Status of Muon Tomography with SRS at FITand some early beam results with SRS

Michael Staib, Marcus HohlmannFlorida Institute of Technology

Kondo GnanvoUniversity of Virginia

RD51 Mini Week WG5 June 13, 2012

Muon Tomography for Homeland Security

Photo: Sci. Am., 04/2008

Radiati

onRadiationDetectors But it is easy to avoid

passive detection of nuclear threat material that is looking for radiological

signatures.

Just add shielding!

There may be a solution...

• More than 23 million cargo containers and 93 million privately-owned vehicles were processed by U.S. Customs and Border Protection in the last year.

• New requirement: 100% scanning of all U.S.-bound containers using non-intrusive imaging equipment and radiation detection equipment to search for a nuclear threat.

Muon Tomography Concept

μμ

Fe U

LargeScattering

Small Scattering

μIron

Small Scattering

Uraniumμ

LargeScattering

μμIncoming muons (from natural cosmic rays)

Note: Angles Exaggerated!

)]/ln(038.01[MeV6.13

00

0 XxX

x

cp

Tracking detectors

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

𝑋0 = 716.4 g cm-2 ∙AZሺZ + 1ሻln (287 ξ𝑍Τ )

Muon Tomography with Drift Tubes

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 Corp.: Multi-Mode Passive Detection System, MMPDSTM

INFN

CMSCMS

Decision Sciences prototype using drift tubes large enough to scan a vehicle.

C. Milner, et al., “Non-Invasive Imaging of Reactor Cores Using Cosmic Ray Muons”, SMU Physics Department Seminar, March 2012.

Compact Cubic-Foot Muon Tomography Station with GEMs

Plastic Scintillator

Triple-GEM Detector

~ 1 ft3

Discriminator and coincidence card

Two of the GEM detectors used were assembled at Florida Tech

SRS for Muon Tomography

Current station configuration with 8 detectors:

•96 APV Hybrid (48 M/S pairs)•6 ADC/FEC cards•2 Gigabit network switches

Six 25 ns frames of data recorded for each APV per trigger yields event size of ~200kb @ 30 Hz.

DATE for data acquisition.

AMORE for data decoding, event monitoring and data analysis.

6

Tomographic POCA Reconstructions of Target Scenarios

Tomographic Reconstructions Presented

•Material discrimination performance using five targets.

•Depleted uranium shielded with medium-Z shielding.

POCA Reconstruction Limitations

•Assumes multiple scattering is well approximated by a single point.

•Not valid in the case of large amounts of material! Statistical methods must be employed.

•Does not take into account the momentum of the muon.

𝜃 = cos−1ቆ𝑨ሬሬԦ ∙𝑩ሬሬԦห𝑨ሬሬԦหห𝑩ሬሬԦหቇ

The POCA can be found using the fact that the shortest line segment joining the incoming and outgoing vectors will be orthogonal to both.

Reconstruction AlgorithmPoint of Closest Approach

(POCA)

Object

Five-Target Scenario

LeadZ = 82ρ = 11.4 g/cm3

X0 = 0.56 cm Depleted UraniumZ = 92ρ = 19.0 g/cm3

X0 = 0.32 cm

TungstenZ = 74ρ = 19.3 g/cm3

X0 = 0.35 cm

TinZ = 50ρ = 7.3 g/cm3

X0 = 1.21 cm

IronZ = 26ρ = 7.9 g/cm3

X0 = 1.76 cm

6mm Al shielding

Five 75 cm3 targets were placed inside the imaging volume at three different Z locations.

Five-Target Scenario

Single cluster track selection155,104 reconstructed tracksNNP cut = 52 mm x 2 mm x 40 mm voxels

Pb W

FeSn

U

Results are good!

Can discriminate between high/low Z as well as high/medium Z.

Tungsten vs. Uranium not so easy...

Results match 1/X0 dependence quite well

Five-Target Scenario

XZ 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

Single cluster track selection155,104 reconstructed tracksNNP cut = 52 mm x 2 mm x 40 mm voxels

Stacked Five-Target Scenario

• Stacks of each of the five materials were imaged using the MTS

• Targets vary in size from 27 cm3 to 150 cm3

• 175,022 tracks reconstructed using single cluster selection

Stacked Five-Target Scenario

Single cluster track selection175,022 reconstructed tracksNNP cut = 62 mm x 2 mm x 40 mm voxels

Uranium Tungsten Lead Tin Iron

152.8 140.6 112.2 72.9 64.1

Simple Scattering Density [deg/cm3]

We are able to discriminate between the low/medium/high-Z materials!

40 mm slice

40 mm XY slice descending in Z by 5 mm per frame

Stacked Five-Target Scenario

WPb

WFeU

USn Fe

Sn Pb

Single cluster track selection175,022 reconstructed tracksNNP cut = 62 mm x 2 mm x 40 mm voxels

XZ Slices

YZ Slices

Depleted Uranium with Bronze Shielding

Mixed track selection187,731 reconstructed tracks2 mm x 2 mm x 40 mm voxels

40 mm XY slice with NNP cut increasing by 1 per frame

The shielded uranium can be discriminated from the

bronze shielding using POCA reconstruction

Depleted Uranium with Bronze Shielding

Mixed track selection187,731 reconstructed tracks2 mm x 2 mm x 40 mm voxels

XZ slice with NNP cut increasing by 1 per frame

The shielded uranium can be discriminated from the

bronze shielding using POCA reconstruction

YZ slice with NNP cut increasing by 1 per frame

What about the side views?

Status of Muon Tomography• We have shown the ability of the MTS using GEMs to discriminate

between materials of similar volume with different Z, even as shielding.

• SRS is working very well!

• Still unresolved issue of network switch requirements and exact cause of missing triggers.

• Will try to implement the zero suppression firmware soon and work on clock synchronization.

• Plans to possibly scale to ~1 m3 active volume in the future.

• Many thanks to Sorin, Hans, Filippo and Leszek for their help throughout the process.

CA

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k2 mm 2 mm

Beam Test 2012Zig-Zag (Chevron) strips to reduce readout channels while maintaining spatial resolution

Preliminary Results

Zero Suppression

Raw Data Pedestal Subtracted Data

Zero Suppressed (5σ RMS) Data Time Evolution of Zero Suppressed Signal

Floating channels(not connected)

48 Zig-ZagRO Strips

Strip Number

Mean = 2.7 StripsMean = 1.1 Clusters

Pedestal Noise Cluster Charge Distribution

Cluster Size Distribution Cluster Multiplicity

Beam Test 2012New RD51 tracker with resistive strip MicroMegas and SRS APV readout

Readout Strips parallel to resistive strips

Readout perpendicular to resistive strips

Thanks!Questions?

Backup Slides

Post-Processing to Remove Noise

• A “number of neighboring POCA ” (NNP) cut is made in order to improve the quality of the reconstructions.

• There is also a cut removing all voxels with mean scattering angle less than 2 degrees.

V

• Add up the total number of POCA points in the blue voxels surrounding voxel V, this is the NNP.

• If the NNP is less than a threshold, remove the contents of voxel V.

• Repeat for all voxels in the histogram.

Method Results