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Encyclopedia > Internal conversion
Nuclear processes
Radioactive decay processes

Nucleosynthesis OK : Radioactive and Radioactivity redirect here. ... Alpha decay is a form of radioactive decay in which an atomic nucleus ejects an alpha particle through electromagnetic force and transforms into a nucleus with mass number 4 less and atomic number 2 less. ... In nuclear physics, beta decay (sometimes called neutron decay) is a type of radioactive decay in which a beta particle (an electron or a positron) is emitted. ... Cluster decay is the nuclear process in which a radioactive atom emits a cluster of neutrons and protons. ... In the process of beta decay unstable nuclei decay by converting a neutron in the nucleus to a proton and emitting an electron and anti-neutrino. ... Double electron capture is a decay mode of atomic nucleus. ... Electron capture is a decay mode for isotopes that will occur when there are too many protons in the nucleus of an atom, and there isnt enough energy to emit a positron; however, it continues to be a viable decay mode for radioactive isotopes that can decay by positron... This article is about electromagnetic radiation. ... Internal conversion or isomeric transition is the act of returning from an excited state by an atom or molecule. ... Neutron emission is a type of radioactive decay in which an atom contains excess neutrons and a neutron is simply ejected from the nucleus. ... Positron emission is a type of beta decay, sometimes referred to as beta plus (β+). In beta plus decay, a proton is converted to a neutron via the weak nuclear force and a beta plus particle (a positron) and a neutrino are emitted. ... Proton emission (also known as proton radioactivity) is a type of radioactive decay in which a proton is ejected from a nucleus. ... Spontaneous fission (SF) is a form of radioactive decay characteristic of very heavy isotopes, and is theoretically possible for any atomic nucleus whose mass is greater than or equal to 100 amu (elements near ruthenium). ... Nucleosynthesis is the process of creating new atomic nuclei from preexisting nucleons (protons and neutrons). ...

. Internal conversion is a radioactive decay process where an excited nucleus interacts with an electron in one of the lower electron shells, causing the electron to be emitted from the atom. Thus, in an internal conversion process, a high-energy electron which appears to be a classical beta particle is emitted from the radioactive atom, but without beta decay taking place. For this reason, the high-speed electrons from internal conversion are by definition not beta particles, since these are defined by their method of production, not their composition. Also, since no beta decay takes place in internal conversion, the element atomic number does not change (i.e., as in gamma radiation, no transmutation of one element to another takes place in this type of radioactive decay). The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ... Overveiw of the proton-proton chain. ... This article does not cite its references or sources. ... Overview of the Triple-alpha process. ... The carbon burning process is a nuclear fusion reaction that occurs in massive stars (at least 4 MSun at birth) that have used up the lighter elements in their cores. ... Neon burning process is a set of nuclear fusion reactions that take place in massive stars (at least 8 MSun). ... The oxygen burning process is a nuclear fusion reaction that occurs in massive stars that have used up the lighter elements in their cores. ... In astrophysics, silicon burning is a nuclear fusion reaction which occurs in massive stars. ... The process of neutron capture can proceed in two ways - as a rapid process (an r-process) or a slow process (an s-process). ... The R process (R for rapid) is a neutron capture process for radioactive elements which occurs in high neutron density, high temperature conditions. ... This article or section does not cite its references or sources. ... The p process was believed to be a proton capture process which occurrs during supernovae explosions. ... The rp process (rapid proton capture process) consists of consecutive proton captures onto seed nuclei to produce heavier elements. ... In general, spallation is a process in which fragments of material are ejected from a body due to impact or stress. ... OK : Radioactive and Radioactivity redirect here. ... A semi-accurate depiction of the helium atom. ... e- redirects here. ... Alpha radiation consists of helium nuclei and is readily stopped by a sheet of paper. ... In nuclear physics, beta decay (sometimes called neutron decay) is a type of radioactive decay in which a beta particle (an electron or a positron) is emitted. ... Beta particles are high-energy electrons emitted by certain types of radioactive nuclei such as potassium-40. ... In nuclear physics, beta decay (sometimes called neutron decay) is a type of radioactive decay in which a beta particle (an electron or a positron) is emitted. ... This article is about electromagnetic radiation. ...


This internal conversion process is also not to be confused with the more similar photoelectric effect, which also may occur with gamma radiation associated electron emission, in which an incident gamma photon emitted from a nucleus interacts with an electron, expelling the electron from the atom. Gamma photoelectric effect electron emission may also cause high-speed electrons to be emitted from radioactive atoms without beta decay. However, in internal conversion, the nucleus does not first emit an intermediate real gamma ray, and therefore need not change angular momentum or electric moment. Instead, in the internal conversion process, the wavefunction of an inner shell electron penetrates the nucleus (i.e. there is a finite probability of the electron being found in the nucleus) and when this is the case, the electron may couple to the exited state and take the energy of the nuclear transition directly, without an intermediary gamma ray being produced first. Of course, as an electromagnetic process, the process of imparting energy to the electron does take place by means of a virtual photon, but in that sense the photon involved is kind of "virtual gamma ray," which never appears except as a feature of an equation, rather than a measurable particle. The kinetic energy of the emitted electron is equal to the transition energy in the nucleus, minus the binding energy of the electron. A diagram illustrating the emission of photoelectrons from a metal plate, requiring energy gained from an incoming photon to be more than the work function of the material. ... This article is about electromagnetic radiation. ... A diagram illustrating the emission of photoelectrons from a metal plate, requiring energy gained from an incoming photon to be more than the work function of the material. ... In nuclear physics, beta decay (sometimes called neutron decay) is a type of radioactive decay in which a beta particle (an electron or a positron) is emitted. ... This article is about electromagnetic radiation. ... This gyroscope remains upright while spinning due to its angular momentum. ... This article discusses the concept of a wavefunction as it relates to quantum mechanics. ... In the description of the interaction between elementary particles in quantum field theory, a virtual particle is a temporary elementary particle, used to describe an intermediate stage in the interaction. ...


Most internal conversion electrons come from the K shell, as this electron has the highest probability of being found inside the nucleus. After the electron has been emitted, the atom is left with a vacancy in one of the inner electron shells. This hole will be filled with an electron from one of the higher shells and subsequently a characteristic x-ray or Auger electron will be emitted. Auger emission (pronounced ) is a phenomenon in physics in which the emission of an electron from an atom causes the emission of a second electron. ...


Internal conversion is favoured when the energy gap between nuclear levels is small, and is also the only mode of de-excitation for 0+ -> 0+ (i.e. E0) transitions (i.e., where exited nuclei are able to rid themselves of energy without changing electric and magnetic moments in certain ways). It is the predominant mode of de-excitation whenever the initial and final spin states are the same, but the multi-polarity rules for nonzero initial and final spin states do not necessarily forbid the emission of a gamma ray in such a case. In physics, spin refers to the angular momentum intrinsic to a body, as opposed to orbital angular momentum, which is the motion of its center of mass about an external point. ... In electrodynamics, polarization (also spelled polarisation) is the property of electromagnetic waves, such as light, that describes the direction of their transverse electric field. ...


The tendency towards internal conversion can be determined by the internal conversion coefficient, which is empirically determined by the ratio of de-excitations that go by the emission of electrons to those that go by gamma emission. The internal conversion coefficient may be empirically determined by the following formula: = # de-excitations via electron emission / # de-excitations via gamma-ray emission There is no valid conversion coefficient for E0 transitions. ...


  Results from FactBites:
 
Internal conversion - Wikipedia, the free encyclopedia (360 words)
Internal conversion is a radioactive decay process where an excited nucleus interacts with an electron in one of the lower electron shells causing the electron to be emitted.
The internal conversion process is not actually the photoelectric ejection of an atomic electron, as the nucleus does not actually emit a gamma ray in the first place in this process.
The tendency towards internal conversion can be determined by the internal conversion coefficient, which is empirically determined by the ratio of de-excitations that go by the emission of electrons to those that go by gamma emission.
Mills, William Raymond (1955-01-01) Absolute measurements of internal conversion coefficients. ... (384 words)
The combination of conversion electron and gamma yield measurements constitutes an experimental determination of an internal conversion coefficient, and by comparison with theory it is possible to make gamma-ray multipole order assignments.
We have measured the conversion coefficients and found the 1.06-Mev line to be M4 with E2 indicated for the 0.57-Mev line.
We have measured the conversion coefficient of the 440-kev transition and assign it either E1 or M1, the experimental uncertainties preventing a definite assignment.
  More results at FactBites »

 
 

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