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α
A symbol for alpha particle.

α particle
A synonym for alpha particle.

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.


β
A symbol for beta particle.

β-
A symbol for beta particle.

β+
A symbol for positron.

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.


background
A synonym for background radiation.

background radiation
(1) (general) Radiation that interferes with measurements. Cosmic rays and radioactivity in soil, water and air are forms of ambient radiation that often interferes with low count rate measurements. Other forms of background radiation include sources of radiation observable by the detector, contamination of samples, incomplete absorption of radiation in the detector or incomplete charge collection by the detector.

(2) (10CFR20) Ambient radiation. Radiation from cosmic sources; naturally occurring radioactive materials, including radon (except as a decay product of source material or special nuclear material); and global fallout as it exists in the environment from the testing of nuclear explosive devices. Background radiation does not include radiation from source material, by-product material, or special nuclear materials regulated by the Nuclear Regulatory Commission.

beta
A synonym for beta particle.

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.

Bragg neutron
(obsolete term)

A cathode ray that supposedly picked up enough positive electricity to become neutral. Interaction of the neutron with matter causes the positive electricity to be transferred, leaving the original cathode ray.

Related to neutron.

cold neutron
A neutron with an energy greater than or equal to 5x10-5 eV and less than or equal to 0.025 eV.

Related to continuum region neutron.
Related to epithermal neutron.
Related to fast neutron.
Related to low energy region neutron.
Related to resonance region neutron.
Related to slow neutron.
Related to thermal neutron.
Related to ultra cold neutron.
Related to very cold neutron.


continuum region neutron
A neutron with an energy between 0.01 MeV and 25 MeV.

Related to cold neutron.
Related to epithermal neutron.
Related to fast neutron.
Related to low energy region neutron.
Related to resonance region neutron.
Related to slow neutron.
Related to thermal neutron.
Related to ultra cold neutron.
Related to very cold neutron.


corpuscle
(obsolete term)

It is an early name for the electron, proposed by J. J. Thomson in 1897. It can also be defined as a small particle.

A synonym for electron.

cosmic radiation
Radiation from outer space. Cosmic rays.

d
A symbol for deuteron.

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.


deuteron
The nucleus of the 2H atom. A deuterium nucleus. The deuteron has a mass of 3.3435860(20)x10-27 kg or 2.013553214(24) amu.

Symbol: d.
Synonym: (obsolete)diplon.
Related to deuterium.


diplon
(obsolete term)

A synonym for the deuteron used primarily in Europe.

e+
A symbol for positron.

e-
A symbol for electron.

electron
A basic constituent of the atom. The electron is a fundamental particle that has a mass of 0.000548579903 ± 0.000000000013 atomic mass units (0.51099907 ± 0.00000015 MeV). A free, unbound electron is stable against radioactive decay. The electron is a lepton with a spin of 1/2 and a charge of -1. The positron is the antiparticle of the electron.

Symbol: e-.
Synonym: corpuscle.
Synonym: negative thermion.
Synonym: negaton.
Synonym: negatron.
Related to positron.


electromagnetic radiation
Radiation consisting of interacting electric and magnetic waves. Examples include gamma rays, x-rays, ultraviolet and visible light.

Acronym: EMR.
Synonym: photon.
Related to gamma ray.
Related to infrared radiation.
Related to ionizing radiation.
Related to nonionizing radiation.
Related to particulate radiation.
Related to radiation.
Related to x-ray.


epithermal neutron
A neutron with an energy greater than 0.025 eV and less than or equal to 1 eV.

Related to cold neutron.
Related to continuum region neutron.
Related to fast neutron.
Related to low energy region neutron.
Related to resonance region neutron.
Related to slow neutron.
Related to thermal neutron.
Related to ultra cold neutron.
Related to very cold neutron.


fast neutron
(1) A neutron with an energy considerably greater than thermal energies, sometimes defined as having an energy greater than 1 eV and sometimes defined as having an energy of greater than 100 keV.

(2) A prompt or delayed neutron produced in fission that has not lost appreciable energy.

Related to cold neutron.
Related to continuum region neutron.
Related to epithermal neutron.
Related to low energy region neutron.
Related to resonance region neutron.
Related to slow neutron.
Related to thermal neutron.
Related to ultra cold neutron.
Related to very cold neutron.


fission neutron
A neutron emitted as a nuclide undergoes fission.

Related to delayed fission neutron.
Related to fission.
Related to fission product.
Related to photofission.
Related to prompt fission neutron.
Related to spontaneous fission.
Related to ternary fission.


γ ray
A synonym for gamma ray.

gamma radiation
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-ray.


infrared radiation
Radiation emitted or reflected in the infrared portion of the electromagnetic spectrum.

Related to electromagnetic radiation.
Related to nonionizing radiation.
Related to particulate radiation.
Related to radiation.


ionizing radiation
Any electromagnetic or particulate radiation capable of producing ionization in matter. Examples of ionizing radiation include alpha particles, beta particles, gamma rays x-rays, neutrons, high-speed electrons, high-speed protons, and other particles capable of producing ions. This definition excludes non-ionizing radiation, such as radio- or microwaves, or visible, infrared, or ultraviolet light.

Synonym: ionising radiation.
Related to electromagnetic radiation.
Related to nonionizing radiation.
Related to particulate radiation.
Related to radiation.


low energy region neutron
A neutron with an energy below 1 eV.

Related to cold neutron.
Related to continuum region neutron.
Related to epithermal neutron.
Related to fast neutron.
Related to resonance region neutron.
Related to slow neutron.
Related to thermal neutron.
Related to ultra cold neutron.
Related to very cold neutron.


n
A symbol for neutron.

negaton
(obsolete term)

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

A synonym for electron.

negatron
(obsolete term)

(1) A synonym for electron.
(2) A synonym for beta particle.


Related to positron.

neutron
A basic constituent of the atomic nucleus. The neutron is a fundamental particle, has a mass of 1.008664904 ± 0.000000014 atomic mass units (939.56563 ± 0.00028 MeV). Free, unbound neutrons are produced in fission and in some radioactive decay processes (especially beta decay). A free neutron is unstable, having a half life of 614.6±1.3 s and decaying by β- decay. The neutron is a hadron that is composed of three quarks, udd, and it has a spin-parity of 1/2+ and a magnetic moment of -1.91304275±0.00000045.

Symbol: n.
Related to Bragg neutron.
Related to neutron.
Related to proton.


nonionizing radiation
Electromagnetic or particulate radiation that lacks sufficient energy to remove electrons from the outer shells of atoms.

Related to electromagnetic radiation.
Related to gamma ray.
Related to infrared radiation.
Related to ionizing radiation.
Related to particulate radiation.
Related to radiation. Related to x-ray.


nuclear radiation
Particulate and electromagnetic radiation emitted from atomic nuclei in various nuclear processes. The important nuclear radiations, from the weapon standpoint, are alpha and beta particles, gamma rays, and neutrons. All nuclear radiations are ionizing radiations, but the reverse is not true; x-rays for example, are included among ionizing radiations, but they are not nuclear radiations since they do not originate from atomic nuclei.

p
A symbol for proton.

particulate radiation
Radiation in the form of particles such as electrons, neutrons, alpha particles, and beta particles.

Related to electromagnetic radiation.
Related to gamma ray.
Related to infrared radiation.
Related to ionizing radiation.
Related to nonionizing radiation.
Related to radiation. Related to x-ray.


photon
A quantum of electromagnetic radiation such as a gamma ray or an x-ray. It is a boson and has a mass of 0, a charge of 0 and a spin of 1.

Related to electromagnetic radiation.
Related to gamma ray.
Related to x-ray.


positive electron
A synonym for positron.

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.


primary radiation
Radiation in a system that was not produced as a result of the action of another radiation on that system.

Related to secondary radiation.

prompt fission neutron
A neutron emitted during fission in the formation of the fission fragments.

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


proton
A basic constituent of the atomic nucleus. The proton is a fundamental particle, has a mass of 1.007276470 ± 0.000000012 atomic mass units (938.27231 ± 0.00028 MeV). Chemical elements are defined by the number of protons in the nucleus, which is equal to the atomic number of that element. Free, unbound protons are stable with respect to radioactive decay with the lower limit of their half life as 1.1x1025 yr. The proton is a hadron that is composed of three quarks, uud, and it has a spin-parity of 1/2+ and a magnetic moment of +2.792847386 ± 0.000000063.

Symbol: p.
Related to atomic number.
Related to electron.
Related to neutron.
Related to nucleon.


radiation
Often a synonym for ionizing radiation. Generally this includes alpha particles, beta particles, gamma rays x-rays, neutrons, high-speed electrons, high-speed protons, and other particles capable of producing ions. Radiation, as used in 10CFR part 20, does not include non-ionizing radiation, such as radio- or microwaves, or visible, infrared, or ultraviolet light.

Related to electromagnetic radiation.
Related to gamma ray.
Related to infrared radiation.
Related to ionizing radiation.
Related to nonionizing radiation.
Related to particulate radiation.
Related to x-ray.


resonance region neutron
A neutron with an energy between 1 eV and 0.01 MeV.

Related to cold neutron.
Related to continuum region neutron.
Related to epithermal neutron.
Related to fast neutron.
Related to low energy region neutron.
Related to slow neutron.
Related to thermal neutron.
Related to ultra cold neutron.
Related to very cold neutron.


secondary radiation
Radiation produced by the interaction of a charged particle or other radiation with matter.

Related to primary radiation.

slow neutron
A neutron with an energy below 1 eV.

Related to cold neutron.
Related to continuum region neutron.
Related to epithermal neutron.
Related to fast neutron.
Related to low energy region neutron.
Related to resonance region neutron.
Related to thermal neutron.
Related to ultra cold neutron.
Related to very cold neutron.


t
A symbol for triton.

thermal neutron
A neutron with an energy approximately equal to 0.025 eV.

Related to cold neutron.
Related to continuum region neutron.
Related to epithermal neutron.
Related to fast neutron.
Related to low energy region neutron.
Related to resonance region neutron.
Related to slow neutron.
Related to ultra cold neutron.
Related to very cold neutron.


triton
The nucleus of tritium, 3H.

Symbol: t.
Related to tritium.


ultra cold neutron
A neutron with an energy less than 2x10-7 eV.

Related to cold neutron.
Related to continuum region neutron.
Related to epithermal neutron.
Related to fast neutron.
Related to low energy region neutron.
Related to resonance region neutron.
Related to slow neutron.
Related to thermal neutron.
Related to very cold neutron.


very cold neutron
A neutron with an energy greater than or equal to 2x10-7 eV and less than 5x10-5 eV.

Related to cold neutron.
Related to continuum region neutron.
Related to epithermal neutron.
Related to fast neutron.
Related to low energy region neutron.
Related to resonance region neutron.
Related to slow neutron.
Related to thermal neutron.
Related to ultra cold neutron.


x-ray
A photon or electromagnetic radiation produced by the de-excitation of a bound atomic electron. 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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