Haitz's law is interesting. http://en.wikipedia.org/wiki/Haitz%27s_law http://en.wikipedia.org/wiki/Haitz%27s_law Is it possible to calculate the theoretical m

Haitz's law is interesting. http://en.wikipedia.org/wiki/Haitz%27s_law http://en.wikipedia.org/wiki/Haitz%27s_law Is it possible to calculate the theoretical maximum number of photons that can be produced from a fixed small electron source? Just curious how close we are to maximum theoretical efficiency. 50% ? 80% ?