Nucleosynthesis Radioactive decay is the set of various processes by which unstable atomic nuclei (nuclides) emit subatomic particles. ... Alpha decay is a form of radioactive decay in which an atomic nucleus ejects an alpha particle 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. ... Electron capture is a decay mode for chemical elements that will occur when there are too many protons in the nucleus of an atom, and there isnt enough energy to emit a positron. ... This article is about electromagnetic radiation. ... 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 the 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 either by nuclear fusion or nuclear fission. ...
Neutron Capture
The R-process
The S-process
Proton capture:
The P-process
Internal conversion or isomeric transition is the act of returning from an excited state by an atom or molecule. The R process (R for rapid) is a neutron capture process for radioactive elements which occurs in high neutron density, high temperature conditions. ... The S process (S for slow) is a neutron capture process in the decay of radioactive elements that occurs in lower neutron density, lower temperature conditions. ... The p process was believed to be a proton capture process which occurrs during supernovae explosions. ... In quantum mechanics, an excited state of a system (such as an atom, molecule or nucleus) is any configuration of the system that has a higher energy than the ground state (that is, more energy than the absolute minimum). ... Properties For alternative meanings see atom (disambiguation). ... In science, a molecule is the smallest particle of a pure chemical substance that still retains its chemical composition and properties. ...
Nuclear Internal Conversion
This is an alternative to gamma-ray emission, which is the usual method for an excited nucleus to return to the ground state. In internal conversion, the excited nucleus transfers its energy directly to one of the most tightly bound electrons causing it to be ejected from the atom. After the ejection of the internal conversion electron the vacancy is filled by another shell electron and the atom ejects one or several x-rays or Auger electrons. Gamma rays (often denoted by the Greek letter gamma, γ) are an energetic form of electromagnetic radiation produced by radioactivity or other nuclear or subatomic processes such as electron-positron annihilation. ... The nucleus (atomic nucleus) is the center of an atom. ... Properties The electron is a subatomic particle. ... In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz... When an electron is removed from a core level of an energy. ...
Internal conversion is favored when the energy gap between nuclear levels is small, and is also the only mode of de-excitation for 0+ -> 0+ (ie. E0) transitions. It is the predominant mode of de-excitation whenever the initial and final spin states are the same, but the multipolarity rules for nonzero initial and final spin states do not necessarily forbid the emission of a gamma ray in such a case.
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. ...
A nuclear isomer is a metastable or isomeric state of an atom caused by the excitation of a proton or neutron in its nucleus so that it requires a change in spin before it can release its extra energy.
Another reasonably stable nuclear isomer (with a half-life of 31 years) is hafnium-178m, which has the highest excitation energy of any stable isomer.
As of 2005 the claims that hafnium isomers can be used as potential energy storage devices or even weapons is generally regarded with derision in the general scientific community and future prospects for the idea's vindication appear very dim.
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