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 ?
Given the above, referring to the adopted charges layout, the alpha particles geometry, and specified dimensions, one can write the final formula for the binding energy as the average energy per bond at subtracting the repulsive potentials of protons as whole units and the fractional charge repulsion potentials of neutrons:
this is done by special filters for absorbing radon inside the counter machine and the alpha particles emitted from it are counted by ionization chamber in counter machine.
210]Po accumulates in reproductive and embryonic and fetal tissues where a single alpha particle can kill or damage critical cells.
During the planning stages, the radiation dose rates to tissue within range of the alpha particles emitted by either the uranium- or thorium-series isotopes were estimated as follows.
If the Hoyle state energy was at 479 keV or more above the three alpha particles, then the amount of carbon produced would be too low for carbon-based life," Lee said.
The proton hit the boron nucleus and produced two high energy alpha particles and one that was slower.
Sigmar made important contributions to the understanding of collisional transport in tokamaks and the behavior of alpha particles in fusing plasmas, and played a leadership role in the development of an edge and divertor physics program in the U.
1 [micro]Ci, Spectrum Industries, Oak Ridge, TN), as measured in an alpha particle spectrometer (Alpha-King Spectrometer, EG&G Ortec, Oak Ridge, TN), was used to measure peak smearing and energy shift dependence upon lead thickness in both slices and vacuum-deposited thin films of lead.
We are seeing a growing concern about alpha particle effects.
The alpha particle beta and energetic particle heating effects in these experiments were reactor-like, allowing the first exploration of BP physics.
The testing of multiple variants of a chip design has been conducted at the Los Alamos Neutron Sciences Center (LANSCE) at Los Alamos National Laboratory in New Mexico utilizing the fast neutron beam line, and at iRoC Technologies laboratory in Grenoble, France for the Alpha particle campaign.
When actinium decays, it produces a series of daughter atoms, each of which gives off its own alpha particle, increasing the chances that the cancer cell will be destroyed.