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Encyclopedia > Positron emission
Nuclear processes
Radioactive decay processes

Nucleosynthesis Radioactive decay is the set of various processes by which unstable atomic nuclei (nuclides) emit subatomic particles (radiation). ... 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. ... Double electron capture is a decay mode of atomic nucleus. ... 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; however, it continues to be a viable decay mode for radioactive elements that can decay by... This article is about electromagnetic radiation. ... This article is about the nuclear process. ... 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. ... 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 either by nuclear fusion or nuclear fission. ...

  • Neutron Capture
    • The R-process
    • The S-process
  • Proton capture:
    • The P-process

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. Isotopes which emit positrons include Carbon-11, Nitrogen-13, Oxygen-15 and Fluorine-18; for example: 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. ... Properties In physics, the proton (Greek proton = first) is a subatomic particle with an electric charge of one positive fundamental unit (1. ... Properties In physics, the neutron is a subatomic particle with no net electric charge and a mass of 939. ... The weak nuclear force or weak interaction is one of the four fundamental forces of nature. ... A particle emitted by beta plus decay. ... The first detection of the positron in 1932 by Carl D. Anderson The positron is the antiparticle or the antimatter counterpart of the electron. ... The neutrino is an elementary particle. ... General Name, Symbol, Number carbon, C, 6 Chemical series nonmetals Group, Period, Block 14, 2, p Appearance black (graphite) colorless (diamond) Atomic mass 12. ... ... General Name, Symbol, Number oxygen, O, 8 Chemical series Chalcogens Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ... General Name, Symbol, Number fluorine, F, 9 Chemical series halogens Group, Period, Block 17, 2, p Appearance pale greenish-yellow gas Atomic mass 18. ...

These isotopes are used in positron emission tomography, a technique used for medical imaging. Image of a typical positron emission tomography (PET) facility Positron emission tomography (PET) is a nuclear medicine medical imaging technique which produces a three dimensional image or map of functional processes in the body. ...


Electron capture is a competing decay mode in this process and is energetically favoured, but as the energy difference goes up so does the branching ratio towards positron emission. 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; however, it continues to be a viable decay mode for radioactive elements that can decay by...


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