Design, Testing, and Results of Gas Electron Multiplier Detectors for Muon Ray Tomography Imaging Alfred Menendez, Michael Abercrombie, Amilkar Quintero, Kondo Gnanvo. Adviser: Dr. Hohlmann. Florida Tech, Physics and Space Sciences Department Theory: This is a diagram of what a single GEM detector looks like. The detector that I am currently working with is similar, except that it has three GEM foils in one detector. An incoming muon ionizes the ArCO2 gas mixture inside the detector and releases an electron or two, those electrons are then channeled via a potential difference into the holes in the GEM foil and ionize more gas releasing more of the electrons. The reason that three foils are used is because it allows for a greater electron avalanche to create a higher amplification. The electrons finally reach an x-y readout board where the 2-D coordinate is recorded.