Scattering suppression

G.D.J. Phillies, Experimental demonstration of multiple-scattering suppression in quasielastic-light-scattering spectroscopy by homodyne coincidence techniques. Phys. Rev. A 24(4), 1939-1943 (1981b). doi 10.1103/PhysRevA.24.1939... 

Efficient scatter suppression and additional correction procedures are essential for C-arm CT to achieve CT-like image quality. A variety of scatter correction approaches exist. They comprise measurement techniques, software models, and hybrid approaches (Ning et al. 2002 Siewerdsen et al. 2006 Zhu et al. 2008). Since measurement techniques require additional hardware, software approaches are often preferable. Fast and efficient algorithms are available that operate directly on the projection images acquired (Zellerhoff et al. 2005 Rinkel et al. 2007). Iterative approaches appear promising to obtain further improvements beyond state-of-the art scatter correction methods (Kyriakou et al. 2006). 

Ning R, Tang X, Conover DL (2002) X-ray scatter suppression algorithm for cone-beam volume CT. In Medical Imaging 2002 Physics of Medical Imaging. San Diego, CA, pp 774-781... 

Phillies, G. D., Experiment Demonstration of Multiple-scattering Suppression in Quasielastic-light-scattering Spectroscopy by Homodyne Coincidence Techniques, Phys. Rev. A, 1981,24, 1939-1942. 

Due to the rather stringent requirements placed on the monochromator, a double or triple monocln-omator is typically employed. Because the vibrational frequencies are only several hundred to several thousand cm and the linewidths are only tens of cm it is necessary to use a monochromator with reasonably high resolution. In addition to linewidth issues, it is necessary to suppress the very intense Rayleigh scattering. If a high resolution spectrum is not needed, however, then it is possible to use narrow-band interference filters to block the excitation line, and a low resolution monocln-omator to collect the spectrum. In fact, this is the approach taken with Fourier transfonn Raman spectrometers. 

It is convenient to set Ap1 = 1, L = d - -dq = 1. Rounding errors are suppressed by replacing die intensity by 1/s2 (Porod s law) for big arguments (s > 8). A smooth phase transition zone (in all the example curves dz = 0.1) is considered by multiplication with exp (2nsdz/3)2 j. From this one-dimensional scattering intensity die correlation function is obtained by Fourier transformation. 

Time-gated detection offers the possibility to suppress background signals correlated with the excitation pulse. Direct and multiple scattered excitation light as well as Raman scattering reaches the detector at t 0, and can be effectively suppressed by opening the first gate a few hundred picoseconds after t = 0. 

Taylor and Zeitlin [43] described an X-ray fluorescence procedure for the determination of total sulfur in seawater. They studied the matrix effects of sodium chloride, sodium tetraborate, and lithium chloride and show that the X-ray fluorescence of sulfur in seawater experiences an enhancement by chloride and a suppression by sodium that fortuitously almost cancel out. The use of soft scattered radiation as an internal standard is ineffective in compensating for matrix effects but does diminish the effects of instrument variations and sample inhomogeneity. 

In fact, the latter is the leading contribution to Gutzwiller s trace formula (Gut-zwiller, 1990), namely the contribution of the two-bounce periodic orbit between the two spheres without repetition, with the action Spo(k) = 2(r—2d)k where 2 (r — 2a) is the length of the geometric path. Note that the semiclassical result is suppressed by a factor of 1/4 in comparison to the small-scatterer one. 

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