Ray Transmission

If a beam of X-rays is directed at an oil-filled gap bounded by material which is opaque to the X-ray beam, then a quantitative measurement of the X-ray flux transmitted through the gap can be used to assess the thickness of the oil film. The method as applied to two rolling disks by Sibley and Orcutt [17] is illustrated diagrammatically in Fig, 6-12. A collimated monochromatic beam of X-rays is passed through a set of adjustable slits to deliver a square beam of known cross-section 

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Hanke, R. B5bel, F. Determination of material flaw size by intensity evaluation of polychromatic X-ray transmission. NDT-I-E International, Vol. 25(2), 1992, pp. 87-93. 

Considering existing microscopical techniques, one can find that non-destmctive information from the internal stmcture of an object in natural conditions can be obtained by transmission X-ray microscopy. Combination of X-ray transmission technique with tomographical reconstmction allows getting three-dimensional information about the internal microstmcture [1-3]. In this case any internal area can be reconstmcted as a set of flat cross sections which can be used to analyze the two- and three-dimensional morphological parameters [4]. For X-ray methods the contrast in the images is a mixed combination of density and compositional information. In some cases the compositional information can be separated from the density information [5]. Recently there has been a... 

A first example of application of microtomography is taken from life sciences. Here X-ray microscopy and microtomography allows to reconstruct the internal three-dimensional microstructure without any preparation and sometimes even of living objects. Fig. la shows an X-ray transmission microscopical image of bone (femoral head). Several reconstructed cross-sections are shown in Fig.lb. Fig.lc shows the three-dimensional reconstruction of this bone. 

Another application areas of microtomography are biology and agriculture. Fig.4a shows an X-ray transmission image through the tulip bulb in wet conditions. Damaged area can be found in the surface of this bulb. Fig.4b shows the reconstructed cross section with information about depth of damaged volume. 

Instead of monitoring x-ray transmission, some instmments use visible light to monitor concentration (53). This optical technique is generally referred to as turbidimetry or photoextinction. Light is usually used for low particle concentrations and detection of low molecular weight particles. 

Numerous texts and a wealth of literature exist that describe many approaches to X-ray CT imaging. Examples include Refs [2—4]. All approaches involve a large number of X-ray transmission measurements of the item being imaged. In addition to measuring transmission at different positions of the item, all these measurements are then repeated at a large number of different trajectory directions of the incident X-ray beams. 

For in situ x-ray diffraction measurements, the basic construction of an electrochemical cell is a cell-type enclosure of an airtight stainless steel body. A beryllium window, which has a good x-ray transmission profile, is fixed on an opening in the cell. The cathode material can be deposited directly on the beryllium window, itself acting as a positive-electrode contact. A glass fiber separator soaked in liquid electrolyte is then positioned in contact with the cathode followed by a metal anode (3). A number of variations and improvements have been introduced to protect the beryllium window, which is subject to corrosion when the high-voltage cathode is in direct contact with it. 

Method of Determining Foam Levels. A gamma ray transmission technique was used to determine liquid levels and density profiles and also to establish the presence of foam in vessels and pipework... 

In another technique know n as X-ray transmission asymmetric crystal topography, changes in defect structure during polymerization of single crystals have been studied. 

As illustrated in Fig 1, in a 7-ray transmission gauge the number of 7-rays from a source not absorbed by the sample is measured by an appropriate detector. The absorption process is exponential and is expressed by ... 

As a simple example of how one would use Tables 1—5 for design of a 7-ray transmission gauge, let us select the best available radionuclide source to measure density changes in a cylinder of Comp B, 6cm in thickness. From eq (2), the 7-ray absorption coefficient for maximum sensitivity is 1/px or 1/1.67(6) - 0.0998. 

Fig 4 Gamma-Ray Transmission Gauge for Burning Rate Measurement in Rocket Motors... 

Fig 5 Relative Propellant Thickness vs Burning Time Using 7-Ray Transmission Gauge... 

Typical scans of an M-55 detonator are reproduced in Fig 7, showing the rate meter plots corresponding to the y-ray transmission profile thru the detonator. Starting with copper as a standard, a large increase in transmission is obtained as the beam transverses thru the RDX layer, and a corresponding decrease occurs thru... 

Detection of Base Separation in Artillery Shell by Gamma-Ray Transmission (Ref 15)... 

Fig 11 Sketch of y-Ray Transmission Gauge for Base Separation Detector... 

In (8) and (9), I is the intensity scattered by one electron, and Sr are the specific surfaces, or surface areas per unit mass of coal, of the macropores and transition pores, respectively the constant C. is proportional to the weak but constant scattering from the micropores b is a constant characterizing the micropore dimensions M and A are respectively the mass of the sample and its cross-section area perpendicular to the incident beam T is the x-ray transmission and a is a constant inversely proportional to the average dimensions of the transition pores. The factor 1/T is included in (9) to take account of the absorption of x-ray in the samples, since (3) was developed under the assumption that the samples were non-absorbing. The transmission T can be expressed—... 

Figure 4.3.6 Principle of two in situ cells that are optimized for the spectroscopic studies and the catalytic experiments the X-ray transmission image is recorded by an X-ray eye, and the calculated profile of the methane concentration is estimated for 1% CH.4/4% 02/He on a pellet of 1 mm thickness and catalyst particles of 100 pm at 500°C (taken from ref. [29]).

A gamma-ray transmission technique was used by Calderbank (1958) to determine the point gas holdup. The application to holdup measurements depends on the relationship... 

FIGURE 7 X-ray transmission through 02 and butane (calculated according to Hoffman et al. (1982)). 

Several of the interesting physical properties of organic conductors (especially transport properties) are expected to be sensitive to crystal defects. It is thus surprising that little has been done up to now to assess crystal quality. For example, a technique that may be used is x-ray transmission topography, a powerful method to obtain information about the internal perfection of not too small crystals, since it provides direct observation of defects. 

CSIRO Minerals has developed a particle size analyzer (UltraPS) based on ultrasonic attenuation and velocity spectrometry for particle size determination [269]. A gamma-ray transmission gauge corrects for variations in the density of the slurry. UltraPS is applicable to the measurement of particles in the size range 0.1 to 1000 pm in highly concentrated slurries without dilution. The method involves making measurements of the transit time (and hence velocity) and amplitude (attenuation) of pulsed multiple frequency ultrasonic waves that have passed through a concentrated slurry. From the measured ultrasonic velocity and attenuation particle size can be inferred either by using mathematical inversion techniques to provide a full size distribution or by correlation of the data with particle size cut points determined by laboratory analyses to provide a calibration equation. 

The method was used, in combination with a gamma ray transmission technique, for particle size applications in alumina plants [271] and has been tested on a variety of mineral and paint slurries giving good agreement with laser diffraction measurements. 

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