How to calculate the Electron transparency of a GEM foil?
How to find the number of electrons entering in the hole and number of electrons heading towards readout?
To simulate the electron transparency you can start with a single electron in the drift gap, simulate an avalanche using e. g. AvalancheMicroscopic (see https://garfieldpp.web.cern.ch/examples/gem/), loop over the “endpoints” (=electron trajectories) in the avalanche and count how many electrons (if any) end up in the induction gap.