alpha particle

n. A positively charged subatomic particle, composed of two protons and two neutrons, identical with the nucleus of the helium isotope He-4.

alpha particle

n (General Physics) a helium-4 nucleus, containing two neutrons and two protons, emitted during some radioactive transformations

al′pha par`ticle

n. a positively charged particle consisting of two protons and two neutrons, emitted in radioactive decay or nuclear fission; the nucleus of a helium atom. [1900–05]

alpha particle

A positively charged particle that consists of two protons and two neutrons bound together. It is emitted by the nucleus of some elements undergoing radioactive decay and is identical to the nucleus of a helium atom. Alpha particles are the slowest and least penetrating forms of nuclear radiation. ♦ The process by which a radioactive element emits an alpha particle is called alpha decay. Alpha decay results in the atomic number of the atom being decreased by two and the mass number being decreased by four. See more at radiation, radioactive decay.

alpha particle

A helium nucleus that has a positive electric charge.

Thesaurus

Noun

alpha particle - a positively charged particle that is the nucleus of the helium atom; emitted from natural or radioactive isotopessubatomic particle, particle - a body having finite mass and internal structure but negligible dimensions

alpha particle

al·pha par·ti·cle (α),

a particle consisting of two neutrons and two protons, with a positive charge (2e⁺); emitted energetically from the nuclei of unstable isotopes of high atomic number (elements of mass number from 82 up); identical to the helium nucleus. Synonym(s): alpha ray

alpha particle

A radioactive decay product, 4He nucleus, composed of two protons and two neutrons (the same as the nucleus of a helium-4 atom) with marked ionising capacity (3–9 million electron-volts) but a short range (3–9 cm in air, 25–40 µm in water/soft tissue), derived from alpha decay, which are created by the decay of a radioactive material or from nuclear bombardment. APs arising from radon, uranium and plutonium “daughters” are implicated in inhalation-induced neoplasia of the respiratory tract.
While alpha particles are highly tissue-destructive, they travel only short distances and are blocked by a thick piece of paper or skin; an AP is essentially a helium atom nucleus and generally carries more energy than gamma or beta radiation, depositing that energy very quickly while passing through tissue. Alpha particles cannot penetrate the outer, dead layer of skin; they therefore do not cause damage to living tissue when outside the body. When inhaled or ingested, however, APs are especially damaging because they transfer relatively large amounts of ionising energy to living cells.

alpha particle

a type of subatomic particle found in the atomic nucleus.

al·pha par·ti·cle

(alfă pahrti-kĕl) A particle consisting of two neutrons and two protons, with a positive charge; emitted energetically from the nuclei of unstable isotopes of mass number 82 and up.
Synonym(s): alpha ray.

alpha particle

alpha particle

alpha particle

al′pha par`ticle

alpha particle

alpha particle

alpha particle

al·pha par·ti·cle (α),

alpha particle

alpha particle

al·pha par·ti·cle

alpha particle

Words related to alpha particle

noun a positively charged particle that is the nucleus of the helium atom

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