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 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 ?
The high linear energy transfer of alpha emitters leads to a high frequency of double-strand DNA breaks in adjacent tumor cells, resulting in a potent cytotoxic effect.
We do not dispute Nussbaum's argument that additional doses may have been received from alpha emitters incorporated internally and that these might have been more than is acknowledged by UNSCEAR and the World Health Organization (WHO).
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The analyzes are performed radiological analysis, mainly measuring alpha emitters, and gamma spectrometry, alpha counts, beta whose research Sr90, measuring the tritium and C14 by liquid scintillation.
The Priorities apply to practical radiation protection: such as workplace monitoring, performance of clearance measurements in accor dance with paragraph 29 of the Radiation Protection Regulation (StrlSchV) for alpha emitters, knowledge of safety issues When handling radioactive substances in Gloveboxes and hot cells, and emergency Precautions in the event of contamination.