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X-rays are produced by interaction of accelerated electrons with tungsten nuclei within the tube anode. Two types of radiation are generated: characteristic radiation and bremsstrahlung (braking) radiation. Changing the X-ray machine current or voltage settings alters the properties of the X-ray beam. X-rays are produced within the X-ray ...
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X-rays are produced de novo when needed; No radioactive...
- Tutorial Introduction
X-rays are produced de novo as needed; No radioactive...
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Oct 10, 2021 · At the anode, electrons can interact with the atoms of the anode in several ways to produce x-ray photons. Outer shell interaction: low energy EM released and quickly converted into heat energy. Inner shell interaction: produces characteristic radiation. Nucleus field interaction: aka Bremsstahlung.
- Overview
- Production of X-rays
- Detection of X-rays
There are three common mechanisms for the production of X-rays: the acceleration of a charged particle, atomic transitions between discrete energy levels, and the radioactive decay of some atomic nuclei. Each mechanism leads to a characteristic spectrum of X-ray radiation.
In the theory of classical electromagnetism, accelerating electric charges emit electromagnetic waves. In the most common terrestrial source of X-rays, the X-ray tube, a beam of high-energy electrons impinges on a solid target. As the fast-moving electrons in the beam interact with the electrons and nuclei of the target atoms, they are repeatedly deflected and slowed. During this abrupt deceleration, the beam electrons emit bremsstrahlung (German: “braking radiation”)—a continuous spectrum of electromagnetic radiation with a peak intensity in the X-ray region. Most of the energy radiated in an X-ray tube is contained in this continuous spectrum. Far more powerful (and far larger) sources of a continuum of X-rays are synchrotron particle accelerators and storage rings. In a synchrotron, charged particles (usually electrons or positrons) are accelerated to very high energies (typically billions of electron volts) and then confined to a closed orbit by strong magnets. When the charged particles are deflected by the magnetic fields (and hence accelerated via the change in their direction of motion), they emit so-called synchrotron radiation—a continuum whose intensity and frequency distribution are determined by the strength of the magnetic fields and the energy of the circulating particles. Specially designed synchrotron light sources are used worldwide for X-ray studies of materials.
In an X-ray tube, in addition to the continuous spectrum of radiation emitted by the decelerating electrons, there is also a spectrum of discrete X-ray emission lines that is characteristic of the target material. This “characteristic radiation” results from the excitation of the target atoms by collisions with the fast-moving electrons. Most commonly, a collision first causes a tightly bound inner-shell electron to be ejected from the atom; a loosely bound outer-shell electron then falls into the inner shell to fill the vacancy. In the process, a single photon is emitted by the atom with an energy equal to the difference between the inner-shell and outer-shell vacancy states. This energy difference usually corresponds to photon wavelengths in the X-ray region of the spectrum. Characteristic X-ray radiation can also be produced from a target material when it is exposed to a primary X-ray beam. In this case, the primary X-ray photons initiate the sequence of electron transitions that result in the emission of secondary X-ray photons.
In 1913 the English physicist Henry Moseley discovered a simple relationship between the wavelengths of the X-ray emission lines from a target and the atomic number of the target element—the wavelengths are inversely proportional to the square of the atomic number. Known as Moseley’s law, this relationship proved to be a definitive tool in the determination of atomic numbers in the early days of atomic physics. X-ray fluoresence techniques, in which the wavelengths of characteristic X-rays are recorded following the excitation of a target, are now commonly used to identify the elemental constituents of materials.
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There are three common mechanisms for the production of X-rays: the acceleration of a charged particle, atomic transitions between discrete energy levels, and the radioactive decay of some atomic nuclei. Each mechanism leads to a characteristic spectrum of X-ray radiation.
In the theory of classical electromagnetism, accelerating electric charges emit electromagnetic waves. In the most common terrestrial source of X-rays, the X-ray tube, a beam of high-energy electrons impinges on a solid target. As the fast-moving electrons in the beam interact with the electrons and nuclei of the target atoms, they are repeatedly deflected and slowed. During this abrupt deceleration, the beam electrons emit bremsstrahlung (German: “braking radiation”)—a continuous spectrum of electromagnetic radiation with a peak intensity in the X-ray region. Most of the energy radiated in an X-ray tube is contained in this continuous spectrum. Far more powerful (and far larger) sources of a continuum of X-rays are synchrotron particle accelerators and storage rings. In a synchrotron, charged particles (usually electrons or positrons) are accelerated to very high energies (typically billions of electron volts) and then confined to a closed orbit by strong magnets. When the charged particles are deflected by the magnetic fields (and hence accelerated via the change in their direction of motion), they emit so-called synchrotron radiation—a continuum whose intensity and frequency distribution are determined by the strength of the magnetic fields and the energy of the circulating particles. Specially designed synchrotron light sources are used worldwide for X-ray studies of materials.
In an X-ray tube, in addition to the continuous spectrum of radiation emitted by the decelerating electrons, there is also a spectrum of discrete X-ray emission lines that is characteristic of the target material. This “characteristic radiation” results from the excitation of the target atoms by collisions with the fast-moving electrons. Most commonly, a collision first causes a tightly bound inner-shell electron to be ejected from the atom; a loosely bound outer-shell electron then falls into the inner shell to fill the vacancy. In the process, a single photon is emitted by the atom with an energy equal to the difference between the inner-shell and outer-shell vacancy states. This energy difference usually corresponds to photon wavelengths in the X-ray region of the spectrum. Characteristic X-ray radiation can also be produced from a target material when it is exposed to a primary X-ray beam. In this case, the primary X-ray photons initiate the sequence of electron transitions that result in the emission of secondary X-ray photons.
In 1913 the English physicist Henry Moseley discovered a simple relationship between the wavelengths of the X-ray emission lines from a target and the atomic number of the target element—the wavelengths are inversely proportional to the square of the atomic number. Known as Moseley’s law, this relationship proved to be a definitive tool in the determination of atomic numbers in the early days of atomic physics. X-ray fluoresence techniques, in which the wavelengths of characteristic X-rays are recorded following the excitation of a target, are now commonly used to identify the elemental constituents of materials.
Britannica Quiz
Medical Conditions and Discoveries Quiz
Photographic film was used by Röntgen as one of the first X-ray detectors, and this simple technique remains in wide use in medical applications. The process of exposure is initiated by X-ray photons ionizing radiation-sensitive silver halide crystals in an emulsion on the film surface; the resulting photochemical change of the affected crystals darkens the exposed area (see radiation measurement: Photographic emulsions).
Photographic techniques, while much improved upon since the time of Röntgen and still extremely useful for qualitative applications, are not well-suited for more quantitative measurements of X-ray intensities and spectral content. A number of more effective detection methods have been developed. In a Geiger-Müller tube, or Geiger counter, incoming X-ray photons ionize atoms in a gas-filled volume. An applied high voltage induces further ionizations from collisions between liberated electrons and neutral atoms, creating an avalanche of charged particles and a large electrical pulse that is easily detected. More sophisticated detection schemes based on the ionization of gas atoms can discriminate between X-rays of different energies (see radiation measurement: Proportional counters). Other common detection schemes rely on the ability of X-rays to produce visible fluorescence in crystals (see scintillation counter) and charge separation in semiconductors (see radiation measurement: Semiconductor detectors).
Jul 31, 2023 · X-rays are a form of electromagnetic radiation with wavelengths ranging from 0.01 to 10 nanometers. In the setting of diagnostic radiology, X-rays have long enjoyed use in the imaging of body tissues and aid in the diagnosis of disease. Simply understood, the generation of X-rays occurs when electrons are accelerated under a potential difference and turned into electromagnetic radiation.[1] An ...
- Dawood Tafti, Christopher V. Maani
- 2023/07/31
- 2021
The maximum energy of the produced X-ray photon is limited by the energy of the incident electron, which is equal to the voltage on the tube times the electron charge, so an 80 kV tube cannot create X-rays with an energy greater than 80 keV. When the electrons hit the target, X-rays are created by two different atomic processes:
Oct 31, 2022 · X rays are produced in a more energetic version of the same process. If you want to make X rays, you simply fire a beam of really high-energy electrons (accelerated using a high-voltage electricity supply) at a piece of metal (typically tungsten). What gets reflected back, in this case, is neither light nor electrons but a beam of X rays.
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4 days ago · X-ray, electromagnetic radiation of extremely short wavelength and high frequency, with wavelengths ranging from about 10 −8 to 10 −12 metre and corresponding frequencies from about 10 16 to 10 20 hertz (Hz). X-rays are commonly produced by accelerating (or decelerating) charged particles; examples include a beam of electrons striking a ...
