers extended X-ray vision of high-energy cosmos
Space & Earth / Space Exploration
Dec 21, 2009 |
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(PhysOrg.com) -- As elements of the integrated circuits running our computers, phones and electronics, silicon wafers are everywhere. An ESA-led effort is establishing an out-of-this-world use for these ...
Next generation lens promises more control
Dec 20, 2009 |
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(PhysOrg.com) -- Duke University engineers have created a new generation of lens that could greatly improve the capabilities of telecommunications or radar systems to provide a wide field of view and greater ...
Scientists take a step towards uncovering the histone code
Dec 20, 2009 |
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Researchers at Emory University School of Medicine have determined the structures of two enzymes that customize histones, the spool-like proteins around which DNA coils inside the cell.
War-torn 'nursery' hopes to send monkeys to Mars
Space & Earth / Space Exploration
Dec 20, 2009 |
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The monkeys at this run-down research centre which was once the pride of Soviet science have seen it all -- a brutal civil war, freezing winters and starvation.
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