1XIXNPDC07092005G.Gorini ANCIENT CHARM A new project for neutron-based 3D imaging with applications...
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Transcript of 1XIXNPDC07092005G.Gorini ANCIENT CHARM A new project for neutron-based 3D imaging with applications...
XIXNPDC07092005 G.Gorini 1
ANCIENT CHARMA new project for neutron-based 3D imaging
with applications to cultural heritage research
G. Gorinion behalf of the Ancient Charm collaboration
XIXNPDC07092005 G.Gorini 2
Outline
ANCIENT CHARM
State of the art
Project objectives and plans
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ANCIENT CHARM
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ANCIENT CHARM
Analysis by Neutron resonant Capture Imaging and other Emerging Neutron Techniques: new
Cultural Heritage and Archaeological Research Methods
EU funded ADVENTURE project under the New and Emerging Science and Technology (NEST) programme of FP6. Expected start date: 01/2006. Duration: 36 months
XIXNPDC07092005 G.Gorini 5
Aim of ANCIENT CHARM
“To provide a new, comprehensive neutron-based imaging approach,
which will be applied here for the 3D imaging
of elemental and phase composition
of objects selected as a result of a broad scope archaeological research.”
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The ANCIENT CHARM Collaboration
A mix of expertise in neutron instrumentation and archaeology
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Available neutron sources
NIPS, Budapest (reactor)PGAA in regular use @ 107 n/cm2sRecently awarded a national grant to renew instrumentation.Expected increase of the neutron flux: factor or 5.
FRM-II, Garching (reactor)NT+PGAA beamline available in 2007 @ 109 n/cm2
GELINA, Geel (150 MeV LINAC, pulsed)NRCA in regular use
ISIS, Chilton (800 MeV p beam, pulsed)ND systems in regular use. Provides highest flux of epithermal neutrons.
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PGA beam line at the new research reactor FRM-II, Garching, Germany
Experimental hallNeutron guide hall
The new PGA and cold neutron tomography
station
Neutron flux ~ 1.5 – 6 109 cm-2 s-1
Initial beam size = 5 cm x 11.5 cm
Available in 2007
FRM-II
20 MW reactor
2.03.2004 First time critical
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The ISIS Facility
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Neutrons and Cultural Heritage Research
A large variety of chemical, physical and microstructural techniques
are employed to characterize objects of cultural significance.
Most of these methods are invasive.
Probes like X-rays and charged particles have limited penetration.
Neutrons penetrate thick layers depending on their energy. Use neutrons for quantitative, non-invasive analysis in bulk.
Neutron-based techniques: a recent development (exception: INAA).
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(I)NAA
PGAA
NRCA
T1/2
E
Resonances
Neu
tron
Ene
rgy
Cross section
E
Neutron Capture
XA *1A X+ ++ X1An +
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Neutrons-based techniques
Neutron Radiography/Tomography
(widespread)- similar to CT-3D images
Neutron Diffraction
(widespread)-mainly structural analysis-2D
Prompt Gamma Activation Analysis
(a few places)-elemental analysis-0D
Neutron Resonant Capture Analysis
(GELINA)-elemental analysis-0D
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STATE OF THE ART
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Cold Neutron Tomography
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Cold Neutron TomographyCold Neutron Tomography
Radiationsource
Sample
Radiograph
Measurement Analysis : Back-projection
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xyz translation rotation table
Detection system
Table
Sample
Beam
Pb + 6LiF
Lead glass
CCD
Mirror
420 m-thick ZnS(Ag) / 6LiF with Al backing
100 m-thick ZnS(Ag) / 6LiF
Conversion screen
Field of view : 2.7 mm x 3.4 mm
Image size : 640 x 512
Effective pixel size = 54 m
Typical exposure time ~ 2 s
Binning 2x2
12 bit CCD SensiCam camera
Pixel size : 6.7 6.7 m2
Number of pixels : 1280 1024
Readout Time : 8 fps
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Quality-control of pyrotechnic cutters used in space programs (Ariane)
Application in Aerospace Industry
Computer assisted inspection
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PSI:PSI:Kumakhov capillary-based neutron lens:Kumakhov capillary-based neutron lens:entrance height: 50mmentrance height: 50mmentrance width: 20mmentrance width: 20mmlength: 155mmlength: 155mmfocal distance: 150mmfocal distance: 150mmfocus at FWHM: 0.7mmfocus at FWHM: 0.7mmmax. gain on the spot: 16max. gain on the spot: 16
beam dimensionsbeam dimensions
FRM II:FRM II:Polycapillary bending Polycapillary bending and focusing lens:and focusing lens:entrance height: 45mmentrance height: 45mmentrance width: 50mmentrance width: 50mmlength: 190mmlength: 190mmfocal distance: ~95mmfocal distance: ~95mmfocus:focus: ~0.65mm ~0.65mmgain on the spot:~20gain on the spot:~20new spot: 20mm bellow the incoming beamnew spot: 20mm bellow the incoming beam
Neutron focusing lensNeutron focusing lens
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Neutron Diffraction
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GEM
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ENGIN-X
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The ENGIN-X transmission detector
100 element transmission detector for residual stress
measurements
Efficiency 85% at 1Å
Pixel array 10 x 10
Pixel size 2 mm x 2 mm on 2.5 mm pitch
Count rate 106 per PMT ie or 64 mm2
GS20 Glass scintillator pixels
Fibre light guides
Hamamatsu 16 channel position sensitive PMTs
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Neutron transmission and Bragg edges
Pulsed neutronsource
5000 10000 15000 20000
0
10000
20000
30000
40000
Counts
TOF (sec)
Incidentspectrum
Sample (, A)
5000 10000 15000 20000
0
10000
20000
30000
40000
50000
Counts
TOF (sec)
Transmittedspectrum
( ) ( )⎟⎠
⎞⎜⎝
⎛−= λσλλ xA
II exp)( 0
x
( )( ) ( )λσλλ
nxI
I=⎟⎟
⎠
⎞⎜⎜⎝
⎛−
0
ln
Pixelated detector ( )
( )λλ
0I
ITr =
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Strain around a cold expanded hole
Neutrons
Straindirection
x
y
z
Strain values
350-400 ε300-350 ε
400-450 ε450-500 ε
Above 500 ε
250-300 ε200-250 ε150-200 ε100-150 ε100-150 ε50-100 ε
0-50 ε-50 -0 ε
-100 -50 εBelow -100 ε
y (mm)
x (mm)5 10 15
-20
-15
-10
-5
0
0
5
10
15
20
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Prompt Gamma Activation Analysis
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The NIPS experimental stationThe NIPS experimental station
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1E-2
1E-1
1E+0
1E+1
1E+2
1E+3
1E+4
1E+5
H Li B C N F Na Mg A l Si P S Cl K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Rb Sr Y Zr Nb
Sensitivity (cps/g)
Sensitivities at the PGAA-NIPS facility
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Pilot experiment for imaging
Neutron beam 1 mm
0.10
1.00
10.00
100.00
0 100 200 300 400
deg
cps
184
278
343
HPGedetector
SiO2
Cu
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Neutron ResonantCapture Analysis
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NRCA on a prehistoric bronze axe
0
5000
1 104
1.5 104
2 104
2.5 104
1 10 100 1000
AXE5/mar/R1/adc1&2&tot;080403(N/eV)/flux
E(eV)
AXE 5A.U.
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Comparison: NRCA vs. PGAA
• PGAA
σc thermal capture cross section
branching
ε detection efficiency a atomic abundance
• NRCA
A,r resonance area
1/Er flux shape
rr,r E
1AaS =
co ak σε=
)eVb(E
g10097.4A
r
n6r, Γ
ΓΓ=
XIXNPDC07092005 G.Gorini 32
PGAA <----> NRCAPGAA (at Budapest) and NRCA (GELINA)Accuracy for Cu in a bronze artefact about 1%
ko and Sr relative to Cu
-4 -2 0 2 4
-4
-2
0
2
4
Z ≤ 20 21 ≤ Z ≤ 69 70 ≤ Z ≤ 83
( ln S
r( ) / i S
r( ) )Cu
ln( k0(i) / k0(Cu) )
PGAA best for light elements– H, S, P, and K
NRCA best for heavy elements– As, Ag, Sb, Sn, Au
and Pb
XIXNPDC07092005 G.Gorini 33
0
1 105
2 105
Ag
0
200
400
600
100 200 300 400 500Time of flight ( )s
Au
Pilot NRCA tests on ISIS
Small YAP detectorThreshold: ≈0.6 MeV
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PROJECT OBJECTIVESAND PLANS
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Work packages
Cultural heritage foundations of neutron-based imaging
From PGAA to PGAI/NT
From NRCA to NRCI/NRT
High neutron flux NRCI/NRT
Model simulations of new hardware
Analysis and simulation tools for NRCI/NRT
Integration of imaging methods
Neutron imaging of cultural heritage samples
XIXNPDC07092005 G.Gorini 36
From NRCA to NRCI/NRT
Spatially resolved information: combination of
-tight neutron beam collimation,
-multiple positioning of the sample,
-simultaneous measurement of neutron resonances with different strengths.
=> “Neutron Resonant Capture Imaging” combined with
“Neutron Resonance Transmission” (NRCI/NRT):
•Transmission and measurements simultaneously.
•Use YAP crystals for detection.
•Produce images using a few resonances.
XIXNPDC07092005 G.Gorini 37
400 mm
400 mm
Boron collimator
YAP Crystal detectors
Transmission detectorXYZ- stage
Li (or B) cladding
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Transmission vs. measurements
Transmission
• Requires good angular collimation and a large beam.
• Produce 2D images directly (like neutron tomography)
• Need to scan in 1 dimension ()
• Contrast is produced using the depth of the resonant absorption.
• Neutron and background not an issue.
• Has problems with very diluted and very concentrated systems.
measurements
• Requires a small beam.
• Produces cord-integrated 0-D points.
• Need to scan in 3 D (YZ)
• Contrast is produced by the intensity of the peak.
• background is an issue.
• Has problems at low concentrations if background is high.
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A 2D NRT detector
• Experience on existing detectors at ISIS
1. Engin-X 2D transmission monitor: 100 pixels, 2x2x2 mm3 for thermal -cold neutrons
2. PEARL NRC detector, single pixel , 7X7X25 mm3
• Issues Pixels must be deep for efficiency. Alignment?
Require large beam with low angular divergence and short S-D distance (similar to radiography). Currently about 10 mrad.
A 2D NRT detector with 1-2mm pixel resolution should be feasible
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Conclusions:
in 3 years.
Meanwhile...
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