Microscopic simulation of xenon-based optical TPCs in the presence of molecular additives

We introduce a simulation framework for the transport of high and low energy electrons in xenon-based gaseous optical time projection chambers(OTPCs). The simulation relies on elementary cross sections (electron-atom and electron-molecule) and incorporates, in order to compute the gas scintillation, the reaction/quenching rates (atom-atom and atom-molecule) of the first 41 excited states of xenonand the relevant associated excimers, together with their radiative cascade. The results compare positively with observations made in pure xenonand its mixtures with CO$_2$ and CF$_4$ in a range of pressures from 0.1 to 10~bar. This work sheds some light on the elementary processes responsible for the primary and secondary xenon-scintillation mechanisms in the presence of additives, that are of interest to the OTPC technology.