I’m simulating an ionization chamber with GARFIELD, where the electric field is imported from COMSOL. An electron-ion pair is generated inside the chamber, with the anode on the top and the bottom electrode consisting of a collector and a guard ring. In theory, electrons should drift to the anode, while positive ions should only reach either the collector or the guard ring — meaning one of the two bottom electrodes should register a charge of e (the elementary charge of an electron) and the other zero. However, in actual simulations, both the collector and guard ring show non-zero charge signals, with their sum always equaling exactly e.
