X-Ray Interactions With Matter
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| Audience/Grade: | 0-Continuing Education |
| Discipline(s): |
Bioengineering and Biomedical Engineering Chemistry Electrical Engineering Materials Engineering Nuclear Engineering Physics |
| Special Topic(s): | |
| Learning Resource Type: |
Teaching - Case Study |
| Media Type: |
Unknown |
| Author(s): |
Eric Gullikson |
| Publisher(s): |
Lawrence Berkeley National Laboratory |
| Description: | This web based software teaches the user concepts about X-ray interactions with matter. The primary interaction of low-energy x rays within matter, viz. photoabsorption and coherent scattering, have been described for photon energies outside the absorption threshold regions by using atomic scattering factors. The atomic photoabsorption cross section, � may be readily obtained from the values using the relation, � = 2 � r � � f where r is the classical electron radius, and is the wavelength. The transmission of x rays through a slab of thickness d is then given by, T = exp (- n � d), where n is the number of atoms per unit volume in the slab. The index of refraction n for a material is calculated by, n = 1 - n � r � � (f i f) / (2). These (semi-empirical) atomic scattering factors are based upon photoabsorption measurements of elements in their elemental state. The basic assumption is that condensed matter may be modeled as a collection of non-interacting atoms. This assumption is in general a good one for energies sufficiently far from absorption thresholds. In the threshold regions, the specific chemical state is important and direct experimental measurements must be made. Note also that the Compton scattering cross section is not included. The Compton cross section may be significant for the light elements (Z < 10) at the higher energies considered here (10 keV to 30 keV) - atomic scattering factor files - X-ray properties of the elements - index of refraction for a compound material - X-ray attenuation length of a solid - X-ray transmission - Of a solid - Of a gas - X-ray reflectivity - Of a thick mirror - Of a single layer - Of a multilayer - The diffraction efficiency of a transmission grating - Related calculations |
| Rating: | No Rating |
| Related Resources | |
| Version Info | |
| Publication Date: | January 1998 |
| Platform/Format: |
WWW |
| Cost: |
Free |
| Download URL: | http://www-cxro.lbl.gov/optical_constants/ |
| Metadata: |
IEEE LOM Record |
| Collection: |
NEEDS
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