High-resolution high-contrast X-ray and neutron imaging with hybrid pixel detectors F. Krejci , J. Jakubek, J. Zemlicka, J. Dudak, M. Jakubek, M. Platkevic, P. Soukup, D. Turecek, D. Vavrik, S. Pospisil Institute of Experimental and Applied Physics Czech Technical University in Prague Work carried out within the Medipix Collaboration. CRISP Workshop on Imaging with Neutrons Grenoble, 17th March 2014 Frantisek Krejci 1
Outline Institute of Experimental and Applied Physics Czech Technical University in Prague Hybrid pixel semiconductor detectors (HPSD) Application in high-resolution high-contrast X-ray radiography • Biology, biomedical research • Industrial application (non-destructive testing) Neutron radiography with HPSD • Current challenges • Application possibilities Conclusions Grenoble, 17th March 2014 Frantisek Krejci 2
X-ray transmission radiography (absorption based) Institute of Experimental and Applied Physics Czech Technical University in Prague Wilhelm Conrad Roentgen showed that bones could be visualized by X- raying his wife's hand in 1895 Sample X-ray beam Shadow attenuating Radiogram projected on an radiation imager Huge progress in radiogram quality is based on X-ray sources (synchrotrons, micro-focus and nano-focus X-ray o generators) X-ray detector (especially semiconductor hybrid pixel technology) o Grenoble, 17th March 2014 Frantisek Krejci 3
Detectors for radiation imaging Institute of Experimental and Applied Physics Czech Technical University in Prague Single particle Charge integrating Film emulsions (counting) pixel devices change of chemical or detectors physical properties after Ionizing radiation creates Ionizing radiation creates interaction with charge which is collected charge which is radiation. Needs special and integrated in pixels compared with threshold treatment (developing (CCDs, CMOS sensors, and registered digitally in process, scanning, …). Flat panels, …) pixels + + + Good spatial resolution Very high resolution High spatial resolution High read-out speed Low noise Low price No noise, no dark current Cheap Unlimited dynamic range - - - Nonlinear response Dark current Limited dynamic range Noise ? Needs processing Limited dynamic range Grenoble, 17th March 2014 Frantisek Krejci 4
Particle counting pixel detectors Institute of Experimental and Applied Physics Czech Technical University in Prague Pilatus - PSI Bias Voltage 60 x 97 pixels Pitch of 172 um Counter: 20 bits (Si) Single threshold + Module 16 chips Large area - tilling Medipix2 – CERN 256 x 256 pixels Threshold Amplifier Level(s) Pitch of 55 um Two thresholds Module 4 chips Compa- rator(s) Timepix - CERN Time stamp Counter: Particle count ToT mode 000 001 Pixel Pixel Pixel electronics electronics electronics 55 µm Grenoble, 17th March 2014 Frantisek Krejci 5
High contrast X-ray imaging: Example: Living mouse Institute of Experimental and Applied Physics Czech Technical University in Prague Surrounding soft tissue Very light parts: hair Hard structures: skull Softer structures: muscles Even softer structures Single photon counting Example 1 : device can count unlimited number of photons, noise in images is given just by poissonian statistics: X-ray transmission => Unlimited number of gray levels in images depending just on the beam intensity and Single image of mouse exposure time. head => Almost unlimited contrast (dose 0.9 mGy) Mouse head – different scaling of same data Grenoble, 17th March 2014 Frantisek Krejci 6
X-ray radiography: Mouse kidney X-ray radiography Institute of Experimental and Applied Physics Czech Technical University in Prague Needle holding the sample Grenoble, 17th March 2014 Frantisek Krejci 7
Setup for high-resolution high-contrast X-ray radiography and CT Institute of Experimental and Applied Physics Czech Technical University in Prague Imaging Object X-ray detector Point-like X-ray source Enlarged projection Grenoble, 17th March 2014 Frantisek Krejci 8
High-resolution high-contrast X-ray radiography with hybrid pixel detectors Institute of Experimental and Applied Physics Czech Technical University in Prague X-rays Optical light Digital particle integration (counting) • Virtually unlimited dynamic range and • exposure time 2 mm Detected count obeys poissonian • distribution -> SNR dependent just on the number of detected particles Many new possibilities in radiation imaging • So far to small imaging area • (typically 14 x 14 mm 2 ) for many applications V. Sykora, J. Zemlicka, F. Krejci, J. Jakubek, Science 339 (2013). Grenoble, 17th March 2014 Frantisek Krejci 9
Large area pixel detector Goals & Challenges Institute of Experimental and Applied Physics Czech Technical University in Prague Size of single chip in 130 nm technology is limited to about 2 x 2 cm 2 Tiling is the only option Requirements Standard Timepix assembly with edgeless sensor used (14 x 14 mm 2 ) 100% area coverage ( never realized successfully before ) Mechanical precision much better than 1 pixel (ideally even better ) At least 10 x 10 chips, (14.4 x 14.4 cm 2 , 6.5 Megapixel camera) Readout architecture Powering Temperature stabilization (cooling) Software Use individual TPX assemblies with edgeless sensors instead of large common sensor shared by many TPX chips => possibility to select good chips => high yield Grenoble, 17th March 2014 Frantisek Krejci 10
WidePIX 6.5 megapixels The largest pixel detector with full area sensitivity Institute of Experimental and Applied Physics Czech Technical University in Prague camera consists of array of 10 x 10 of hybrid single • quantum counting detector Timepix developed by Medipix collaboration in CERN. The technology allowing coverage of large area is • based on application of edgeless silicon sensors developed in VTT Finland and fabricated by ADVACAM Oy. The whole WidePIX device was developed by IEAP • CTU in Prague. 200 µm Sensor 2 ROC2 Sensor 1 Gap ROC1 Grenoble, 17th March 2014 Frantisek Krejci 11
Demonstration of continuous sensitive area: X-ray radiography of light bulbs Institute of Experimental and Applied Physics Czech Technical University in Prague Convectional X-ray tube used : 50 µm spot • 70 keV • 500 µA • exposure time 180s • contact geometry • One single chip (tile) is marked by red square No apparent image distortion Sensitive area 14.4 x 14.4 cm 2 Grenoble, 17th March 2014 Frantisek Krejci 12
Demonstration of continuous sensitive area and high sensitivity: X-ray radiography of Lily Institute of Experimental and Applied Physics Czech Technical University in Prague Convectional X-ray tube used : 50 µm spot • 70 keV • 500 µA • exposure time 180s • contact geometry • No apparent image distortion Sensitive area 14.4 x 14.4 cm 2 Sensitivity for soft-tissue imaging Grenoble, 17th March 2014 Frantisek Krejci 13
Application in biology: Ground beetle Institute of Experimental and Applied Physics Czech Technical University in Prague Micro-focus X-ray tube used : 5 µm spot, • 90 keV, 70 µA • Magnification 5 x (resolution 11 µm) • Micrometer level spatial resolution for few cm large objects Grenoble, 17th March 2014 Frantisek Krejci 14
Application in biology: Cockroach with a parasite Institute of Experimental and Applied Physics Czech Technical University in Prague Grenoble, 17th March 2014 Frantisek Krejci 15
Application in biomedical research: Small animal imaging Institute of Experimental and Applied Physics Czech Technical University in Prague Grenoble, 17th March 2014 Frantisek Krejci 16
WidePIX - Sample images: Smoking kills Institute of Experimental and Applied Physics Czech Technical University in Prague Grenoble, 17th March 2014 Frantisek Krejci 17
WidePIX Composite materials imaging Institute of Experimental and Applied Physics Czech Technical University in Prague FP7 projetc: Quantitative Inspection of Complex Composite Aeronautic Parts Using Advanced X-ray Techniques) Paper – epoxy composite (Boeing, motor cover) Grenoble, 17th March 2014 Frantisek Krejci 18
WidePIX Composite imaging Paper – epoxy composite: Zoomed to 40 x 20 mm Institute of Experimental and Applied Physics Czech Technical University in Prague Grenoble, 17th March 2014 Frantisek Krejci 19
Sandwich structures with metal core – loss of the stability Institute of Experimental and Applied Physics Czech Technical University in Prague Deformed walls of hexagonal core Grenoble, 17th March 2014 Frantisek Krejci 20
Institute of Experimental and Applied Physics Czech Technical University in Prague Neutron imaging with hybrid pixel semiconductor detectors Grenoble, 17th March 2014 Frantisek Krejci 21
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