scattering

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scattering

1. the random deflections suffered by light or other electromagnetic radiation passing through an irregular medium. If the source, medium, or observer are in relative motion, scintillations – random fluctuations of amplitude – may be seen as the source is observed through the medium: scattering in the Earth's atmosphere causes the stars to twinkle. Scintillations may only be seen if both the angular size of the source and the bandwidth in which the waves are received are small enough. Otherwise, the effect of the scattering may simply be to broaden the apparent angular size of the source.

Scintillations of radio waves are observed to occur because of irregularities in the refractive index of the ionosphere, the interplanetary medium, and the interstellar medium giving ionospheric scintillation, interplanetary scintillation (IPS), and interstellar scintillation (ISS), respectively. IPS may be used in determining the angular sizes of radio sources at meter wavelengths in the range 0.1 to 2 arc seconds, or for measuring parameters of the solar wind. ISS cause some of the random fluctuations in the intensity of pulses received from pulsars.

Light may be deflected from its direction of travel by fine particles of solid, gaseous, or liquid matter. For very small particles (less than one wavelength in size) the effect results from diffraction, reflection playing a more important part with increasing size; this is known as Rayleigh scattering and is very dependent on wavelength. Very small particles scatter blue light more strongly than red light. This leads to the reddening of starlight by cosmic dust and to the reddening of the Sun when seen through a thick layer of atmospheric dust.

2. the deflection of individual particles (such as electrons or photons) from their direction of travel as a result of their interaction with other particles, nuclei, atoms, or molecules in the medium through which they are passing. There are various scattering processes including Compton scattering.

scattering

[′skad·ə·riŋ]
(electromagnetism)
Diffusion of electromagnetic waves in a random manner by air masses in the upper atmosphere, permitting long-range reception, as in scatter propagation. Also known as radio scattering.
(physics)
The change in direction of a particle or photon because of a collision with another particle or a system.
Diffusion of acoustic or electromagnetic waves caused by inhomogeneity or anisotropy of the transmitting medium.
In general, causing a collection of entities to assume a less orderly arrangement.
References in periodicals archive ?
Due to the slot-scanning technology, there is less scattered radiation and imaging of the vertebral column is improved.
However, bias error arises in the case of diffuse transmission measurements because the scattered radiation originating at the sample is not distributed uniformly over the surface of the integrating sphere and the radiation sensed by the detectors includes the first reflection of this non-uniform distribution.
Helmrot E, Carlsson GA, Eckerdal O, Sandborg M: Influence of scattered radiation and tube potential on radiographic contrast: Comparison of two dental x-ray films.
However, DBT shows high levels of scattered radiation within the image receptor which can reduce significantly the visibility of breast lesions and the lesion detection performance of computer-aided diagnosis (CAD) systems.
In order to prevent the untoward effects of radiation, shielding of the remaining testis in a proper manner is crucial to avoid the harmful effects of the scattered radiation.
Collimation cuts down on radiation to all body parts and improves film quality by reducing scattered radiation.
2] as the apparent absorbance obtained with the sample placed nearer to the detector, the intensity of scattered radiation is related to the difference between these values, as analyzed in a previous study (24) by considering the apparent geometry, of the equation:
By observing any scattered radiation, they could detect the presence of a liquid lead layer on the surface of a single crystal of lead.
SenoScan's small pixel size and patented slot scanning detector provide for a detective quantum efficiency (DQE) that exceeds the performance of any other FDA-approved digital mammography system available, and the system's exclusive detector and x-ray tube combination allows for a narrowly collimated x-ray beam that reduces the amount of scattered radiation.
Proton therapy is situated within the field of medicine irradiation, but it is characterized by a focused energy release of the proton particles which makes it possible to irradiate quite focused on the tumor itself and a lower scattered radiation.
The X-Drape[R], which is provided sterilized and ready to use, is a disposable product that provides protection from scattered radiation associated with X-ray Fluoroscopy.