Physics/Electron capture or positron emission
wildwillow wrote at 2007-12-04 23:46:22
The difference is rather simple, electron capture occurs when an electron is, for lack of a better description, pulled into the nucleus where it joins with a proton to form a neutron. As a result, the electrons in the orbitals above the electron which was sucked in (which is in the orbital closest to the nucleus)cascade down the orbitals, and when they do so they release x-rays.
Conversely, positron emission(which to answer your question is very different from electron capture and the reason why they are used interchangeably will be discussed shortly)happens when the nucleus spontaneously emits a positron( in an attempt to become more stable). As a result, it is inevitable that this free positron make it out of the atom without smashing into an electron. After it does so, for a split second in time antimatter is produced, but naturally, this can not be maintained in this universe for even short periods of time, so all of the matter is then transformed( the energy produced can be determined by the use of E=mc^2)into energy, and gamma rays are produced. These rays are photons of energy, which can penetrate nearly anything, excluding something like a wall composed of a few feet of lead.
These two processes seem to be confused or used interchangeably so often due to the fact that both of them are employed by an atom because of an excess amount of protons; both can get rid of protons and as a result, since they do the same thing( although certainly not the same way) they are confused.
Physics Student wrote at 2010-07-24 23:36:37
Actually in a Feynman diagram the antimatter particle (the positron) is considered to move in the opposite direction on the time axis of the diagram. This means that electron capture and positron emission are the same event stated from the viewpoints of an electron and its antimatter positron. However, there is no reported case of a proton decaying. It is impossible because the proton is the smallest of the baryon particles and there is a conservation law for baryon particles. This means that a proton cannot "decay" into other particles do to the lack of available baryons for it to create in its place. The phenomena appears to be the reverse of neutron decay, but an antimatter electron neutrino would also have to be captured, or equally a regular electron neutrino would be emitted.
Emma wrote at 2013-02-03 19:34:58
E-capture is when the nucleus absorbs an electron from its shell and combines this electron with a proton to create a neutron.
Positron emission or beta positive is when a proton decays into a positron (like a positively charged electron) and a neutron, meanwhile releasing gamma rays.