gamma rays and photons

[wormboge]

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I am seeing gamma ray emission modeled as, electron + positron --> gamma symbol + gamma symbol. First of all, what do the gamma symbols mean in this context? How much of a gamma ray could a single collision of just one electron and just one positron produce? How would that be measured?

This may be a little beyond the scope of the MCAT, but while studying for the MCAT, I began to wonder how the approximate number of photons in a gamma ray is measured?

 

[pretty_positron]

There isn't really a ceiling to the energies for gamma rays, so it can be difficult to say for certain. For an electron at rest to collide with an annihilate a positron at rest, the conversion of energy will produce 2 gamma ray photons.

If those electrons and/or positrons had kinetic energy to them, that will have to be conserved and converted to a larger number of gamma rays.

How many exactly? Unfortunately, with gamma rays, there isn't quite a ceiling. The range is quite vast.

The floor is what X-Rays are which is 100+ keV, while gamma rays can be a few keV to ~10 MeV. This is just the low-end by the way, where you can still see line spectra and thus photons at discrete energies. Gamma rays can reach up to 1 TeV as seen in astrophysics.

Hell, particle accelerators can add so much kinetic energy that they can produce D mesons or B mesons.