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Prototype of a Muon Tomography Station with GEM Detectors for Detection of Shielded Nuclear Contraband. Michael Staib 1 V. Bhopatkar 1 , W. Bittner 1 , K. Gnanvo 1,2 , L. Grasso 1 , M. Hohlmann 1 , J. B. Locke 1 , J. Twigger 1 1 Dept. of Physics & Space Sciences, Florida Institute of Technology
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Prototype of a Muon Tomography Station with GEM Detectors for Detection of Shielded Nuclear Contraband Michael Staib1 V. Bhopatkar1, W. Bittner1, K. Gnanvo1,2, L. Grasso1, M. Hohlmann1, J. B. Locke1, J. Twigger1 1Dept. of Physics & Space Sciences, Florida Institute of Technology 2 now at University of Virginia 2012 April APS Meeting, Atlanta, GA
Outline Outline Muon Tomography Cubic-foot MTS with GEMs Experimental Results Future Work • Concept of Muon Tomography and previous work. • Prototype cubic-foot Muon Tomography Station (MTS) with GEM Detectors. • The Gas Electron Multiplier (GEM) detector. • DAQ electronics and analysis software. • Experimental tomographic reconstructions of shielded and unshielded high-Z materials using this prototype.
Outline Muon Tomography Cubic-foot MTS with GEMs Experimental Results Future Work Muon Tomography Concept Incoming muons (from natural cosmic rays) μ μ μ μ Uranium Iron μ μ Fe U Tracking detectors Small Scattering Large Scattering Small Scattering Large Scattering Multiple Coulomb scattering to 1st order produces Gaussian distribution of scattering angles θwith width σ = Θ0: Note: Angles Exaggerated! Object Reconstruction Algorithm Point of Closest Approach (POCA)
CMS Outline Muon Tomography Cubic-foot MTS with GEMs Experimental Results Future Work Muon Tomography with Drift Tubes INFN Pb W Brass Cu Fe Al Reconstruction of 1 inch thick Pb letters 4.3 m 1.4 m 3 2 1 Original idea from Los Alamos (2003): Muon Tomography with Drift Tubes INFN : Muon Tomography with spare CMS Muon Barrel Chambers (Drift Tubes) Decision Sciences Int’l Corp.: Multi-Mode Passive Detection System, MMPDSTM from Decision Sciences public web pages J.A. Green, et al., “Optimizing the Tracking Efficiency for Cosmic Ray Muon Tomography”, LA-UR-06-8497, IEEE NSS 2006. S. Presente, et al., Nucl. Inst. and Meth. A 604 (2009) 738-746.
Compact Cubic-Foot Muon Tomography Station Using GEMs Outline Muon Tomography Cubic-foot MTS with GEMs Experimental Results Future Work Plastic Scintillator (Trigger) Triple-GEM Detector 1 ft3 active volume 30 cm
Gas Electron Multiplier (GEM) Detector Outline Muon Tomography Cubic-foot MTS with GEMs Experimental Results Future Work V GEM foil under electron microscope ~400 V μ- e- M.C Altunbas, et al., Nucl. Inst. and Meth. A 515 (2003) 249-254. F. Sauli, Nucl. Inst. and Meth. A 386 (1997) 531-534. Gas Gain ~ O(104)
Outline Muon Tomography Cubic-foot MTS with GEMs Experimental Results Future Work Triple-GEM Detector for MT station • 30 cm x 30 cm triple-GEM detectors • Follows design for COMPASS at CERN • Ar/CO2 70:30 mixture • X-Y Cartesian readout @ 400 μm pitch • ~50 µm spatial resolution for perpendicular tracks • Compact detector, low material budget Drift Cathode GEM foil FR4 Spacer Frame 400 μm 80 μm X-Y Readout 400 μm 340 μm Readout Strips (bottom layer) Assembled GEM Detector Readout Strips (top layer) Insulating Layer Support COMPASS Design Nucl. Inst. and Meth. A 490 (2002) 177–203
DAQ Electronics Outline Muon Tomography Cubic-foot MTS with GEMs Experimental Results Future Work • Scalable Readout System (SRS) developed by the RD51 collaboration at CERN. • Currently 11 teams using SRS for different applications using MPGDs. • Florida Tech is currently the largest user with ~12k channels of analog readout. HDMI Gb Ethernet APV25 Hybrid ADC FEC • 128 channel APV25 chip • 192-deep analog sampling memory • Master/slave configuration • Diode protection against discharge • RD51 standard 130-pin Panasonic connector interfaces to detector • HDMI mini (type C) connector DAQ Computer • 2 x 12-Bit Octal ADC • 8 x HDMI input channels (16 APV hybrids) • Virtex LX50T FPGA • SFP/Gb Ethernet/DTC interface • NIM/LVDS GPIO (trigger, clock synch, etc.) • Data Acquisition using DATE (ALICE @ CERN) • Support added for data transfer via UDP • Slow control via ethernet • Online and offline analysis using custom package for AMORE (ALICE @ CERN)
Detector Characterization using AMORE 2D Hit Map Charge Sharing Signal to Noise Ratio Note: Crossed structure due to spacer frames Cluster Multiplicity Cluster Size Cluster Charge Distribution Mean = 1.2 Clusters Mean = 4.7 Strips
Material Discrimination: Scenario Outline Muon Tomography Cubic-foot MTS with GEMs Experimental Results Future Work Lead Z = 82 Density = 11.3 g/cm3 Tungsten Z = 74 Density = 19.3 g/cm3 Depleted Uranium Z = 92 Density = 19.1 g/cm3 6mm Al shielding Iron Z = 26 Density = 7.9 g/cm3 Tin Z = 50 Density = 5.8 g/cm3
Material Discrimination: Result Outline Muon Tomography Cubic-foot MTS with GEMs Experimental Results Future Work Lead Tungsten Tin Iron Uranium -55 mm < z < -15 mm Min. # of muon per voxel = 2 Voxel Size: 2 x 2 x 40 mm3 Simple Scattering Density (Degrees / cm3) 155,104 Reconstructed Tracks
Material Discrimination: Result XZ Slices U Sn Fe Pb W +Y +X Pb W -70 mm < Y < -30 mm -20 mm < Y < 20 mm 30 mm < Y < 70 mm YZ Slices Fe Sn Sn Pb U Fe W -70 mm < X < -30 mm -20 mm < X < 20 mm 30 mm < X < 70 mm 155,104 Reconstructed Tracks
Outline Muon Tomography Cubic-foot MTS with GEMs Experimental Results Future Work Uranium with Brass Shielding The shielded uranium block can clearly be seen in the reconstruction 187,731 Reconstructed Tracks 40 mm XY slices with Z decreasing by 5mm each frame
Outline Muon Tomography Cubic-foot MTS with GEMs Experimental Results Future Work Future Work • Increase the number of GEM detectors per tracking module to improve reconstruction. • Redesign support structure to allow more freedom in detector orientation. • Implement statistical reconstruction methods and POCA clustering algorithms. • Improve tracking and sensor alignment methods in the AMORE analysis package. • Include a measurement of muon momentum in the reconstruction. • Scale up! (Next goal is ~1 m3 active volume)
Thanks! Questions? Disclaimer: This material is based upon work supported in part by the U.S. Department of Homeland Security under Grant Award Number 2007-DN-077-ER0006-02. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U.S. Department of Homeland Security.
Image Resolution Study: Imaging a gap separating W and Pb blocks 0 mm 2 mm 4 mm 115,834 muons 94,719 muons 111,036 muons 6 mm 8 mm 107,506 muons 121,634 muons
Scattering Density (deg/cm3) 0 mm 2 mm 4 mm 6 mm 8 mm Analysis Region Statistically significant signal with 8mm spacing