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 Technology2 now at University of Virginia

2012 April APS Meeting, Atlanta, GA

Outline

• 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 Outline

Muon Tomography

Cubic-foot MTS with GEMs

Experimental Results

Future Work

μμ

Fe ULarge

ScatteringSmall

Scattering

μIron

Small Scattering

Uraniumμ

LargeScattering

μμIncoming muons (from natural cosmic rays)

Note: Angles Exaggerated!

)1( 1

with )]/ln(038.01[MeV6.13

00

0

0 ZZX

XxX

x

cp

Tracking detectors

Reconstruction AlgorithmPoint of Closest Approach

(POCA)

Object

Multiple Coulomb scattering to 1st order produces Gaussian distribution of scattering angles θ with width σ = Θ0:

Muon Tomography with Drift Tubes Outline

Muon Tomography

Cubic-foot MTS with GEMs

Experimental Results

Future Work

CMSCMS

Brass Cu

Pb W

Fe

Al

Original idea from Los Alamos (2003): Muon Tomography with Drift Tubes

Reconstruction of 1 inch thick Pb letters

J.A. Green, et al., “Optimizing the Tracking Efficiency for Cosmic Ray Muon Tomography”, LA-UR-06-8497, IEEE NSS 2006.

INFN : Muon Tomography with spare CMS Muon Barrel Chambers (Drift Tubes)

S. Presente, et al., Nucl. Inst. and Meth. A 604 (2009) 738-746.

1.4 m1.4 m4.3 m4.3 m

1122

33

Decision Sciences Int’l Corp.: Multi-Mode Passive Detection System, MMPDSTM

from Decision Sciences public web pages

INFN

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 Detector1 ft3

active

volume

30 cm

Gas Electron Multiplier (GEM) Detector

V

μ-

e-

GEM foil under electron microscope

~400 V

Gas Gain ~ O(104)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.

Outline

Muon Tomography

Cubic-foot MTS with GEMs

Experimental Results

Future Work

• 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

Triple-GEM Detector for MT station

COMPASS Design

Assembled GEM Detector

Drift Cathode

GEM foil

FR4 Spacer Frame

X-Y Readout

Nucl. Inst. and Meth. A 490 (2002) 177–203

Insulating Layer Readout Strips(top layer)

Support

Readout Strips(bottom layer)

400 μm

400 μm

340 μm

80 μm

Outline

Muon Tomography

Cubic-foot MTS with GEMs

Experimental Results

Future Work

DAQ Electronics

• 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.

Outline

Muon Tomography

Cubic-foot MTS with GEMs

Experimental Results

Future Work

HDMIGb Ethernet

APV25 HybridADC 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

• 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

Note: Crossed structure due to spacer frames

Charge Sharing2D Hit Map

Cluster SizeCluster Multiplicity Cluster Charge Distribution

Signal to Noise Ratio

Mean = 1.2 Clusters Mean = 4.7 Strips

Material Discrimination: Scenario

LeadZ = 82

Density = 11.3 g/cm3Depleted Uranium

Z = 92Density = 19.1 g/cm3

TungstenZ = 74

Density = 19.3 g/cm3

TinZ = 50

Density = 5.8 g/cm3

IronZ = 26

Density = 7.9 g/cm3

Outline

Muon Tomography

Cubic-foot MTS with GEMs

Experimental Results

Future Work

6mm Al shielding

Simple Scattering Density (Degrees / cm3)

Uranium Tungsten Lead Tin Iron

157.8 115.3 101.0 68.9 61.3

Material Discrimination: Result

-55 mm < z < -15 mmMin. # of muon per voxel = 2

Outline

Muon Tomography

Cubic-foot MTS with GEMs

Experimental Results

Future Work

Lead Tungsten

IronTinUranium

155,104 Reconstructed Tracks

Voxel Size: 2 x 2 x 40 mm3

Material Discrimination: ResultXZ Slices

YZ Slices

Sn

+X

+YFe

Fe

U

U

Sn

Sn Pb W

WPb

Pb W

Fe

-70 mm < Y < -30 mm -20 mm < Y < 20 mm 30 mm < Y < 70 mm

30 mm < X < 70 mm-20 mm < X < 20 mm-70 mm < X < -30 mm

155,104 Reconstructed Tracks

Uranium with Brass Shielding

The shielded uranium block can clearly be seen in the reconstruction

Outline

Muon Tomography

Cubic-foot MTS with GEMs

Experimental Results

Future Work

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

Experimental Results

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.

Backup Slides

0 mm 2 mm 4 mm

6 mm 8 mm

Image Resolution Study: Imaging a gap separating W and Pb blocks

115,834 muons 94,719 muons 111,036 muons

107,506 muons 121,634 muons

0 mm 2 mm 4 mm

6 mm 8 mm

Scattering Density (deg/cm3)

Statistically significant signal with 8mm spacing Analysis Region