JTomo microtomograph
The JTomo microtomograph is a fully in-house built system. It employs a Hamamatsu L12161 X-ray tube (40 kV - 150 kV, 75W) and Teledyne Shad-o-Box 6k HS flat panel detector in cone-beam geometry, combined to X-Y-Z-theta(-U-V) 6-axis sample stage. Alternatives to the flat panel are two Advacam photon counting detectors: MiniPix (Si), 256x256 pixels of 55 µm each, and WidePix 10x1 (CdTe), 2560x256 pixels of 55 µm each.
The maximum resolution (MTF 10%) is around 5 µm for a sample of 7 mm in diameter. At the other end of the scale, the device accepts samples up to 100 mm in diameter.
An XYZ stage for optional beam conditioning devices is installed and typically used, e.g., for scatter correction arrays. Experimental local beam hardening correction (signal-to-thickness transformation) using calibration plates is available, too.
The reconstructions are made with the Pi2 software and a separate graphical user interface.
The JTomo system is capable of supporting various in-situ experiments: mechanical testing stages, flow stages, humidity chambers, and temperature-controlled experiments have been made in the past and most of these are available locally. These dynamic experiments are easy to implement, as the entire system can be fully controlled with Python scripts in addition to a graphical user interface. Furthermore, there is ample space for routing all the necessary cables and hoses into the radiation safety enclosure through a labyrinth system.
An example of a typical application of JTomo is an in-situ measurement of water transport in bentonite clay. In these experiments, the clay sample is placed into a chamber, where water is allowed to enter from a specific direction. The water content and changing dry density of the bentonite sample are measured from periodically acquired X-ray tomography or radiographs of the system. This process yields 3D+time data of the liquid entering the sample.
Applications of the method can be found, e.g., in the safety assessment of bentonite buffer materials for the final disposal of radioactive waste.
