[B._Beckhoff,_et_al.]_Handbook_of_Practical_X-Ray_(b-ok.org).pdf

Dynamic range w since the dynamic range of counting

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Dynamic Range W : Since the dynamic range of counting rate is wide compared to EDXRF, the measurement is possible under the same excitation conditions of X-ray source from a very-small-quantity ingredient to the main ingre- dient. In order to realize the high precision analysis of the main ingredi- ents, it is necessary to suppress statistical error in X-ray counting. The upper limit of counting rate is 1 or 2 million cps or more in WDXRF system. Since this value is large compared to EDXRF, the measurement that suppresses the error becomes easy. E : The saturation of counting rate of the ED detector at high-count rate restricts the performance in a certain kind of application. It is not suitable when high intensity is needed in order to take high precision measurement of the main ingredients etc. Measurable Element Range W : Measurable element range of WDXRF is down to beryllium owing to the ultrathin (sub- µ m) polymer detector window and a synthetic multilayer E : Practical element range is sodium and heavier for usual EDXRF, except for EDXRF with special specification.
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302 References Equipment Composition and Dimension W : Generally equipment size becomes large and is expensive because of the using of an optical system for wavelength dispersion and high power unit for X-ray tube. E : Construction of EDXRF equipment is simple and can be miniaturized. Portable types and even handheld types have been already realized. Detecting Efficiency, Smallest Limit of Sample Size W : Since the X-ray acceptance solid angle from a sample is small because of the using of a collimator system including a monochromator crystal that has low reflectivity of X-rays, the detection efficiency of fluorescent X-rays from a sample is very small. Therefore, generally it is unsuitable for measurement of feeble fluorescent X-rays, i.e., analysis of a small quantity sample or a small area. Since detection efficiency is so small, a high power source of X-rays is required. E : It is possible to make the detector position closer to a sample and the acceptance solid angle of the fluorescent X-rays from the sample can be enlarged. Therefore high sensitivity measurement for a small area or a small amount of sample quantity can be performed. References 1. Rutherford E, Geiger F, Proc R Soc 81 , 141 (1908) 2. Fiorini C, Longoni A, Perotti F, Labanti C, Rossi E, Lechner P, Soltau H, Str¨uder L, A monolithic array of silicon drift detectors coupled to a single scintillator for γ -ray imaging with sub-millimeter position resolution, Nucl In- strum Meth A 512 , 265–271 (2003) 3. Pell EM, J Appl Phys 31 , 1675 (1960) 4. Str¨uder L, Meidinger N, Stotter D, Kemmer J, Lechner P, Leutenegger P, Soltau H, Eggert F, Rhode M, Sch¨ulein T, High-resolution X-ray spectroscopy close to room temperature, Microsc Microanal 4 , 622–631 (1999) 5. Angloher G, Hettl P, Huber M, Jochum J, v. Feilitzsch F, M¨oßbauer RL, Energy resolution of 12 eV at 5.9 keV from Al-superconducting tunnel junction detectors, J Appl Phys 89 , 1425–1429 (1999) 6. Peacock A, Verhoeve P, Rando N, van Dordrecht A, Taylor BG, Erd C, Perry-
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