How does one see the effect of a single electron?

Suppose the potential between each dynode in our photomultiplier tube is 80V. From the relationship we found from our last plot, this would mean that two secondary electrons would be emitted for each incident electron at each dynode. Suppose a photon has struck the photocathode of the photomultiplier tube and has emitted the initial photoelectron. What will happen when this electron strikes the first dynode?