Recent advancements in the field of positron remoderation and improvements to the Penning-Malmberg trap have made it possible to produce high density bursts of positrons in a magnetic field-free region which will allow us to study high density collections of many positrons. In this thesis, we outline and propose an experiment to detect the positronium plus ion for the first time and to measure its lowest energy Feshbach resonance using UV photon-excitation. The implications and challenges of this experiment are discussed.