An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

   Homepage   
   


A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

<< < -ab aba abs abs abs acc acc act act ada adi adv aff age Alc Alf ali all alp alt amb an- ana Ang ang ann Ant ant ant apo app app Ara Arc Ari art ass ast ast ast atm ato att aut awa azi > >>

Number of Results: 902
atomic fountain clock
  ساعت ِ فواره‌ی ِ اتمی   
sâ'at-e favvâre-ye atomi

Fr.: horloge à fontaine atomique   

An → atomic clock based on the principle of the → atomic fountain. A ball of atoms, usually → cesium (133Cs), created by the → laser cooling technique, is trapped in the intersection region of six laser beams. The ball is thrown upward by a laser beam and passes twice through a cavity where the atoms interact with the → microwave radiation generated by an → oscillator. The ball reaches the summit of its trajectory (about 1 m above the cooling zone) and then due to gravity falls through the same microwave cavity. The microwave radiation causes the electrons of the cesium atoms to move between two specific → energy states as they pass through the cavity. The clock is based on a → hyperfine transition (9.192631770 GHz) between two energy states in the electronic → ground state of the atom. The upper hyperfine state can in principle radiate to the lower state by → spontaneous emission, but the process takes a very long time -- thousands of years. Selection and detection of the hyperfine state is performed via → optical pumping and laser induced resonance fluorescence. In a carefully controlled setup, a relative uncertainty of 10 -16 can be reached for the cesium clock. This means an accuracy of 1 sec every 300 million years. This fluorescence is measured by a detector. The entire process is repeated until the maximum fluorescence of the cesium atoms is determined. This determination is used to lock the oscillator to the atomic frequency of cesium, which is used to define the SI → second. The first atomic fountain for metrological use was developed at the Paris Observatory (A. Clairon et al. 1996, Proc. 5th Symp. Frequency Standards and Metrology, p. 45).

atomic fountain; → clock.

atomic heat
  گرمای ِ اتمی   
garmâ-ye atomi

Fr.: chaleur atomique   

The → heat capacity of a → mole of a substance, expresses as: Ca = C.A , where C is the → specific heat and A the → atomic weight .

atomic; → heat.

atomic hydrogen
  هیدروژن ِ اتمی   
hidrožen-e atomi (#)

Fr.: hydrogène atomique   

Same as → neutral hydrogen or → H I.

atomic; → hydrogen.

atomic mass number (A-number)
  عدد ِ جرم ِ اتمی   
adad-e jerm-e atomi (#)

Fr.: nombre de masse atomique   

The total number of → protons and → neutrons in the → nucleus of an → atom (symbol A). For example, Oxygen-16 has a mass number of sixteen, because it has eight protons and eight neutrons.

atomic; → mass; → number.

atomic mass unit (amu)
  یکای ِ جرم ِ اتمی   
yekâ-ye jerm-e atomi (#)

Fr.: unité de masse atomique   

A unit of mass used for atoms and molecules, equal to 1/12 of the mass of an atom of carbon-12 (including orbital electrons). It is equal to 1.660 33 × 10-24 g.

atomic; → mass; → unit.

atomic nucleus
  هسته‌ی ِ اتم   
haste-ye atom (#)

Fr.: noyau atomique   

The central part of the → atom. It is made up of → protons and, in most cases, → neutrons. The nucleus is surrounded by a swarm of fast-moving → electrons. Almost all of the mass (more than 99%) of an atom is contained in the dense nucleus. The number of protons in the nucleus (called → atomic number) determines the type of → chemical element. Atoms that differ only in the number of neutrons in their nuclei are called → isotopes.

atomic; → nucleus.

atomic number
  عدد ِ اتمی   
adad-e atomi (#)

Fr.: nombre atomique   

The number of → protons in an → atomic nucleus (symbol Z). Same as → Z-number. The atomic number is written as a subscript to the left of the → chemical element name. For example, the most common isotope of oxygen is shown as 816O, which has 8 → protons and its → mass number (A) is 16.

atomic; → number.

atomic proposition
  گزاره‌ی ِ اتمی   
gozâre-ye atomi

Fr.: proposition atomique   

In → propositional logic, a → sentence without any → connectives. See also → molecular proposition.

atomic; → proposition.

atomic time
  زمان ِ اتمی   
zamân-e atomi (#)

Fr.: temps atomique   

Time measured using atomic clocks.

atomic; → number.

atomic transition
  گذرش ِ اتمی   
gozareš-e atomi

Fr.: transition atomique   

A change in the → energy level or → state of an → atom in which a → quantum of energy is either gained or lost. See also → forbidden transition; → permitted transition; → semiforbidden transition.

atomic; → transition.

atomic weight
  وزن ِ اتمی   
vazn-e atomi (#)

Fr.: poids atomique   

The mean atomic mass of a particular → chemical element in → atomic mass unit.

atomic; → weight.

atomic wff
   wff اتمی   
wff atomi

Fr.: FBF atomique   

i) If t1, t2, ..., tn are terms and P is a → predicate of arity n, then P(t1, t2, ..., tn) is an atomic wff.
ii) If t1 and t2 are terms, then (t1 = t2) is an atomic wff.

atomic; → wff.

attend
  آتانیدن   
âtânidan

Fr.: attendre   

To pay attention.

M.E. atenden, from O.Fr. atendre "to expect, wait for, pay attention," from L. attendere "give heed to," literally "to stretch toward," from → ad- "to" + tendere "stretch," → tension.

Âtânidan, from prefix â- + tân, from tan-, tanidan "to spin, twist, weave" (cf. tân "thread, warp of a web," variants târ "thread, warp, string," tâl "thread" (Borujerdi dialect), tur "fishing net, net, snare"); Mid.Pers. tanitan; Av. tan- to stretch, extend;" cf. Skt. tan- to stretch, extend;" tanoti "stretches," tantram "loom;" tántra- "warp; essence, main point;" Gk. teinein "to stretch, pull tight;" L. tendere "to stretch;" Lith. tiñklas "net, fishing net, snare;" PIE base *ten- "to stretch."

attention
  آتانش   
âtâneš

Fr.: attention   

1) The act or faculty of attending, especially by directing the mind to an object.
2) Observant care; consideration (Dictionary.com).

attend; → -tion.

attentive
  آتانمند   
âtânmand

Fr.: attentif   

1) Characterized by or giving attention; observant.
2) Thoughtful of others; considerate; polite; courteous (Dictionary.com).

attend; → -ive.

attenuate
  تنکیدن   
tonokidan (#)

Fr.: atténuer   

1) To reduce in force, value, amount, or degree. → attenuation, → attenuation factor.
2) To reduce the amplitude of an electrical signal with little or no distortion.

L. attenuatus, p.p. of attenuare "to make thin," from → ad- "to" + tenuare "make thin," from tenuis "thin;" cf. Gk. tanaos "thin, slender, elongated;" Skt. tanuka-, tanu- "thin;" Av. tan- "to stretch;" Pers. tonok "thin," as below; O.Ir. tanae "delicate, thin;" O.H.G. dunni "thin."

Tonokidan, from tonok "thin, slender, slight, tender, delicate" + -idan, infinitive suffix. Tonok, from Mid.Pers. tanuk, Av. root tan- "to stretch, extend," cognate with L. tenuis, as above.

attenuation
  تنکش   
tonokeš (#)

Fr.: atténuation   

The falling off of the energy density of radiation with distance from the source, or with passage through an absorbing or scattering medium.

Verbal noun of → attenuate.

attenuation coefficient
  همگر ِ تنکش   
hamgar-e tonokeš

Fr.: coefficient d'bsorption   

The fraction of a beam of → X-rays or → gamma rays that is absorbed or scattered per unit thickness of the → absorber. The linear attenuation coefficient, denoted by the symbol μ, appears in the equation I(x) = I0ex, where I(x) is the intensity at depth of x cm and I0 is the original intensity.

attenuation; → coefficient.

attenuation factor
  کروند ِ تنکش   
karvand-e tonokeš

Fr.: facteur d'atténuation   

The ratio of the radiation intensity after traversing a layer of matter to its intensity before.

attenuation; → factor.

attitude
  رویکرد   
ruykard (#)

Fr.: attitude   

Position of a satellite with respect to the horizon or some other fixed reference plane.

Fr., from It. attitudine "disposition, posture," from L.L. aptitudo "faculty."

Ruykard, noun from ruy kardan "to turn the face toward," from ruy "face" (Mid.Pers. rôy, rôdh "face," Av. raoδa- "growth," in plural "appearance," from raod- "to grow, sprout, shoot," cf. Skt. róha- "rising, height") + kardan "to do, make, perform" (Mid.Pers. kardan, O.Pers./Av. kar- "to do, make, build," Av. kərənaoiti "makes," cf. Skt. kr- "to do, to make," krnoti "makes," karma "act, deed;" PIE base kwer- "to do, to make").

position.

<< < -ab aba abs abs abs acc acc act act ada adi adv aff age Alc Alf ali all alp alt amb an- ana Ang ang ann Ant ant ant apo app app Ara Arc Ari art ass ast ast ast atm ato att aut awa azi > >>