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Measurements of atomic rayleigh scattering cross-sections: a new approach based on solid angle approximation and geometrical efficiency

Rao, Donepudi Venkateswara and Takeda, Tohoru and Itai, Yuji and Akatsuka, Takao and Seltzer, Stephen M. and Hubbell, John Howard and Cesareo, Roberto and Brunetti, Antonio and Gigante, Giovanni Ettore (2002) Measurements of atomic rayleigh scattering cross-sections: a new approach based on solid angle approximation and geometrical efficiency. Physica Scripta, Vol. 65 (5), p. 398-409. eISSN 1402-4896. Article.

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DOI: 10.1238/Physica.Regular.065a00398

Abstract

Atomic Rayleigh scattering cross-sections for low, medium and high Z atoms are measured in vacuum using x-ray tube with a secondary target as an excitation source instead of radioisotopes. Monoenergetic Kα radiation emitted from the secondary target and monoenergetic radiation produced using two secondary targets with filters coupled to an x-ray tube are compared. The Kα radiation from the second target of the system is used to excite the sample. The background has been reduced considerably and the monochromacy is improved. Elastic scattering of Kα x-ray line energies of the secondary target by the sample is recorded with Hp Ge and Si (Li) detectors. A new approach is developed to estimate the solid angle approximation and geometrical efficiency for a system with experimental arrangement using x-ray tube and secondary target. The variation of the solid angle is studied by changing the radius and length of the collimators towards and away from the source and sample. From these values the variation of the total solid angle and geometrical efficiency is deduced and the optimum value is used for the experimental work. The efficiency is larger because the x-ray fluorescent source acts as a converter. Experimental results based on this system are compared with theoretical estimates and good agreement is observed in between them.

Item Type:Article
ID Code:5202
Status:Published
Refereed:Yes
Uncontrolled Keywords:Anomalous dispersion, form factors
Subjects:Area 02 - Scienze fisiche > FIS/07 Fisica applicata (a beni culturali, ambientali, biologia e medicina)
Divisions:001 Università di Sassari > 03 Istituti > Matematica e fisica
001 Università di Sassari > 03 Istituti > Igiene e medicina preventiva
Publisher:IOP on behalf of the Royal Swedish Academy of Sciences for the Science Academies and the Physical Societies of the Nordic Countries
eISSN:1402-4896
Copyright Holders:© IOP Publishing
Deposited On:09 Dec 2010 10:48

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