1. Monte Carlo simulations of a first prototype micropattern gas detector system used for muon tomography J. B. Locke, K. Gnanvo, M. Hohlmann Department of Physics and Space Sciences, Florida Institute of Technology Simulation Data Conclusion Acknowledgements Concept MethodsObjective We seek to build a system using cosmic ray muons to detect nuclear materials—such as Uranium—smuggled through borders in shipping containers, trucks, etc. for terrorism or other malicious purposes. Energy and Other Particles ±± ±± ∓∓ ∓∓ Scattering Point Data Analysis (x,y,z) of Detector Hits  Muon Detector High-energy p + Upper Atmosphere Nucleus Nuclear Reaction Cosmic rays (such as high-energy protons from the Sun) strike nuclei in the upper atmosphere, emitting particles and energy. Pions are emitted. These pions decay into muons in the upper atmosphere. The muons make it to Earth’s surface. Muons are similar to electrons, but about 200 times as massive. The muons are detected by gas electron multiplier (GEM) detectors. The details of how these detectors operate are many, so they will not be presented here. The muon is scattered in the detector by some matter. The greater the scattering angle, the higher the atomic number of the matter. The incoming and outgoing vectors of the muon are found to intersect at the scattering point. At sea level, cosmic ray muons have a flux of about 10,000 muons/m 2 /minute and average energies of 4 GeV. This is sufficient flux and energy to detect and use these muons. This flux and a muon detection and tomography system are simulated using the Monte Carlo simulation utility, GEANT4. We simulate scenarios such as the one shown below with a truck with nuclear material as cargo. Below the truck is the reconstruction of scattering points for the muons. The color of a point is indicative of the scattering angle. Scattering Angle [degrees] Position (x,y,z) [mm] Engine Targets (U, Pb, etc.) We have constructed a muon tomography system composed of 4 detectors with a detection area of 30x30 cm 2. However, we can only read out 5x5 cm 2 of the detectors due to electronics limitations. The target is a lead block of 3x3x2 cm 3. The data from this prototype is still being analyzed. However, I will present simulation data from this detector system. Position (x,y,z) [mm] Scattering Angle [degrees] Mean Scattering Angle [degrees] Left: A 3D reconstruction of scattering points from the scenario with a 3x3x2 cm 3 block of lead and 5x5 cm 2 detectors exposed to a natural flux of muons for 24 hours. The lead block is somewhat visible in the center of the detector volume. Right: A 2D slice of the 3D reconstruction shown above. The slice is taken for 5 mm ≤ z ≤ 15 mm. The values shown for each square are averages of the scattering angles for all scattering points contained in the 3D voxel. This slice is directly above the target. Clearly, the lead target is quite visible. Muon tomography seems to be a promising technique for detecting materials with high densities and/or atomic numbers. Simulations show our prototype muon tomography system can detect a small piece of lead after 24 hours exposure to a natural muon flux. However, the reality of muon tomography is much more complicated than our simulations currently achieve. Data was taken with the prototype detector system in early February and is still being analyzed. The data, diagrams, and information on this poster are products and/or property of the high-energy physics research group at the Florida Institute of Technology. Thanks to Kondo Gnanvo, Amilkar Quintero, and others whose work has made this research possible and the muon detector a reality.