pixel detectors F. Krejci , J. Jakubek, J. Zemlicka, J. Dudak, M. - - PowerPoint PPT Presentation

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pixel detectors F. Krejci , J. Jakubek, J. Zemlicka, J. Dudak, M. - - PowerPoint PPT Presentation

Sep 02, 2023 99 likes •458 views

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

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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.

Grenoble, 17th March 2014 1

CRISP Workshop on Imaging with Neutrons

Frantisek Krejci

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Institute of Experimental and Applied Physics Czech Technical University in Prague

Outline

Grenoble, 17th March 2014 2

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

Frantisek Krejci

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Institute of Experimental and Applied Physics Czech Technical University in Prague

X-ray transmission radiography

(absorption based)

Grenoble, 17th March 2014 3

Sample attenuating radiation Shadow projected on an imager

Radiogram

X-ray beam

Wilhelm Conrad Roentgen showed that bones could be visualized by X- raying his wife's hand in 1895

Huge progress in radiogram quality is based on

  • X-ray sources (synchrotrons, micro-focus and nano-focus X-ray

generators)

  • X-ray detector (especially semiconductor hybrid pixel technology)

Frantisek Krejci

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Institute of Experimental and Applied Physics Czech Technical University in Prague

Detectors for radiation imaging

Grenoble, 17th March 2014

Film emulsions

change of chemical or physical properties after interaction with

  • radiation. Needs special

treatment (developing process, scanning, …). Very high resolution Low noise Cheap Nonlinear response Limited dynamic range Needs processing

Charge integrating devices

Ionizing radiation creates charge which is collected and integrated in pixels (CCDs, CMOS sensors, Flat panels, …) High spatial resolution Low price Dark current Noise Limited dynamic range

+

  • +
  • Single particle

(counting) pixel detectors

Ionizing radiation creates charge which is compared with threshold and registered digitally in pixels Good spatial resolution High read-out speed

No noise, no dark current Unlimited dynamic range

?

+

  • 4

Frantisek Krejci

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Institute of Experimental and Applied Physics Czech Technical University in Prague

Particle counting pixel detectors

Grenoble, 17th March 2014

Pilatus - PSI

60 x 97 pixels

Pitch of 172 um

Counter: 20 bits

Single threshold

Module 16 chips

Large area - tilling

Medipix2 – CERN

256 x 256 pixels

Pitch of 55 um

Two thresholds

Module 4 chips

Timepix - CERN

Time stamp

ToT mode

(Si)

Amplifier Compa- rator(s)

Counter: Particle count

000 001

Pixel electronics Pixel electronics Pixel electronics +

Bias Voltage Threshold Level(s) 5 Frantisek Krejci

55 µm

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Institute of Experimental and Applied Physics Czech Technical University in Prague

High contrast X-ray imaging:

Example: Living mouse

Grenoble, 17th March 2014

Single photon counting device can count unlimited number of photons, noise in images is given just by poissonian statistics:

=> Unlimited number of gray levels in images depending just on the beam intensity and exposure time. => Almost unlimited contrast

Mouse head – different scaling of same data

Hard structures: skull

Softer structures: muscles Even softer structures Surrounding soft tissue Very light parts: hair

Example 1:

X-ray transmission Single image of mouse head (dose 0.9 mGy)

6 Frantisek Krejci

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Institute of Experimental and Applied Physics Czech Technical University in Prague

X-ray radiography:

Mouse kidney X-ray radiography

Grenoble, 17th March 2014

Needle holding the sample

7 Frantisek Krejci

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Institute of Experimental and Applied Physics Czech Technical University in Prague

Setup for high-resolution high-contrast X-ray radiography and CT

Grenoble, 17th March 2014

Point-like X-ray source Imaging X-ray detector Object Enlarged projection

8 Frantisek Krejci

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Institute of Experimental and Applied Physics Czech Technical University in Prague

High-resolution high-contrast X-ray radiography with hybrid pixel detectors

  • Digital particle integration (counting)
  • Virtually unlimited dynamic range and

exposure time

  • 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 mm2) for many applications

  • V. Sykora, J. Zemlicka, F. Krejci, J. Jakubek, Science 339 (2013).

X-rays Optical light

2 mm

Grenoble, 17th March 2014 9 Frantisek Krejci

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Institute of Experimental and Applied Physics Czech Technical University in Prague

Large area pixel detector

Goals & Challenges

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Size of single chip in 130 nm technology is limited to about 2 x 2 cm2

 Tiling is the only option

Requirements

Standard Timepix assembly with edgeless sensor used (14 x 14 mm2)

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 cm2, 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

Frantisek Krejci

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Institute of Experimental and Applied Physics Czech Technical University in Prague

WidePIX 6.5 megapixels

The largest pixel detector with full area sensitivity

Grenoble, 17th March 2014

  • 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 1 ROC1 Sensor 2 ROC2

Gap

11 Frantisek Krejci

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Institute of Experimental and Applied Physics Czech Technical University in Prague

Demonstration of continuous sensitive area:

X-ray radiography of light bulbs

Grenoble, 17th March 2014 12 Frantisek Krejci

 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 cm2

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Institute of Experimental and Applied Physics Czech Technical University in Prague

Demonstration of continuous sensitive area and high sensitivity:

X-ray radiography of Lily

Grenoble, 17th March 2014 13 Frantisek Krejci

 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 cm2  Sensitivity for soft-tissue imaging

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Institute of Experimental and Applied Physics Czech Technical University in Prague

Application in biology:

Ground beetle

Grenoble, 17th March 2014 14 Frantisek Krejci

 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

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Institute of Experimental and Applied Physics Czech Technical University in Prague

Application in biology:

Cockroach with a parasite

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Institute of Experimental and Applied Physics Czech Technical University in Prague

Application in biomedical research: Small animal imaging

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Institute of Experimental and Applied Physics Czech Technical University in Prague

WidePIX - Sample images:

Smoking kills

Grenoble, 17th March 2014 17 Frantisek Krejci

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Institute of Experimental and Applied Physics Czech Technical University in Prague

WidePIX

Composite materials imaging

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Paper–epoxy composite (Boeing, motor cover)

Frantisek Krejci

FP7 projetc: Quantitative Inspection of Complex Composite Aeronautic Parts Using Advanced X-ray Techniques)

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Institute of Experimental and Applied Physics Czech Technical University in Prague

WidePIX Composite imaging

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Paper–epoxy composite: Zoomed to 40 x 20 mm

Frantisek Krejci

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Institute of Experimental and Applied Physics Czech Technical University in Prague

Sandwich structures with metal core – loss of the stability

Grenoble, 17th March 2014

Deformed walls

  • f hexagonal

core

20 Frantisek Krejci

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Institute of Experimental and Applied Physics Czech Technical University in Prague

Grenoble, 17th March 2014 21 Frantisek Krejci

Neutron imaging with hybrid pixel semiconductor detectors

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Institute of Experimental and Applied Physics Czech Technical University in Prague

Principle: Semiconductor pixel detector can barely detect slow neutrons directly.

 Conversion of thermal neutrons to detectable radiation in a suitable material is needed.

Placement of a converter:

  • n the sensor surface (coated detector),

inside of the sensor volume (stuffed detector), converter is a component of the sensing material. Converter materials: Cross section

6Li: 6Li + n  a (2.05 MeV) + 3H (2.72 MeV)

940 barns

10B: 10B + n  a (1.47 MeV) + 7Li (0.84 MeV) + g (0.48MeV)

(93.7%)

10B + n  a (1.78 MeV) + 7Li (1.01 MeV)

(6.3%) 3 840 barns

113Cd: 113Cd + n  114Cd + g (0.56MeV) + conversion electrons

26 000 barns

155Gd:

155Gd + n  156Gd + g (0.09, 0.20, 0.30 MeV) + conversion electrons

157Gd:

157Gd + n  158Gd + g (0.08, 0.18, 0.28 MeV) + conversion electrons ~60 000 barns

Adaptation of the pixel device for slow neutron detection

Grenoble, 17th March 2014

Neutron beam

back side contact grid

e n

22 Frantisek Krejci

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Institute of Experimental and Applied Physics Czech Technical University in Prague

Neutron micro-radiography

Wrist watch

Grenoble, 17th March 2014

Metallic cover was fixed on watch in time of measurement !

Exposition time = 500 seconds

Planar 6LiF converter on the Mexipix2 chip

23 Frantisek Krejci

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Institute of Experimental and Applied Physics Czech Technical University in Prague

Neutron micro-tomography

Grenoble, 17th March 2014

Blank cartridge Explosive filling clearly visible

Taken 100 projections 150 seconds each. Reconstruction using filtered back-projection algorithm.

24 Frantisek Krejci

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Institute of Experimental and Applied Physics Czech Technical University in Prague

Neutron microtomography

Grenoble, 17th March 2014

Lemo connector Golden contacts inside

Taken 100 projections 150 seconds each. Reconstruction using filtered back-projection algorithm.

25 Frantisek Krejci

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Institute of Experimental and Applied Physics Czech Technical University in Prague

New camera for neutron imaging:

WidePIX 4x5, 1.3 Mega pixels

Grenoble, 17th March 2014

Shown without neutron converter

26 Frantisek Krejci

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Institute of Experimental and Applied Physics Czech Technical University in Prague

Neutron radiography with novel large area detector (6 x 7.5 cm2)

Grenoble, 17th March 2014

6LiF deposited on the surface

First tests performed in ILL, CT2 beam line Low intensity beam -> long exposure

Exposure: 1000 s

27 Frantisek Krejci

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Institute of Experimental and Applied Physics Czech Technical University in Prague

6LiF convertor:

Spatial resolution

Grenoble, 17th March 2014

100mm 50mm =>Resolution ~ 65 mm Gd calibrator: Siemens star

Spatial resolution beyond this limit (for micrometer-size features) desired in many fields remains a challenge.

28 Frantisek Krejci

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Institute of Experimental and Applied Physics Czech Technical University in Prague

Tracking mode

Grenoble, 17th March 2014

Typical tracks recorded by the Timepix device in the TOT mode for different particle types produced by the neutron reactions: a) Electron dot tracks - low energy gammas or electrons b) Long tracks of electrons - high energy gammas. c) Heavy tracks created by products of neutron conversion a) b) c)

Si LiF n

T α

Every particle is recorded and processed as a standalone object – spatial resolution improvement, background suppression, ….

29 Frantisek Krejci

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Institute of Experimental and Applied Physics Czech Technical University in Prague

Heavy charged particles:

Sub-pixel resolution

Grenoble, 17th March 2014

Precision of particle position of interaction can be improved by cluster centroiding Cluster shape depends on detector bias voltage. For low bias Gaussian cluster shape => position can be found by fitting.

95 100 X 200 400 Energy [keV] 30 35 Y

2 detected clusters Cluster size can be >100

Ionizing particle Pixel cells

Ionizing particle can creates huge charge signal in several adjacent pixels forming cluster. Cluster volume depends on particle energy. Cluster morphology depends on particle type.

30 Frantisek Krejci

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Institute of Experimental and Applied Physics Czech Technical University in Prague

Experiment:

Spatial resolution (6LiF convertor)

Grenoble, 17th March 2014

Straight edge made of stainless steel (50 um thick) placed onto detector surface. Positions of all detected clusters evaluated with sub-pixel precision. A spatial resolution of 2.3 μm (sigma of the error function) was measured this

  • way. This result corresponds to 5.3 μm of FWHM of point spread function.

Ultra-cold neutron beam at ILL Grenoble used.

31 Frantisek Krejci

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Institute of Experimental and Applied Physics Czech Technical University in Prague

Novel fast-read out detector architecture

Grenoble, 17th March 2014 Frantisek Krejci 32

 Sensitive area 3 x 3 cm2  Frame rate 800 frames per second  Very effective

  • peration in the

event-by-event regime  Area scalability (le.g. long row detector)

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Institute of Experimental and Applied Physics Czech Technical University in Prague

Conclusions

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Noiseless single particle counting detectors provide excellent tool for radiation imaging High-contrast high-resolution (down to 1 µm) X-ray radiography in a table top setup is currently available With the large sensitive area detector increased application potential (biology, biomedicine, non-destructive testing) Adaptation of HPSD for neutron imaging is possible  opens ways to high quality neutron imaging

Frantisek Krejci

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Institute of Experimental and Applied Physics Czech Technical University in Prague

Grenoble, 17th March 2014 34

Thank you for your attention

Frantisek Krejci