alpha particle

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alpha particle,

one of the three types of radiation resulting from natural radioactivityradioactivity,
spontaneous disintegration or decay of the nucleus of an atom by emission of particles, usually accompanied by electromagnetic radiation. The energy produced by radioactivity has important military and industrial applications.
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. Alpha radiation (or alpha rays) was distinguished and named by E. R. Rutherford in 1909, who found by measuring the charge and mass of alpha particles that they are the nuclei of ordinary helium atoms. Alpha particles consist of two protons and two neutrons (see nucleusnucleus,
in physics, the extremely dense central core of an atom. The Nature of the Nucleus
Composition

Atomic nuclei are composed of two types of particles, protons and neutrons, which are collectively known as nucleons.
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).

alpha particle

(α particle) The nucleus of a helium atom, i.e. a positively charged particle consisting of two protons and two neutrons. It is thus a fully ionized helium atom. Alpha particles are very stable. They are often ejected in nuclear reactions, including alpha decay in which a parent nucleus disintegrates – or breaks up – into an alpha particle and a lighter daughter nucleus.

alpha particle

[′al·fə ‚pärd·ə·kəl]
(atomic physics)
A positively charged particle consisting of two protons and two neutrons, identical with the nucleus of the helium atom; emitted by several radioactive substances.

alpha particle

a helium-4 nucleus, containing two neutrons and two protons, emitted during some radioactive transformations

alpha particle

References in periodicals archive ?
This means that in the first case, with the excess of protons, addition of a neutron leads to the formation of an entire cluster (alpha-particles) and in the second case, with the excess of neutrons,--to another quark be only involved in a common bound nucleus structure.
Suppose that the distance [r.sub.i] between the vortex tubes cannot be less than the size of alpha-particles (4 Fermi).
As a result of this project, we were able to confirm the conclusion that histogram shapes depend on the diurnal rotation of the Earth, and to show that, when alpha-particle beam is directed along the meridian, the histogram shape changes synchronously from the North Pole to the Antarctic.
This paper is based on the results obtained from the simultaneous measurements of alpha-activity of the [sup.239]Pu samples with the activity of 100-300 registered decay events per second using 9 different devices with semiconductor alpha-particle detectors constructed by one of the authors (I.
Figure 10 was the alpha-particle energy spectra acquired for 30 s and 180 s and total counts were 15,834 counts and 50,969 counts for 30 s and 180 s, respectively.
In the present study, the Sb[I.sub.3] detector was continuously operated at room temperature and alpha-particle energy spectra were recorded as a function of time to evaluate the polarization phenomenon in the detector.