Presentation on theme: "1XIXNPDC07092005G.Gorini ANCIENT CHARM A new project for neutron-based 3D imaging with applications to cultural heritage research G. Gorini on behalf."— Presentation transcript:
4XIXNPDC07092005G.Gorini 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
5XIXNPDC07092005G.Gorini 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.
6XIXNPDC07092005G.Gorini The ANCIENT CHARM Collaboration A mix of expertise in neutron instrumentation and archaeology
7XIXNPDC07092005G.Gorini Available neutron sources NIPS, Budapest (reactor) PGAA in regular use @ 10 7 n/cm 2 s Recently 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 @ 10 9 n/cm 2 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.
8XIXNPDC07092005G.Gorini PGA beam line at the new research reactor FRM-II, Garching, Germany Experimental hall Neutron guide hall The new PGA and cold neutron tomography station Neutron flux ~ 1.5 – 6 10 9 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
10XIXNPDC07092005G.Gorini 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).
11XIXNPDC07092005G.Gorini (I)NAA PGAA NRCA T 1/2 E Resonances Neutron Energy Cross section E Neutron Capture
12XIXNPDC07092005G.Gorini 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
16XIXNPDC07092005G.Gorini xyz translation rotation table Detection system Table Sample Beam Pb + 6 LiF Lead glass CCD Mirror 420 m-thick ZnS(Ag) / 6 LiF with Al backing 100 m-thick ZnS(Ag) / 6 LiF 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 m 2 Number of pixels : 1280 1024 Readout Time : 8 fps
17XIXNPDC07092005G.Gorini Quality-control of pyrotechnic cutters used in space programs (Ariane) Application in Aerospace Industry Computer assisted inspection
18XIXNPDC07092005G.Gorini PSI: Kumakhov capillary-based neutron lens: entrance height: 50mm entrance width: 20mm length: 155mm focal distance: 150mm focus at FWHM: 0.7mm max. gain on the spot: 16 beam dimensions FRM II: Polycapillary bending and focusing lens: entrance height: 45mm entrance width: 50mm length: 190mm focal distance: ~95mm focus: ~0.65mm gain on the spot:~20 new spot: 20mm bellow the incoming beam Neutron focusing lens
22XIXNPDC07092005G.Gorini The ENGIN-X transmission detector 100 element transmission detector for residual stress measurements Efficiency 85% at 1 Å Pixel array 10 x 10 Pixel size 2 mm x 2 mm on 2.5 mm pitch Count rate 10 6 per PMT ie or 64 mm 2 GS20 Glass scintillator pixels Fibre light guides Hamamatsu 16 channel position sensitive PMTs
23XIXNPDC07092005G.Gorini Neutron transmission and Bragg edges Pulsed neutron source Incident spectrum Sample (, A) Transmitted spectrum x Pixelated detector
24XIXNPDC07092005G.Gorini Strain around a cold expanded hole
30XIXNPDC07092005G.Gorini NRCA on a prehistoric bronze axe
31XIXNPDC07092005G.Gorini Comparison: NRCA vs. PGAA PGAA c thermal capture cross section branching detection efficiency a atomic abundance NRCA A,r resonance area 1/E r flux shape
32XIXNPDC07092005G.Gorini PGAA NRCA PGAA (at Budapest) and NRCA (GELINA) Accuracy for Cu in a bronze artefact about 1% k o and S r relative to Cu PGAA best for light elements –H, S, P, and K NRCA best for heavy elements –As, Ag, Sb, Sn, Au and Pb
33XIXNPDC07092005G.Gorini Pilot NRCA tests on ISIS Small YAP detector Threshold: 0.6 MeV
34XIXNPDC07092005G.Gorini PROJECT OBJECTIVES AND PLANS
36XIXNPDC07092005G.Gorini 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.
37XIXNPDC07092005G.Gorini 400 mm Boron collimator YAP Crystal detectors Transmission detector XYZ- stage Li (or B) cladding
38XIXNPDC07092005G.Gorini 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.
39XIXNPDC07092005G.Gorini A 2D NRT detector Experience on existing detectors at ISIS 1.Engin-X 2D transmission monitor: 100 pixels, 2x2x2 mm 3 for thermal - cold neutrons 2.PEARL NRC detector, single pixel, 7X7X25 mm 3 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
40XIXNPDC07092005G.Gorini Conclusions: in 3 years. Meanwhile...
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