alpha particle

Also found in: Dictionary, Thesaurus, Acronyms, Encyclopedia, Wikipedia.
Related to alpha particle: Gamma 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
Farlex Partner Medical Dictionary © Farlex 2012

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.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.

alpha particle

a type of subatomic particle found in the atomic nucleus.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005

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.
Medical Dictionary for the Dental Professions © Farlex 2012
References in periodicals archive ?
4 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES, the researchers demonstrate more clearly than before that alpha particles striking and damaging the nuclei of a small fraction of the cells in a population can do enough indirect damage to nearby cells to increase cancer risk almost as much as if all the cells had been hit.
The researchers would isolate the collisions involving electrons within this given energy range, and from these, they would isolate the alpha particles produced in the aftermath.
Assume that neutrons, surrounding an alpha particle before decay of 8He, is polarized the same as in the alpha-particle (1, -2/3, and 1/3).
The upper region above the [sup.3]H cut-off covers the LS response NLS attributed principally to alpha particles and includes the "anomalous bumps" [6] on the low energy shoulder.
Device Rad7 is a system composed of an alpha detector that is located in a Hemisphere chamber, a nuclear electronic system embedded that allow Rad7 to detect the alpha particle. The air contaminated with radon is pumping into the chamber by internal air pump that embedded in the system.
[.sup.210]Po has a relatively short half-life of 138.4 days and decays to lead-206 ([.sup.206]Pb) by emitting an alpha particle. It is the last unstable isotope in the [.sup.238]U decay series and is present in the environment wherever [.sup.238]U or any other members of the [.sup.238]U decay series, such as [.sup.226]Ra, radon, or [.sup.210]Pb, are present.
The XIA UltraLo-1800 is a low background alpha particle counter that employs electronic background suppression to drive achievable background rates to 0.0001 alpha/cm2/hr or lower.
The highest peak on the plot is a result of the XASW interaction with the alpha particles oscillating at the first cyclotron harmonic of helium.
Alpha particles, beta particles and gamma rays emerged as the prime carriers of radioactivity's energy.
Actinium is engaged in the development and commercialization of alpha particle immunotherapeutics based on its unique patent position for the utilization of actinium-225 and bismuth-213.
"It takes a direct hit from just one alpha particle to destroy a lone cancer cell."