Backscattering technique

Cherniak D.J., Eanford W.A., and Ryerson F.J. (1991) Lead diffusion in apatite and zircon using ion implantation and Rutherford backscattering techniques. Geochim. Cosmochim. Acta 55, 1663-1673. 

The neutron backscatter technique is best performed with hydrogen-containing products. Both the source of a slow neutron and the receiver are located in the same box. The slow neutrons bounce off of protons (hydrogen ions) and are reflected back. The rate at which these neutrons are reflected back is measured, and corresponds to the hydrocarbon density in the vessel. This measurement is not affected by steel components inside—or outside—the vessel. 

The necessary uniformity of dose can be achieved with appropriate backscattering techniques. Dosimetry systems are adequate to continue the program on a realistic basis. More techniques should be perfected. Handling aspects for large quantities of fruits present the major problem (7). Cooperation between experienced food machinery builders, users, and the beam specialists should be stimulated. 

Table 4. Comparison of x-ray fluorescence experiment data (XRFE)27) with those from returned-sample analysis (RSA) and the alpha-backscatter technique (AST). See Table 1 and 2...

Tensile tests in association with 3D-video extensometer and real time light backscattering technique. 

The vertical density profile provides a means of optimizing the press operation, as well as panel performance. While initially undertaken in the laboratory, the VDP can now be measured on the moving panel as it leaves the press, using an x-ray backscatter technique (Dueholm, 1996). This is an expensive tool, but the purchase is increasingly common as the value of real time VPD information is appreciated. 

Bemer, G., A Simple Light Backscatter Technique to Determine Average Particle Size and Concentration in a Suspension , Powder Tech., 20, 133 (1978). 

In contrast, inclusions form more readily in carbonates and evaporites but these have an intrinsic tendency to experience recrystaUization or neomorphism. Leaking inclusions, precipitation of minerals inside the inclusion volume, and also necking-down phenomena may alter dramatically the internal pressure and volume ratios in the inclusions from the time of its initial entrapment, making microthermometric observations more difficult to translate directly into trapping temperature (cf. Roedder 1984 Ned-kvitne et al. 1993). This temperature is needed to decipher the time for entrapment by the use of the burial history for the trap (Karlsen et al. 1993). This type of application of inclusions as tape recorders for reservoir filling is in carbonates best done with the help of detailed cathodo-luminesence or backscatter techniques so that the various diagenetic events can be traced in detail. 

Using nucleonic level detectors These usually employ gamma ray absorption or neutron backscatter techniques, but may also use gamma ray backscatter (Sec. 14.5). A case where a gamma ray absorption indicator solved a level control problem at the base of a column has been described (71). 

Neutron backscatter techniques are suitable for locating the interface between two materials that have different hydrogen atom concentrations. Figure 14.16 shows a typical ex unple of such an application. The probe is positioned near the wall of the vessel and is moved up and down along the surface. The signals show where the interface exists. 

The most common applications of this technique in distillation and absorption columns is for liquid level and liquid level interface detection, especially when normal level-measuring techniques suffer from plugging. Neutron backscatter techniques have also been used for froth height measurements on trays and downcomers, and for measuring the top and bottom of packed beds. One case history has been described (71) where downcomer froth height measurements using the neutron backscatter technique led to a detection of downcomer deposits which caused premature flooding of the column. The author is familiar with one case where this technique successfully detected overflow of a packed tower distributor. 

Neutron backscatter techniques can detect a liquid interface far... 

Rgura 14.16 Level and interface measurement using a neutron backscatter technique (From J. S. Charlton and M. Polarski excerpted by special permission from Chemical Engineering, February 21, 1983 copyright by McGraw-Hill, Inc., New York, NY 10020.)... 

Typical profile using the neutron backscattering technique, obtained for a storage tank filled with various liquid and vapour phases, is given in Figure 3-2 (IAEA, 2002). 

W.R. Grant, R.D. Halte Jr., E.M. Liston, R.C. Robbins, E.K. Proctor Jr. Calibrated remote measurement of NO2 using the differential absorption backscatter technique. Appl. Phys. Lett. 24, 550 (1974)... 

By knowing the property-thickness relationship, X-ray (ASTMB 568-79) and optical absorption may be used to measure thickness. This is most often used as a comparative technique. The thickness-property relationship also allows emission and backscatter techniques to be used for thickness measurement. These techniques include backscatter of low... 

As a noncontacting backscattering technique, which needs access to only one side of a sample (see, for example, Figure 5(a)), Raman spectroscopy has certainly a larger potential for process control applications compared to IR spectroscopy. Comprehensive reviews of the instrumental requirements, limitations, artifaas, and practical applications of Raman spectroscopy for process analysis have appeared in the literature and in what follows only a few selected examples will be discussed. 

---