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
• 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.
Future Work
Muon Tomography Concept
Muon Tomography
Incoming muons
cosmic rays)
μ (from natural μ
μ
μ
Outline
Cubic-foot MTS with GEMs
Experimental Results
Uranium
Iron μ
μ
Small
Scattering
Note: Angles
Exaggerated!
Future Work
Fe
U
Large
Scattering
Small
Large
Scattering Scattering
Tracking
detectors
Multiple Coulomb scattering to 1st order produces Gaussian
distribution of scattering angles θ with width σ = Θ0:
Object
0 
13.6 MeV
cp
x
1
[1  0.038ln(x / X 0 )] with
 Z ( Z  1)
X0
X0
Reconstruction Algorithm
Point of Closest Approach
(POCA)

Outline
Muon Tomography with Drift Tubes
Muon Tomography
Pb W
Brass Cu
Cubic-foot MTS with GEMs
INFN
Experimental Results
Fe
Al
Future Work
Reconstruction of 1 inch thick Pb letters
CMS
1.4 m
4.3 m
3
1
Original idea from Los Alamos (2003):
Muon Tomography with Drift Tubes
J.A. Green, et al., “Optimizing the Tracking
Efficiency for Cosmic Ray Muon Tomography”,
LA-UR-06-8497, IEEE NSS 2006.
2
INFN : Muon Tomography with spare CMS
Muon Barrel Chambers (Drift Tubes)
Decision Sciences Int’l Corp.: Multi-Mode
Passive Detection System, MMPDSTM
S. Presente, et al., Nucl. Inst. and Meth.
A 604 (2009) 738-746.
from Decision Sciences public web pages
Compact Cubic-Foot
Muon Tomography Station Using GEMs
Outline
Muon Tomography
Cubic-foot MTS with GEMs
Experimental Results
Future Work
Plastic Scintillator (Trigger)
1 ft3
active
volume
30 cm
Triple-GEM Detector
Gas Electron Multiplier (GEM) Detector
Outline
Muon Tomography
GEM foil under electron microscope
Cubic-foot MTS with GEMs
V
Experimental Results
Future Work
~400 V
μe-
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
Triple-GEM Detector for MT station
Drift Cathode
GEM foil
•
30 cm x 30 cm triple-GEM detectors
Muon Tomography
•
Follows design for COMPASS at CERN
Cubic-foot MTS with GEMs
•
Ar/CO2 70:30 mixture
Experimental Results
•
X-Y Cartesian readout @ 400 μm pitch
Future Work
•
~50 µm spatial resolution for perpendicular
tracks
•
Compact detector, low material budget
FR4 Spacer Frame
400 μm
80 μm
X-Y Readout
Readout Strips
(bottom layer)
Insulating Layer
COMPASS Design
Readout Strips
(top layer)
Support
Nucl. Inst. and Meth. A 490 (2002) 177–203
Assembled GEM Detector
Outline
DAQ Electronics
Muon Tomography
•
•
•
Scalable Readout System (SRS) developed by the RD51 collaboration at CERN. Cubic-foot MTS with GEMs
Currently 11 teams using SRS for different applications using MPGDs.
Florida Tech is currently the largest user with ~12k channels of analog readout. Experimental Results
Future Work
HDMI
APV25 Hybrid
•
•
•
•
•
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
Gb Ethernet
ADC
FEC
• 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.)
DAQ Computer
•
•
•
•
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
Mean = 1.2 Clusters
Mean = 4.7 Strips
Cluster Charge Distribution
Material Discrimination: Scenario
Outline
Muon Tomography
Cubic-foot MTS with GEMs
Lead
Z = 82
Density = 11.3 g/cm3
Depleted Uranium
Z = 92
Density = 19.1 g/cm3
Tungsten
Z = 74
Density = 19.3 g/cm3
6mm Al shielding
Tin
Z = 50
Density = 5.8 g/cm3
Iron
Z = 26
Density = 7.9 g/cm3
Experimental Results
Future Work
Material Discrimination: Result
Outline
Muon Tomography
Lead
Tungsten
Cubic-foot MTS with GEMs
Experimental Results
Future Work
Tin
Iron
Uranium
Voxel Size: 2 x 2 x 40 mm3
-55 mm < z < -15 mm
Min. # of muon per voxel = 2
Simple Scattering Density (Degrees / cm3)
Uranium
Tungsten
Lead
Tin
Iron
157.8
115.3
101.0
68.9
61.3
155,104 Reconstructed Tracks
Material Discrimination: Result
XZ Slices
Sn
Fe
U
Pb
W
+Y
+X
-70 mm < Y < -30 mm
-20 mm < Y < 20 mm
30 mm < Y < 70 mm
Pb
W
Sn
Fe
YZ Slices
Sn
Pb
-70 mm < X < -30 mm
U
-20 mm < X < 20 mm
Fe
W
30 mm < X < 70 mm
155,104 Reconstructed Tracks
Uranium with Brass Shielding
Outline
Muon Tomography
Cubic-foot MTS with GEMs
Experimental Results
Future Work
The shielded uranium
block can clearly be
seen in the
reconstruction
40 mm XY slices with Z decreasing by 5mm each frame
187,731 Reconstructed Tracks
Future Work
Outline
Muon Tomography
Cubic-foot MTS with GEMs
• Increase the number of GEM detectors per tracking module to
improve reconstruction.
Experimental Results
Future Work
• 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.
Backup Slides
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
6 mm
8 mm
Statistically significant signal with 8mm spacing
4 mm
Analysis Region