alpha particle


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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 particle emitted from an atom during one kind of radioactive decay. It consists of two protons and two neutrons, the equivalent of a helium nucleus. Ordinarily, alpha particles are a weak form of radiation with a short range and are not considered hazardous unless inhaled or ingested.

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.
References in periodicals archive ?
210]Po through the digestive tract may increase sharply (Moroz and Parfenov 1972), possibly because of damage to the intestinal wall through persistent bombardment by alpha particles.
One can also maintain that the tower world may be indeterministic - this will hinge on what happens at more populated tower collapse worlds, but one can nevertheless reject the claim of indeterminism for either kind of alpha particle decay.
35,36] However, a continuing alpha particle bombardment from [sup.
0 MeV, which corresponds well to the actual alpha particles binding energy (28.
That is, as the radiation source becomes more distributed--by deformation, by fragmentation, or by dispersion amid the soft tissue--the number of cells within range of the alpha particles increases.
Carbon-12, an essential element we're all made of, can only form when three alpha particles, or helium-4 nuclei, combine in a very specific way.
Weller and the team at the Triangle Universities Nuclear Laboratory expected that when hydrogen and boron fused, the result would be a three alpha particles, or helium nuclei.
As a result of his pioneering work on alpha particle theory, he served on the Tokamak Fusion Test Reactor Deuterium-Tritium Program Advisory Committee and was a co-organizer of an international alpha particle workshop.
This introduced radioactive isotopes into the flux during processing so that the resulting lead contained polonium isotopes as determined by alpha particle counting.
Alpha Sciences provides equipments for sale and training focused on the alpha particle detection and measurement of all components of the semiconductor device.
Actinium's License, Development and Commercialization Agreement (License Agreement) with MSK, which already included issued patents pertaining to the company's Alpha Particle Immunotherapy (APIT) technology platform and drug preparation methods now includes these recently allocated provisional patent applications.
The Alpha Particle X-ray Spectrometer and the Mars Hand Lens Imager, which share the turret with the brush and the rover's hammering drill, can gain data after dust removal, which usually would not be accessible from a dust-blanketed rock.