IEAP CTU Prague 8 th December, 2004Tom Hol½ Neutron tomography with Medipix-2 Tom Hol½, Jan Jak¯bek, Stanislav Posp­il, Josef Uher

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IEAP CTU Prague 8 th December, 2004Tom Hol Neutron tomography with Medipix-2 Tom Hol, Jan Jakbek, Stanislav Pospil, Josef Uher Slide 2 Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP CTU Prague 8 th December, 2004Tom Hol Outline Tomography principles Filtered backprojection algorithm Adaptation of Medipix-2 for neutron detection Examples of micro-tomography reconstructions Comparison with Medipix-1 Conclusion and outlook Slide 3 Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP CTU Prague 8 th December, 2004Tom Hol Tomography measurement Medipix-2 detector Sample Step motor Slice of sample and its projection on detector Parallel neutron beam Slide 4 Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP CTU Prague 8 th December, 2004Tom Hol Neutron transmission Neutron beam intensity attenuation: a(x,y) attenuation coefficient function Sample attenuating the beam Projection on detector plane Reconstruction of a(x,y) Slide 5 Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP CTU Prague 8 th December, 2004Tom Hol Parallel projections Projection P (t) x y Object slice a(x,y) Radon transform of a(x, y) Projection at Slide 6 Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP CTU Prague 8 th December, 2004Tom Hol Filtered back-projection algorithm Based on Fourier Slice Theorem: S (w) is Fourier transform of projection P (t) A(u, v) is Fourier transform of a(x,y) Projections are filtered with ramp filter |w| and backprojected along angle to slice reconstruction Additional smoothing of projections can improve noise level Filtered projections Reconstruction Slide 7 Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP CTU Prague 8 th December, 2004Tom Hol Filtered back-projection algorithm Slide 8 Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP CTU Prague 8 th December, 2004Tom Hol Medipix-2 device with converter Reaction: 6 Li + n (2.05 MeV) + 3 H (2.72 MeV) Cross section: 940 barns (0.0253 eV) 256x256 pixels, 55x55 m 2 each, active area 1,98 cm 2 Each pixel contains 2 discriminators, 2x3-bit thresholds adjustments and 13-bit pseudo-random counter 300 m thick silicon detector Converter layer ( 6 Li) Silicon detector Bump bonding Readout chip Slide 9 Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP CTU Prague 8 th December, 2004Tom Hol Thermal neutron source NEUTRA station of spallation neutron source SINQ in Paul Scherrer Institute, Villigen, Switzerland Intensity about 10 7 neutrons/cm 2 s at proton accelerator current of 1 mA and proton energy of 590 MeV Beam cross section is 40 cm in diameter Slide 10 Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP CTU Prague 8 th December, 2004Tom Hol Lemo connector Reconstruction from 100 projections Each projection 150 s Slide 11 Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP CTU Prague 8 th December, 2004Tom Hol Potentiometer Reconstruction from 100 projections Each projection 150 s Slide 12 Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP CTU Prague 8 th December, 2004Tom Hol Tooth Reconstruction from 100 projections Each projection 150 s Slide 13 Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP CTU Prague 8 th December, 2004Tom Hol Cartridge comparison with Medipix-1 Reconstruction from 48 projections Each projection 90 s Medipix-1 64x64 pixels Each pixel 170x170 m 2 300 m thick silicon detector Neutron source Horizontal channel of the LVR-15 nuclear research reactor at Nuclear Physics Institute of the Czech Academy of Sciences at Rez near Prague. Intensity ~10 7 neutrons/cm 2 s (at reactor power of 8MW) Beam Cross section: 4 mm x 60 mm The divergence of the beam is < 0.5 Slide 14 Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP CTU Prague 8 th December, 2004Tom Hol Cartridge Medipix-1 with X-rays Reconstruction from 48 projections Each projection 30 s Medipix-1 64x64 pixels Each pixel 170x170 m 2 Slide 15 Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP CTU Prague 8 th December, 2004Tom Hol Cartridge Medipix-2 Reconstruction from 100 projections Each projection 150 s Slide 16 Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP CTU Prague 8 th December, 2004Tom Hol Conclusion and outlook Medipix-2 offers excellent properties for neutron micro- tomography very good spatial resolution and unlimited dynamic range Tomography expertiments requires synchronization of several devices. In Medisoft4 is no way to synchronize actions with other programs => complete acqusition is necessary => time demanding offline analysis It is necessary to develop flexible software for acquistion control allowing other application to access Medipix-2 device and providing interprocess synchronization Slide 17 Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP CTU Prague 8 th December, 2004Tom Hol Basic user interface (MpxCtrlUI.dll) Data sharing and process synchronization plugin Custom plugins (experiment specific) Communication plugins Client interface library User application Plugins Architecture Muros + NI card Muros HW library (MpxHw.dll) Control library (MpxCtrl.dll) Manager (MpxManager.dll) Medipix Loader (MpxLoader.exe) USB HW library, Dummy HW library, USB User application Hardware independent access to Medipix Auto-initialization and chipboard configuration handling Multiple acquisition handling (custom size stream/frame buffer, integral buffer, thread-level buffer synchronization) Callback function registration Implemented in C++, limited number of platform dependent calls, no MFC Hardware independent access to Medipix Auto-initialization and chipboard configuration handling Multiple acquisition handling (custom size stream/frame buffer, integral buffer, thread-level buffer synchronization) Callback function registration Implemented in C++, limited number of platform dependent calls, no MFC Plugin management (plugin registration, initialization, ) Provides access to MpxCtrl library, Windows messages (for convenient MFC plugins usage), tray menu Provides communication between plugins Implemented in C++ Load-time dynamic linking of MpxCtrl.dll Run-time dynamic linking of registered plugins Plugin management (plugin registration, initialization, ) Provides access to MpxCtrl library, Windows messages (for convenient MFC plugins usage), tray menu Provides communication between plugins Implemented in C++ Load-time dynamic linking of MpxCtrl.dll Run-time dynamic linking of registered plugins Medipix Manager initialization Tray menu building Forwards all incoming Win messages to Medipix Manager Load-time dynamic linking of MpxManager.dll Implemented in C++, MFC Medipix Manager initialization Tray menu building Forwards all incoming Win messages to Medipix Manager Load-time dynamic linking of MpxManager.dll Implemented in C++, MFC Basic user interface for Medipix Control Chipboard configuration management Basic data acquisition control Simple data preview Custom plugin optionally loaded by manager Load-time dynamic linking of MpxManager.dll Implemented in C++ (MFC regular DLL) Basic user interface for Medipix Control Chipboard configuration management Basic data acquisition control Simple data preview Custom plugin optionally loaded by manager Load-time dynamic linking of MpxManager.dll Implemented in C++ (MFC regular DLL) Exclusive access to HW Hardware detection and diagnostics Exports set of basic functions for hardware independent access to Medipix Single threaded Implementation in C Exclusive access to HW Hardware detection and diagnostics Exports set of basic functions for hardware independent access to Medipix Single threaded Implementation in C