In the present paper we are reporting successful absorption micro-tomography (SµCT) on microporous tungsten, an exceptionally high X-ray absorbing and scattering medium. The work is the result of a long time research effort, started in 2011, in cooperation with the European Synchrotron Radiation Facility. The motivation starts from the observation that metals with high atomic number like tungsten possess a photon transmission which is dramatically lower compared to common lower-Z metals (like iron and copper). Furthermore, complex porous structures within such highly absorbing medium are believed to increase the overall image noise with additional photon-scattering. These both effects make absorption microtomography of microporous tungsten particularly challenging, requiring to operate with a high-energy synchrotron source, long exposure times and a dedicated setup optimization. On the other hand, at the required scanning energy (> 40 keV) synchrotron detectors are known to deplete their efficiency considerably. This latter problem is asking for a dedicated solution. We are therefore proposing to select an optimum scanning energy with monochromatic light which minimizes the total number of incident photons required to achieve a satisfactory signal-to-noise ratio at the scintillator detector. The model is inspired by a previous work of Grodzins (cit.), whereas the herewith proposed extention newly introduces an energy dependent coupling effect between real scintillators and absorbing samples. The paper firstly illustrates the new model for beam energy optimization after discussing the problem of absorption microtomography of dense media. Then, it describes the experiments at beamline ID-19 of the European Synchrotron Radiation Facility (ESRF) on a plasma-sprayed tungsten specimen with variable thickness (0.3-0.7 mm). Good tomographic image quality is reported at the predicted optimum energy with capability to resolve the complex pore network and the microcracks up to a specimen thickness of 0.65 mm. An effective spatial resolution of about 3µm and limited beam hardening are also demonstrated. Considering the extreme noisy conditions and the provided theoretical background, we believe that this result is remarkable and should be considered for publication in Journal of Synchrotron Radiation. [not sure about this final sentence] "
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In the present pape r, we are repor t on the ing successful absorption micro-tomography (SµCT) on microporous tungsten, an exceptionally high X-ray absorbing and scattering medium. The work is the result of a long -term time research effort, started in 2011, in cooperation with the European Synchrotron Radiation Facility. The motivation starts comes from the observation that metals with a high atomic numbe r, like tungste n, possess have a photon transmission which is dramatically lower compared to common lower-Z metals (like iron and copper).
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In the present paper, we are reporton the ing successful absorption micro-tomography (SµCT) on microporous tungsten, an exceptionally high X-ray absorbing and scattering medium.
The work is the result of a long-termtime research effort, started in 2011, in cooperation with the European Synchrotron Radiation Facility. The moti