75 th Annual Meeting March 2011 Imaging with, spatial resolution of, and plans for upgrading a...
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Transcript of 75 th Annual Meeting March 2011 Imaging with, spatial resolution of, and plans for upgrading a...
75th Annual MeetingMarch 2011
Imaging with, spatial resolution of,and plans for upgrading a
minimal prototype muon tomography station
J. LOCKE, W. BITTNER, L. GRASSO,K. GNANVO, and M. HOHLMANN
Florida Institute of Technology, Department of Physics and Space Sciences,150 West University Blvd, Melbourne, FL 32901 0
Outline• Motivation• Background– Concept– Origin– Reconstruction algorithm– Voxelization
• Prototype– Design– Imaging real targets– Spatial resolution of detectors
• Upgrade– Design– Monte Carlo simulation
1
Motivation
Only 3.25 mm thick lead shielding needed to absorb 99% of gammas emitted by 235U.
How can we detect shielded nuclear contraband?
Sci. Am., 04/2008
Nuclear contraband issmuggled across borders.
Current radiation scannersuse gamma and neutronemissions to detect nuclearcontraband.
About 800 radiation portalmonitors in the U.S.
2
Muon Tomography Concept
56FeΘ
Θ
Incoming muons (μ±)
μ
Θ
Θ
Note: angles are exaggerated !
(from natural cosmic rays)
Cargo container
hidden &shieldedhigh-Znuclearmaterial
μ tracks
Regular material (low/medium Z):Small scattering angles
High-Z material: Big scattering angles!
μQ=+92e
Q=+26e
235U92
26
Tracking Detector
Idea: Use multiple scattering of charged particles in matter to detect high-Z material
Tracking Detector
3
Origin of Muon TomographyOriginal 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
Reconstruction Algorithm (POCA)Ac
tive
Volu
me
θ
Point of Closest Approach
(POCA)in 3D Space
a
b
Incoming Vector
Outgoing V
ector
Reconstructed Muon Track
Matter in the active volume deflects the
muon
Scattering Angle
5
Voxelization
Detectors
Voxels“3D Pixels”(Cubes)
Detectors
One Voxel
Muon Tracks
θ1
θ2
Voxel color indicatesmean scattering angle in voxel
< θ > 6
Activ
e Vo
lum
e
Muon Tomography Station
Minimal PrototypeMuon Tomography Station (MTS)
withGas Electron Multiplier (GEM) Detectors
7
Detector 0
Active Volume
Detector 1
Detector 2
Detector 3
Minimal MTS
Limited readout electronics allowed only 5 x 5 cm2 to be read out.
30 x 30 cm2
8
Active Volume
Reconstructing the Active Volume
Voxels
9
Min. MTS Reconstruction with Real Data3 x 3 x 3 cm3 Iron Cube 3 x 2.8 x 3 cm3 Lead Block
10
Comparing Real Data to Monte Carlo SimulationTantalum Cylinder (Real Data) Ta Cylinder (Monte Carlo Simulation)r = 1.5 cm, h = 1.6 cm
11
0
1
2
3
Target Support Plate Active Volume
Residual Reconstructed Muon Path
Detector Hits
Fit Residuals
12
Determining Spatial Resolution
13
128.3 µm
Determining Spatial Resolution
14
ft3 MTS
15
ft3 MTSBeing assembled
at CERN right now!
Lateral DetectorsImprove Muon Coverage
Improve z Resolution
16
FePbTa
ft3 MTS Simulation Reconstruction
Same targets imaged withminimal prototype MTS.
17
Fe
Pb
Ta
ft3 MTS Simulation Reconstruction (Top view)
18
ft3 MTS Simulation Reconstruction
19
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
Backup Slides
A0
Another View of the Minimal MTS
A1
Another View of the
ft3 MTS
A2
ft3 MTS in the Lab
A3
Coverage Concept
Active Volume
3D Voxel
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
0
0
0
0
1
1
1
0
1
1
1
2
2
0
0
0
0
0
Higher coverage → Higher statistics for reconstruction
Muon Tracks
A5