In order to develop a new form of spectroscopy, PRECIOSA (Photo-Resonance Excitation and Cavity Ionization Spectroscopy Apparatus), it is necessary to develop a coincidence detector for ions and electrons. When detecting only ions, there is noise that results from ions that do not originate from our deliberate photo-ionization. The addition of a coincidence detector would reduce this noise. I designed such a detector and simulated the detection of ions and electrons originating from the ionization of in-flight particles. These simulations showed a relatively consistent time between detection of each ion and electron, as well as promising location and energy information. These results should help with noise reduction by allowing us to identify which detected ions result from the processes being studied.