Outline

1. 75th Annual MeetingMarch 2011Imaging with, spatial resolution of,and plans for upgrading aminimal prototype muon tomography stationJ. LOCKE, W. BITTNER, L. GRASSO,K. GNANVO, and M. HOHLMANNFlorida Institute of Technology, Department of Physics and Space Sciences,150 West University Blvd, Melbourne, FL 32901 0

2. Outline • Motivation • Background • Concept • Origin • Reconstruction algorithm • Voxelization • Prototype • Design • Imaging real targets • Spatial resolution of detectors • Upgrade • Design • Monte Carlo simulation 1

3. Motivation Nuclear contraband is smuggled across borders. Current radiation scanners use gamma and neutron emissions to detect nuclear contraband. About 800 radiation portal monitors in the U.S. Sci. Am., 04/2008 Only 3.25 mm thick lead shielding needed to absorb 99% of gammas emitted by 235U. How can we detect shielded nuclear contraband? 2

4. Muon Tomography Concept Incoming muons (μ±) (from natural cosmic rays) Q=+92e μ Tracking Detector μ Cargo container Q=+26e Θ 235U 92 Θ hidden & shielded high-Z nuclear material 56Fe 26 High-Z material: Big scattering angles! Θ Regular material (low/medium Z): Small scattering angles Θ Note: angles are exaggerated ! Tracking Detector μtracks Idea: Use multiple scattering of charged particles in matter to detect high-Z material 3

5. Origin of Muon Tomography Original idea from Los Alamos (2003): Muon Tomography with Drift Tubes INFN Padova, Pavia & Genova: Muon Tomography with spare CMS Muon Barrel Chambers (Drift Tubes) 4

6. a Reconstruction Algorithm (POCA) Reconstructed Muon Track Matter in the active volume deflects the muon Incoming Vector Point of Closest Approach (POCA) in 3D Space Active Volume θ Scattering Angle Outgoing Vector b 5

7. Voxelization Muon Tracks Muon Tomography Station Detectors Voxels “3D Pixels” (Cubes) Active Volume θ2 θ1 One Voxel Detectors Voxel color indicates mean scattering angle in voxel < θ > 6

8. Minimal Prototype Muon Tomography Station (MTS) with Gas Electron Multiplier (GEM) Detectors 7

9. Minimal MTS Detector 0 Detector 1 Active Volume 30 x 30 cm2 Detector 2 Limited readout electronics allowed only 5 x 5 cm2 to be read out. Detector 3 8

10. Reconstructing the Active Volume Active Volume Voxels 9

11. Min. MTS Reconstruction with Real Data 3 x 3 x 3 cm3 Iron Cube 3 x 2.8 x 3 cm3 Lead Block 10

12. Comparing Real Data to Monte Carlo Simulation Tantalum Cylinder (Real Data) r = 1.5 cm, h = 1.6 cm Ta Cylinder (Monte Carlo Simulation) 11

13. Fit Residuals Reconstructed Muon Path Residual 0 1 Target Support Plate Active Volume 2 3 Detector Hits 12

14. Determining Spatial Resolution 13

15. Determining Spatial Resolution 128.3 µm 14

16. ft3 MTS 15

17. Lateral Detectors Improve Muon Coverage Improve z Resolution ft3 MTS Being assembled at CERN right now! 16

18. ft3 MTS Simulation Reconstruction Ta Pb Fe Same targets imaged with minimal prototype MTS. 17

19. ft3 MTS Simulation Reconstruction (Top view) Fe Pb Ta 18

20. ft3 MTS Simulation Reconstruction 19

21. Summary • Muon tomography can be used to detect shielded nuclear contraband. • Iron, lead, and tantalum blocks were successfully imaged with a minimal prototype muon tomography station. • We estimate our GEM detectors to have 130 µm spatial resolution with preliminary electronics. • The next generation muon tomography station will have improved reconstruction abilities. 20

22. Backup Slides A0

23. Another View of the Minimal MTS A1

24. Another View of the ft3 MTS A2

25. ft3 MTS in the Lab A3

26. Coverage Concept Muon Tracks 3D Voxel 0 0 0 0 1 0 1 0 0 0 0 0 1 1 1 0 0 0 0 0 0 1 1 0 Active Volume 0 0 0 0 0 1 2 0 0 0 0 0 0 0 2 0 Higher coverage → Higher statistics for reconstruction A5