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A Collection of Radioactive Decay Terms...
α
A symbol for alpha particle.

α decay
A synonym for alpha decay.

α particle
A synonym for alpha particle.

actinium decay series
The nuclides fed in the radioactive decay of 235U including all daughters through stable 207Pb. Also known as the (4n+3) series because each member of the series has a mass equivalent to (4n+3), where n is an integer.

Synonym: actinium series.
Related to thorium decay series.
Related to uranium decay series.


actinium series
A synonym for actinium decay series.

activation
Of or pertaining to the process of inducing radioactivity by bombarding a nuclide with radiation.

alpha
A synonym for alpha particle.

alpha particle
A 4He nucleus, a helium isotope that contains two protons and two neutrons. The term alpha is reserved for 4He nuclei emitted during radioactive decay or as an ejectile in a nuclear reaction. The name alpha was coined by Rutherford in 1897.

Reference: E. Rutherford. Phil. Mag. 7, 109 (1897).
Symbol: α.
Symbol: 4He2+.
Synonym: α particle.
Synonym: alpha.
Synonym: alpha radiation.
Synonym: alpha ray.
Related to alpha decay.
Related to beta particle.
Related to gamma ray.
Related to positron.


alpha decay
Radioactive disintegration by emission of an alpha particle.

Synonym: α decay
Synonym: alpha change
Synonym: alpha disintegration
Synonym: alpha emission
Synonym: alpha particle decay
Synonym: alpha transformation
Synonym: alpha transition
Related to alpha particle.
Related to beta decay.
Related to electron capture decay.
Related to spontaneous fission.


alpha particle decay
A synonym for alpha decay.

atom disintegration
A synonym for radioactive decay.

atomic disintegration
A synonym for radioactive decay.

β
A symbol for beta particle.

β-
A symbol for beta particle.

β+
A symbol for positron.

β- decay
Decay by emission of a β- particle.

Synonym: beta decay
Synonym: negatron decay
Related to β- particle.
Related to positron decay.


β- particle
The electron emitted by a nucleus during beta decay.

Synonym: decay electron
Synonym: disintegration electron
Related to alpha particle.
Related to beta decay.
Related to beta particle.
Related to gamma ray.
Related to positron.


beta
A synonym for beta particle.

beta decay
Decay by emission of a beta particle. Three types of beta decay are common in nuclei: Neutron rich nuclei tend to decay by emitting a β- particle. An antineutrino is also emitted in this type of b decay and the it results in the nucleus converting a neutron into a proton. Neutron deficient nuclei tend to decay by positron emission or electron capture. Positron emission refers to the emission of a positron (β+), which is the antiparticle of the electron. A neutrino is emitted in the process and this results in the nucleus converting a proton into a neutron. Electron capture is usually classified as a type of beta decay and involves an orbital electron being absorbed by a nucleus, effectively converting a proton into a neutron.

Synonym: β decay
Synonym: beta change
Synonym: beta disintegration
Synonym: beta emission
Synonym: beta particle decay
Synonym: beta transformation
Related to alpha decay.
Related to β- decay.
Related to beta particle.
Related to double beta decay.
Related to dual beta decay.
Related to positron decay.
Related to spontaneous fission.


beta-delayed neutron
A neutron that has been emitted by an excited state of a nucleus immediately following beta decay. The emission occurs when the decay leaves the daughter nucleus in an excited state that is above the neutron separation energy. Delayed neutrons account for approximately 0.75% of the neutron output from fission and this is an important aspect of controlling the increase in energy output of reactors.

Related to delayed fission neutron.
Related to fission neutron.
Related to prompt fission neutron.


beta particle
The electron or positron (the antiparticle of the electron) emitted by a nucleus during beta decay. The name beta was coined by Rutherford in 1897.

Reference: E. Rutherford. Phil. Mag. 47, 109 (1897).
Symbol: β.
Symbol: β-.
Symbol: β+.
Synonym: beta.
Synonym: beta radiation.
Synonym: beta ray.
Synonym: decay electron.
Synonym: disintegration electron.
Related to alpha particle.
Related to beta decay.
Related to gamma ray.
Related to positron.


beta radiation
A synonym for beta particle.

beta ray
A synonym for beta particle.

conversion
Of or pertaining to internal conversion.

daughter
A synonym for daughter nuclide.

daughter element
A synonym for daughter nuclide.

daughter nuclide
The nuclide produced in radioactive decay.

Synonym: daughter.
Synonym: daughter element.
Synonym: decay product.
Synonym: descendent.
Related to decay chain.
Related to parent nuclide.


daughter product
A synonym for daughter nuclide.

decay
A synonym for radioactive decay.

decay chain
A series of nuclides linked in a chain by radioactive decay. Each nuclide in the chain decays to the next until a stable nuclide is reached.

Synonym: decay family.
Synonym: decay series.
Synonym: disintegration chain.
Synonym: disintegration family.
Synonym: disintegration series.
Synonym: family.
Synonym: radioactive decay chain.
Synonym: radioactive family.
Synonym: radioactive series.
Related to daughter nuclide.
Related to parentage.
Related to parent nuclide.


decay daughter
A synonym for daughter nuclide.

decay electron
A synonym for beta particle.

decay energy
A synonym for decay Q-value.

decay family
A synonym for decay chain.

decay heat
Heat produced through radioactive decay. It is especially important for fission products.

Acronym: DH.
Related to after heat.


decay mode
A particular type of radioactive decay. Examples include β- decay, β+ decay, a decay, internal transition, and spontaneous fission.

decay product
A synonym for daughter nuclide.

decay Q-value
The total energy that can be emitted in radioactive decay.

Synonym: decay energy.
Synonym: disintegration energy.
Synonym: nuclear disintegration energy.
Related to Q-value.


decay rate
A synonym for activity.

decay scheme
A level scheme populated in radioactive decay.

Related to level scheme.

decay series
A synonym for decay chain.

delayed fission neutron
A neutron emitted by a fission product.

Related to beta-delayed neutron.
Related to fission neutron.
Related to prompt fission neutron.


delayed neutron
Acronym: DN.
See instead beta-delayed neutron.


descendent
A synonym for daughter nuclide.

disintegration
A synonym for radioactive decay.

disintegration chain
A synonym for decay chain.

disintegration constant
A synonym for decay constant.

disintegration electron
A synonym for beta particle.

disintegration energy
A synonym for decay Q-value.

disintegration family
A synonym for decay chain.

disintegration rate
A synonym for activity.

disintegration series
A synonym for decay chain.

double beta decay
Radioactive decay that occurs with the emission of two β- particles. It is a rare type of decay.

Synonym: ββ decay.
Synonym: β-β- decay.
Synonym: double-beta disintegration.


dual beta decay
For a nuclide it is a term that refers to the existence of beta minus and positron emission decay modes.

Related to beta decay.
Related to β- decay.
Related to positron decay.


e+
A symbol for positron.

e-
A symbol for electron.

electron capture
A synonym for electron capture decay.

electron capture decay
Radioactive disintegration by capture of an atomic electron. Electron capture belongs to the general category of beta decay.

Symbol: e-c.
Synonym: electron capture.
Related to alpha decay.
Related to beta decay.
Related to spontaneous fission.


family
A synonym for decay chain.

γ ray
A synonym for gamma ray.

gamma ray
Electromagnetic radiation emitted by a nucleus with a very short wavelength. These radiations result from the de-excitation of an excited state in a nucleus. Individual gamma-ray quanta are also known as photons. Gamma rays were first observed by Villard in 1900.

Reference: P. Villard. CR Acad. Sci. (Paris) 130, 1010, 1178 (1900).
Symbol: γ.
Synonym: γ ray.
Synonym: gamma photon.
Synonym: gamma radiation.
Synonym: gamma-ray photon.
Related to alpha particle.
Related to beta particle.
Related to electromagnetic radiation.
Related to x-rays.


negatron
(obsolete term)

A synonym for beta particle.

nuclear disintegration
A synonym for radioactive decay.

nuclear disintegration energy
A synonym for decay Q-value.

nuclear energy
Energy released by radioactive decay, through a nuclear reaction, or in the course of nuclear fission.

A synonym for nuclear power.
Synonym: atomic energy.
Synonym: (obsolete) tomic energy.


o-Ps
A symbol for ortho positronium.

ortho positronium
An atom-like system composed of a positron and an electron whose spins are parallel, in a triplet state. The mean life of ortho positronium is 10-7 s.

Symbol: o-Ps.
Related to para positronium.
Related to positron.
Related to positronium.
Related to triplet state.


para positronium
An atom-like system composed of a positron and an electron whose spins are antiparallel, in a singlet state. The mean life of para positronium is 10-10 s.

Symbol: p-Ps.
Related to ortho positronium.
Related to positronium.


parent
A synonym for parent nuclide.

parentage
The relationship of a nuclide to a second nuclide through a single radioactive decay. The initial nuclide is known as the parent and the product nuclide is known as the daughter.

Related to daughter nuclide.
Related to decay chain.
Related to parent nuclide.


parent nuclide
The first of two nuclides linked by radioactive decay. A parent decays to a daughter nuclide.

Synonym: parent.
Related to daughter nuclide.
Related to decay chain.


positon
An early proposed name for the positron. It was proposed by the Cosmic Ray Commission of the International Union of Physics at their annual meeting in October 1947.

A synonym for positron.

positron
The antiparticle of the electron. Its mass and spin are identical to that of the electron but it has a charge of +1.

Symbol: e+.
Symbol: β+.
Synonym: positive electron.
Synonym: positon.
Related to beta particle.
Related to electron.
Related to exotic atom.


positron decay
Disintegration by emission of a positron. A neutrino is also emitted in this type of decay and the decay results in the nucleus converting a proton into a neutron.

Synonym: β+ decay
Synonym: positron emission
Related to β- decay.
Related to beta decay.
Related to positron.


positronium
An atom-like system formed between an electron and a positron. One of the two particles acts as a nucleus with the other particle orbiting around it. The positronium is unstable and annihilates forming two photons each with an energy of 511 keV, the rest mass of the electron.

Related to ortho positronium.
Related to para positronium.


p-Ps
A symbol for para positronium.

Q-value
The energy released in a nuclear reaction or in radioactive decay as calculated from the difference in total energy (including rest mass) of the products (product nuclei and ejectiles) and reactants (target nuclei and projectiles). When applied to radioactive decay, the target nucleus is the parent nuclide, the daughter nucleus is the product nuclide, and there is no projectile.

Symbol: Q.
Synonym: reaction energy


radioactive
Having the capacity to undergo spontaneous disintegration by the emission of radiation. The term applies to an atom, a collection of atoms or an object.

radioactive decay
Spontaneous emission by a nucleus of photons or particles.

The spontaneous transformation of one nuclide into another by emission of particles, absorption of an orbital electron, or by fission. It also refers to gamma-ray and conversion electron emission that only reduces the excitation energy of the nucleus.

Synonym: atom disintegration.
Synonym: atomic disintegration.
Synonym: decay.
Synonym: disintegration.
Synonym: nuclear disintegration.
Synonym: radioactive disintegration.


radioactive decay chain
A synonym for decay chain.

radioactive disintegration
A synonym for radioactive decay.

radioactive family
A synonym for decay chain.

radioactive material
(1) (49CFR173.403y) Material with a specific activity of greater than 0.002 mCi/g.

(2) (10CFR76) Source material, special nuclear material, or byproduct material, possessed, used, transferred, or disposed of.

Acronym: RAM.

radioactive isotope
A nuclide that is radioactive.

radioactive nuclide
An nuclide capable of undergoing radioactive decay.

Synonym: stable nuclide.
Synonym: (colloquial) unstable isotope.


radioactive series
A synonym for decay chain.

radioactivity
Of or pertaining to radioactive nuclides, or objects or matter containing radioactive nuclides.

radioisotope
A synonym for radionuclide.

radionuclide
A radioactive nuclide.

Synonym: radioisotope.

singlet state annihilation
Annihilation of a singlet positronium, an atom-like structure in which the positron and electron spins are antiparallel. This form of annihilation produces two photons.

Synonym: two photon annihilation
Related to para positronium.
Related to triplet state annihilation.


spontaneous fission
Fission that occurs spontaneously, not induced by an incident particle. A type of radioactive decay.

Related to fission.
Related to fission fragment.
Related to fission neutron.
Related to fission product.
Related to photofission.
Related to ternary fission.


thorium decay series
The nuclides fed in the radioactive decay of 232Th including all daughters through stable 208Pb. Also known as the (4n) series because each member of the series has a mass equivalent to (4n), where n is an integer.

Synonym: thorium series.
Related to actinium decay series.
Related to uranium decay series.


thorium series
A synonym for thorium decay series.

triplet state annihilation
Annihilation of a triplet positronium, an atom-like structure in which the positron and electron spin s are parallel. This form of annihilation produces three photons.

Synonym: three photon annihilation
Related to ortho positronium.
Related to singlet state annihilation.


two photon annihilation
A synonym for singlet state annihilation.

uranium decay series
The nuclides fed in the radioactive decay of 238U including all daughters through stable 206Pb. Also known as the (4n+2) series because each member of the series has a mass equivalent to (4n+2), where n is an integer.

Synonym: uranium-radium series.
Synonym: uranium series.
Related to actinium decay series.
Related to thorium decay series.


uranium-radium series
A synonym for uranium decay series.

uranium series
A synonym for uranium decay series.

x-rays
Photons or electromagnetic radiation produced by the de-excitation of bound atomic electrons. The energy of an x-ray is equivalent to the difference in energy of the initial and final atomic state minus the binding energy of the electron.

Synonym: (Obsolete) x radiation.
Related to electromagnetic radiation.
Related to gamma ray.
Related to photon.
 
 
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