I High Energy Photon Recieved as Lesser Energy Photons?

[Chris Frisella]

Is it possible (and has it been observed) where a single high energy photon is emitted, but then is received as multiple lower energy photons?

 

[MisterX]

This can happen when the photon is absorbed and re-emitted through some "non-linear" materials. See Spontaneous parametric down-conversion.

I don't know if at high photon energies (gamma rays) in vacuum you could get pair production and then recombination producing different number of photons. Maybe someone else can answer that.

 

[mathman]

Pair production requires something in addition to the gamma ray. At high enough density (right after the big bang) it can be photon+photon.

On Earth pair production takes place by interacting with nuclei (necessary for momentum conservation). Typical result is production of electron-positron pair. The positron gets annihilated with an electron to produce two 511 kev photons, which is less than the original gamma ray (> 1022 kev).

 

[Chris Frisella]

Thank you both!