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
Carbon Atmosphere Discovered on Neutron Star
Nov 04, 2009 |
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(PhysOrg.com) -- Evidence for a thin veil of carbon has been found on the neutron star in the Cassiopeia A supernova remnant. This discovery, made with NASA's Chandra X-ray Observatory, resolves a ten-year ...
X-ray named top achievement by British museum
Nov 04, 2009 |
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The X-ray was named the most important modern scientific achievement Wednesday in a poll conducted for Britain's Science Museum, beating Apollo spacecraft and DNA.
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Mysterious X-rays from a Nearby Galaxy
Nov 13, 2009 |
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(PhysOrg.com) -- The nucleus of an active galaxy, an AGN, contains a massive black hole that is vigorously accreting material. In the process it typically ejects jets of particles and radiates brightly at ...
Starburst galaxy sheds light on longstanding cosmic mystery
Nov 02, 2009 |
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(PhysOrg.com) -- An international collaboration that includes scientists from the University of Delaware's Bartol Research Institute in the Department of Physics and Astronomy has discovered very-high-energy ...
Fermi Telescope Detects Gamma-Ray From 'Star Factories' in Other Galaxies
Nov 02, 2009 |
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Nearby galaxies undergoing a furious pace of star formation also emit lots of gamma rays, say astronomers using NASA's Fermi Gamma-ray Space Telescope. Two so-called "starburst" galaxies, plus a satellite ...
Research sheds new light on neutron stars (w/ Video)
Nov 02, 2009 |
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(PhysOrg.com) -- Research by Michigan State University scientists has shed new light on the properties of neutron stars, galactic oddities that are formed when a large star runs out of fuel and collapses.
Study: CT scans rule out heart attacks faster
Nov 18, 2009 |
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(AP) -- A new study suggests that a type of "super X-ray" can give a faster, cheaper way to tell whether a chest pain sufferer is really having a heart attack.
Sharks under threat as environmental change bites hard
Nov 17, 2009 |
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(PhysOrg.com) -- Their size and fearsome appearance have made them the stuff of nightmares, but new research just published suggests that sharks may not be as tough as they appear.
Swift, XMM-Newton satellites tune into a middleweight black hole
Nov 10, 2009 |
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(PhysOrg.com) -- While astronomers have studied lightweight and heavyweight black holes for decades, the evidence for black holes with intermediate masses has been much harder to come by. Now, astronomers ...
Fermi Telescope Peers Deep into Microquasar (w/ Video)
Nov 27, 2009 |
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(PhysOrg.com) -- NASA's Fermi Gamma-ray Space Telescope has made the first unambiguous detection of high-energy gamma-rays from an enigmatic binary system known as Cygnus X-3. The system pairs a hot, massive ...
Proton therapy is well-tolerated in prostate cancer patients
Nov 02, 2009 |
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Proton beam therapy can be safely delivered to men with prostate cancer and has minimal urinary and rectal side effects, according to a study presented November 2, 2009, at the American Society for Radiation Oncology's 51st ...
Acute heart attack patients receiving high ionizing radiation dose
Nov 16, 2009 |
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Acute heart attack patients received an average total dose of ionizing radiation equal to 725 chest X-rays from medical tests during their hospital stay, according to research presented at the American Heart Association's ...
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