Statistics of charge collection in liquid argon and liquid xenon

There is a fundamental limit to the resolution that can be achieved in liquid-argon and liquid-xenon ionization detectors due to statistical fluctuations in the rate of charge collection along the track of a primary particle. The limit is typically much larger than the resolution expected from Poisson statistics. We present resolution data in both argon and xenon, a model to describe the data, and a discussion of how the model parameters can be manipulated in order to achieve even greater resolution.