collisional cross section
sekanj-e oskarmand-e hamkubeši
Fr.: section efficace de collision
Same as → cross section.
Fr.: section conique
Fr.: 1) section plane; 2) section efficace
1) Math: The intersection of a plane with a geometric figure,
usually at right angles to an axis of symmetry.
In classical mechanics, the cross section for the collision of a point particle with a hard sphere is just be the surface of a section through the middle of the sphere. This explains the name "cross section." → cross; → section.
The act of dissecting.
The act, process, or result of intersecting.
Verbal noun of → intersect.
minimum orbit intersection distance (MOID)
durâ-ye kamine-ye andarsekanj-e madâr
Fr.: distance minimale d'intersection d'une orbite
The minimum distance between the paths of two orbiting objects around a → primary. Such distance between an object and Earth is called Earth MOID.
Fr.: section efficace nucléaire
Apparent cross-section possessed by an atomic nucleus when it undergoes a particular type of collision process.
From M.Fr. section, from L. sectionem "a cutting, division," from secare "to cut;" PIE base *sek- "cut" (cf. O.C.S. seko, sesti "to cut," Lith. isekti "to engrave, carve;" O.S. segasna, O.E. sigðe "scythe;" O.E. secg "sword," seax "knife, short sword").
Sekanj "a scraping, shaving, cutting," cognate with Pers. šekast-, šekastan "to break;" Av. skand- "to break," Skt. khand- "to break," khanda- "piece;" Pers. dialect Tabari šag "a special razor used to make incisions in the walls of unripe opium poppies in order to extract the milky sap," may be related to PIE *sek- "cut," as above.
Thomson cross section
Fr.: section efficace de Thomson
The → cross section involved the → Thomson scattering of electromagnetic waves by a free electron. It is defined by: σT = 8πre2/3, where re is the classical → electron radius. Its value is 0.665 245 x 10-28 m2.