I'm trying to understand a section of a paper. They're talking about the signal generated by a photomultiplier tube when photons from fluorescence are coming into it. The sentence says, "Since the number of photo-electrons ultimately captured by the PMT is finite, the signal quantitation is stochastic with a variance governed by the Poisson distribution."
- Why does the fact that the number of photo-electrons is finite affect anything?
- I forgot what stochastic means, please enlighten me.
- Does "signal quantitation" mean the number of distinct waveforms coming out of the PMT?
- Why is it governed by the Poisson distribution?
The next sentence says, "The square root of the number of captured photo-electrons is approximately the standard deviation of the error distribution." Is this because it is Poisson?
Also, explain the following sentences to me please: "Q is a measurement of efficiency and has units of number of photo-electrons per unit fluorescence intensity. The lower the Q value, the higher the amount of relative counting error associated with the signal."
I will admit that the primary reason I don't understand this is that I slacked off in prob/stat classes and I also never really learned how a PMT works. Unfortunately now it's important for me to understand what's going on!