An Etymological Dictionary of Astronomy and Astrophysics
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In a compact, steady radio-source where the density of relativistic electrons and the density of synchrotron radiation due to these electrons are very large, the radio photons should be transformed into X-ray and gamma-ray photons through inelastic Compton scatterings onto the relativistic electrons. Thus the radio photons should rapidly disappear and only gamma-ray photons should be observed. This phenomenon does not take place if the radio source is in relativistic expansion.

→ Compton; → catastrophe.

Increase in the wavelength of an → X-ray or → gamma ray  → photon when it collides a → free → electron. The photon transfers part of its energy to the electron, the electron recoils, and the photon itself is scattered at a reduced energy.

→ Compton; → effect.

Theoretical equation which gives the change in the photon wavelength due to the → Compton effect.

→ Compton; → equation.

A period in the early evolution of the Universe, before t = 10^-23 sec when the radius of curvature of the Universe was less than the → Compton wavelength of typical particles.

→ Compton; → era.

The change of direction undergone by the electron in the → Compton effect. The scattered photon and the collided electron move in different directions from that of the incident photon.

→ Compton; → recoil.

Scattering of a → photon due to the → Compton effect.

→ Compton; → scattering.

Of the → Compton effect, the amount of increase in the wavelength of an energetic photon upon its collision with an electron.

→ Compton; → shift.

In → gamma ray → spectroscopy, a technique to reduce the contribution of gamma rays generated by → Compton scattering.

→ Compton; → suppression.

The quantum wavelength of a particle with a highly relativistic velocity. The Compton wavelength is given by h/mc, where h is Planck's constant, m is the mass of the particle, and c the light speed. For an electron, the Compton wavelength is about 2.4 × 10^-10 cm, intermediate between the size of an atomic nucleus and an atom.

→ Compton; → wavelength.

The change in the → spectrum of → electromagnetic radiation due to → scattering from → electrons. When → photons and electrons coexist in the same volume of space, their → collisions can → transfer energy from photons to electrons (→ Compton effect) or from electrons to photons (→ inverse Compton effect).

Verbal noun of → Comptonize; → -tion.

The verb describing the → Camptonization process.

→ Compton; → -ize.

Emission undergone → Comptonization.

→ Comptonize; → emission.

The action or state of forcing or being forced to do something; constraint (OxforddDctionaries.com).

M.E., from O.Fr. compulsion, from L. compulsion-, noun of action from past-participle stem of compellere, → compel.

Verbal noun from vâdâridan, vâdâr kardan, → compel.

The act, process, or method of calculating.

Verbal noun of → compute.

The process or state of computerizing.

→ computerize.

Of a surface, curving inward.

From L. concavus "hollow," from → com- intensive prefix + cavus "hollow;" PIE base *keu- "a swelling, arch, cavity."

Kâv "hollow," verb kâvidan (kâftan) "to dig; to examine, investigate," cf. L. cavus "hollow" (E. derivatives: cavity, concave, cave, excavate), Gk. koilos "hollow," Armenian sor; PIE *kowos "hollow."

A → diffraction grating ruled on a concave spherical mirror that eliminates chromatic aberration and transmits regions of the spectrum, such as the ultraviolet, which is not transmitted by glass lenses.

→ concave; → grating.

A lens which is thinner at the center than at the edges and diverges the light rays.

→ concave; → lens.

A mirror whose surface is curved inward and converges the light rays.

→ concave; → mirror.

A type of → convergent lens that is concave on one surface and convex on the opposite surface. Also called → meniscus lens. Meniscus lenses are used most often in conjunction with another lens to produce an optical system of a longer or shorter → focal length than the original lens.

→ concave; → convex; → lens.