320/225 XTEK bay

The Bay The 320/225 kV Nikon XTEK bay, nominally called the “Custom Bay”, at the Henry Moseley X-Ray Imaging Facility (HMXIF) has a number of ad-vantages over a standard X-ray cabinet radiation housing. The main advantage is the ability to analyse large specimens up to 238 millimetres in cross-section. The additional height of the custom bay also permits long specimens, up to 800 mm, to be imaged via multiple scans. In these cases the scans are linked and the data are knitted together during the reconstruction stage. This technique can achieve a higher resolution than a typical single X-Ray CT scan. Two high specification 120GB RAM workstations with GPU reconstruction capability are linked to the 320/225 kV Nikon XTEK bay for rapid data reconstruction and processing. It may also be possible to image selected regions of interest within a larger specimen using this technique.

External control Unlike cabinet systems, the bay is additionally fitted with two labyrinth systems for the external control and monitoring of user-installed equipment during scanning.

Internal features The heavy duty 5-axis specimen manipulator stage that is capable of supporting specimens of 100 kg (50kg maximum weight directly on to the manipulator stage) The stage also allows the attachment of specialist rigs that are designed for in-situ 4-D analysis (compression, tension and temperature) using the range of in situ rigs that are avail-able within the facility

Three interchangeable X-ray sources:

  • The 225kV static tungsten transmission anode source
  • The 320 kV static tungsten reflection anode that allows the analysis of larger and denser specimens
  • The 225 kV static multi-metal reflection anode source has the option of copper, molybdenum, silver and tungsten targets
  • High speed detector 2k x 2k Perkin Elmer 1621-16-bit amorphous silicon flat-panel detector (XRD 1621 AN3 CT grade) fitted with an aluminium window. The detector is fitted on a mov-able arm that can be remotely controlled. General features of the detector are:

  • 200 μm pixel pitch
  • A dynamic range over 88 dB
  • Live frame rates up to 15 fps or 30fps using binning 2
  • 16 bit readout

  • 65,536 grey levels

  • Suitable for a wide range of X-Ray energies - 40 kV — 15 MV
  • Selectable gain setting

  • Galvanic isolation by fibre-optical interface.
  • Choice of targets The energy range required depends on the materials to be scanned. The 225 kV static multi-metal reflection anode source has the option of copper, molybdenum, silver and tungsten targets, giving a wide range of energy ranges.

    Range of resolutions Depending upon the sample size or the region of interest the resolution will vary from 1 to 119 microns for specimen areas with a diameter of < 10 mm and up to 238 mm diameters respectively. The graph below showing Voxel resolution vs Field of View for the 225 kV tungsten rotating transmission anode (Red) and the 225kV tungsten rotating anode (Blue) X-ray sources. Maximum field of view is limited by the manipulator travel. It should be noted that the achievable resolution will depend upon both the specimen and a number of other factors.

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