The Center maintains state-of-the-art x-ray microcomputed tomography instrumentation, associated computational and visualization facilities, and significant technical expertise in a range of three-dimensional imaging and characterization areas. The Center's focus on 3D/4D monitoring of internal processes and characterization of 3D structure in natural and synthetic systems is reflected in the instrumentation available for research use.

Microcomputed Tomography

GE v|tome|x L300 multi-scale nano/microCT system

The GE v|tome|x system is a dual-tube system equipped with a 300kV unipolar microfocus X-ray tube, a 180kV nanofocus X-ray tube with transmission target assembly, and a GE DXR250 high-contrast digital flat panel detector. The high-energy xs|300 d unipolar 300kV, 500W X-ray tube uses a tungsten reflection target system. This Xray tube allows CT imaging of a range of object sizes and densities at high-resolution with a maximum feature detectability of 1 mm. The xs|300 d unipolar allows for the flexibility of conducting both low energy, high-resolution scanning and higher energy scanning for larger, denser objects. The system is also equipped with a second tube, the xs|180nf 180kV, 15W nanofocus X-ray tube. The xs|180nf uses a transmission target system to achieve nanofocus with detail detectabilities in the sub-500 nm range. The xs|180nf also uses a diamond exit window that greatly enhances data quality compared to the more common beryllium windows. The nanofocus tube includes both tungsten and molybdenum target assemblies. Molydenum targets optimize the X-ray spectrum at low acceleration voltages and enhance detectability of low density, soft materials like soft biological tissue. The v|tome|x L 300 uses a high-contrast GE DXR|250|HCD 4 megapixel (2048x2048) digital flat panel detector. This detector is mounted on a track and is automatically translated laterally so that the detector field can be doubled. This so-called “virtual detector” effectively increases the available pixel field to 4096 wide by 2048 high. The increased pixel field allows a much larger projection image to be collected so that maximum resolutions for scanning increase to approximately 1/4000th the diameter of the object being scanned.

GE_panorama.jpg

Varian BIR HD-600 OMNI-X multi-scale industrial high-resolution CT scanner

This system has been in operation since 2001 and is designed for both high resolution and flexibility. It includes dual 225 kV and 320 kV X-ray sources and a 1024x1024 pixel analog area detector with image intensifier. The micro-focus source is an X-Tek 225 kV, 225W tube with a nominal focal spot size of about 5 mm at 5W. The higher-power source is a Pantak 1600W sealed x-ray tube capable of 320 kV with the minimum focal spot of >100 mm. The OMNI-X is capable of continuously variable magnification with pixel sizes approximately 1/1000th of the sample diameter. The strength of the HD-600 is the flexibility to image objects ranging in size from 10 mm to 200 mm with a variety of material densities.

OMNI-X_microCT Scanner

Flow

The CQI maintains a range of equipment for use in fluid flow experiments. Frequently the processes studied depend on environmental conditions, typically temperature and pressure. To accommodate these studies, the center has a range of chambers, condition controllers and transducers. The Center maintains eleven X-ray transparent core holders covering sample diameters from 1 to 4 inches, and lengths up to 24 inches. These vessels can apply confining pressures up to 10,000 psi and temperatures up to 150 degrees C. Two of the vessels can apply independent axial loads for triaxial testing. Most of these have fluid access ports for multiphase fluid flow observations and can be made to accommodate additional instrumentation such as strain gages or other transducers.

Fluid pressure injection equipment consists of a range of pump systems:

  • Five precision computer-controlled dual-piston syringe pumps capable of pressures up to 3000 psi and flow rates up to 100 cc/min
  • Three additional manually controlled syringe pumps
  • Three HPLC piston pumps
  • A hydrostatic flow system for very low constant pressure injection

Confining Pressure, differential pressure, and temperature can be monitored and recorded through a system of transducers and data acquisition software. Transducers include several resistance-bridge diaphragm models ranging from 1000 to 10000 psi gauge pressure, similar differential pressure gauges with 50 to 100 psi range, additional variable reluctance differential pressure transducers with replaceable diaphragms covering a wide range of pressures, and three high-precision quartz absolute and differential pressure transducers. These can be calibrated in house against dead weight testers or high-accuracy Heise gauges. Data are recorded using dedicated software or separate DAQ systems. Flow rates are controlled by the precision pump system or by a timed fluid collection system.

Computational

The Center has dedicated computer hardware and software for reconstructing, visualizing, analyzing, and archiving CT image data. The Center maintains multiple high performance workstation computers with analytical and visualization software including Avizo, ImageJ, Matlab, as well as custom code for data analysis.