Update of photoelectric absorption coefficients in the tables of McMaster

2005 ◽  
Vol 35 (1) ◽  
pp. 52-56 ◽  
Author(s):  
Abdallah Shaltout ◽  
Horst Ebel ◽  
Robert Svagera
Keyword(s):  
Photoelectric Absorption ◽  
Absorption Coefficients

Numerical description of photoelectric absorption coefficients for fundamental parameter programs

2003 ◽  
Vol 32 (6) ◽  
pp. 442-451 ◽  
Author(s):  
Horst Ebel ◽  
Robert Svagera ◽  
Maria F. Ebel ◽  
Abdallah Shaltout ◽  
John H. Hubbell
Keyword(s):  
Fundamental Parameter ◽  
Photoelectric Absorption ◽  
Absorption Coefficients

THE ABSORPTION OF GAMMA-RAYS FROM Co60

1947 ◽  
Vol 25a (6) ◽  
pp. 303-314 ◽  
Author(s):  
W. V. Mayneord ◽  
A. J. Cipriani
Keyword(s):  
Absorption Coefficient ◽  
Atomic Number ◽  
Gamma Rays ◽  
Heavy Elements ◽  
Photoelectric Absorption ◽  
Lead Absorber ◽  
Absorption Coefficients ◽  
Cobalt Radiation ◽  
Good Agreement ◽  
Made In

Measurements of the absorption of gamma-rays from Co60 and radium have been made in a number of materials. Variation of absorption coefficient of the gamma-rays from radium with thickness of lead absorber is in agreement with recent experimental determinations. The gamma-rays from Co60 are approximately monochromatic and are therefore suitable for testing theoretical absorption formulae. The absorption coefficient per electron for materials of atomic number equal to or less than that of aluminium was in agreement with the Klein–Nishina formula, assuming the cobalt radiation to consist of two lines at 1.10 and 1.30 Mev. respectively. The photoelectric absorption coefficients per electron for heavy elements are in good agreement with the theory developed by Hulme, McDougall, Buckingham, and Fowler. This coefficient varies approximately as Z3.5.

scholarly journals Absorption of radium (B+C) gamma-rays

1945 ◽  
Vol 183 (994) ◽  
pp. 338-355 ◽  
Keyword(s):  
Gamma Rays ◽  
Electron Pair ◽  
Gamma Ray ◽  
Wave Length ◽  
Photoelectric Effect ◽  
Pair Formation ◽  
Photoelectric Absorption ◽  
Absorption Coefficients ◽  
Length Range ◽  
Effective Wave

New measurements of the absorption of filtered gamma-rays from radium (B + C) in aluminium, carbon and lead have been made. A small condenser type of ionization chamber has been used, which overcomes many of the difficulties usually inherent in this kind of measurement. Detailed consideration has been given to the corrections which must be applied to ionization measurements before absorption coefficients can be calculated. From the most recent theories of absolution by scattering, photoelectric effect, and electron pair formation, total absorption coefficients for lead over the wave-length range concerned have been calculated. The problem of the effective wave-length of a filtered heterogeneous gamma-ray beam is discussed in some detail, and a proposed method of estimation put forward. Comparison of the calculations of µ / ρ with the experimental figures indicates that the photoelectric absorption rises more rapidly with increasing wave-length than is predicted by theory.

scholarly journals The absorption of monochromatic X-ray beams, of wave-length in the region 50 to 20 X -units, in lead, tin, copper, and iron

1935 ◽  
Vol 152 (876) ◽  
pp. 402-417 ◽  
Author(s):  
John Read ◽  
John Cunningham McLennan
Keyword(s):  
Absorption Coefficient ◽  
Atomic Number ◽  
Wave Length ◽  
Detailed Account ◽  
Photoelectric Absorption ◽  
Absorption Coefficients ◽  
X Ray ◽  
Method Of Measurement ◽  
Absorption Measurements

In a previous paper an account has been given of the measurement of the absorption of monochromatic X-ray beams of wave-length in the region 50 to 20 x -units, in carbon and aluminium. The relation of the measured coefficient of absorption to the wave-Iength did not differ from that predicted by the Klein-Nishina formula by more than 1%. The method used in that experiment has been improved, and used to measure the absorption coefficients of lead, tin, copper, and iron for similar monochromatic beams. Because lead has been used very extensively for absorption measurements the primary aim has been to measure as accurately as possible the dependence of its absorption coefficient on the wave-length of the radiation. It has not been possible to make such accurate measurements on tin, copper, and iron, but enough data has been obtained to determine the variation of the photoelectric absorption coefficient per electron with the atomic number of the absorbing element, with fair accuracy, for radiation in this region of wave-lengths. Since these absorption coefficients may find considerable application, it is considered well to give a more detailed account of the method of measurement, so that an independent judgment of their reliability may be made.

A Determination of Screening Constants for Incomplete Atomic Shells of Elements Z = 2 to 23 from Experimental Ionization Potentials — X-ray Photoelectric Mass Absorption Coefficients for Elements Z = 6 to 15 for 33 Characteristic Energies between 1 and 25 keV

1976 ◽  
Vol 31 (8) ◽  
pp. 887-897 ◽  
Author(s):  
J. D. Stephenson
Keyword(s):  
Cross Sections ◽  
Ionization Potentials ◽  
Absorption Cross ◽  
Photoelectric Absorption ◽  
Absorption Coefficients ◽  
Spin Doublet ◽  
X Ray ◽  
Mass Absorption ◽  
Comparison With Experiment

AbstractA method is proposed, which primarily determines screening constants for incomplete atomic shells from the experimental ionization potentials of spin-paired Pauli-type orbitals. The method is complimentary and in addition to the standard Sommerfeld approach, which derives screening constants from X-ray spin doublet term differences. Atomic photoelectric absorption cross sections are computed from screened hydrogen-like eigenfunctions for low atomic number elements Z = 6 to 15, using a range of incident photon energies between 1 and 30 keV. Comparison with experiment and alternate more exact theories shows, that improved cross sections are obtained for the more important incomplete L-shell contributions. X-ray photoelectric mass absorption coefficients for low Z elements (Z= 6 to 15), employing 33 characteristic X-ray energies {NiKα (0.852 keV) to AgKβ (24.942 keV)}, are given.

scholarly journals The scattering of hard gamma rays.—Part II

1931 ◽  
Vol 130 (814) ◽  
pp. 524-541 ◽  
Keyword(s):  
Wave Length ◽  
High Energy ◽  
Photoelectric Absorption ◽  
Absorption Coefficients ◽  
Rapid Variation ◽  
Atomic Nuclei ◽  
Usual Manner ◽  
Very High Energy ◽  
Γ Rays ◽  
The Difference

Three papers have recently appeared describing investigations of the absorption of the very hard γ-rays from thorium C˝ in a number of elements, and in each case the conclusion was drawn that the results indicate that these very high energy quanta are capable of interacting with certain atomic nuclei. The three sets of experimental results do not agree in detail, but in each case the trend of the variation of absorption coefficient with atomic number is very different form the Z 3 law characteristic of photoelectric absorption. Moreover, the difference between the absorption coefficients per electron in heavy and light elements, which has hitherto been attributed to photoelectric absorption, is nearly as great for the hard thorium C˝ γ-rays ( hv =2·65. 10 6 ε-volts), as for the much softer redium C γ-rays ( hv ~ 1·8. 10 6 ε-volts), in marked contrast with the rapid variation with wave-length observed in the softer γ-ray region of the spectrum. Very little is at present know concerning the magnitude of the photo-eletric effect in the γ-rays region, and since absorption coefficients measured in the usual manner are the sum of two terms referring respectively to scattering and to photoelectric absorption, it is essential for the further elucidation of the problem to study the actual scattered radiation.

Interfacial properties of GaSb/InAs superlattices

1993 ◽  
Vol 51 ◽  
pp. 826-827
Author(s):  
M. E. Twigg ◽  
B. R. Bennett ◽  
J. R. Waterman ◽  
J. L. Davis ◽  
B. V. Shanabrook ◽  
...  
Keyword(s):  
Gaas Substrate ◽  
Molecular Beam ◽  
Infrared Detector ◽  
Interfacial Properties ◽  
Ex Situ ◽  
X Ray Diffraction ◽  
Absorption Coefficients ◽  
X Ray ◽  
Short Period ◽  
High Optical Absorption

Recently, the GaSb/InAs superlattice system has received renewed attention. The interest stems from a model demonstrating that short period Ga1-xInxSb/InAs superlattices will have both a band gap less than 100 meV and high optical absorption coefficients, principal requirements for infrared detector applications. Because this superlattice system contains two species of cations and anions, it is possible to prepare either InSb-like or GaAs-like interfaces. As such, the system presents a unique opportunity to examine interfacial properties.We used molecular beam epitaxy (MBE) to prepare an extensive set of GaSb/InAs superlattices grown on an GaSb buffer, which, in turn had been grown on a (100) GaAs substrate. Through appropriate shutter sequences, the interfaces were directed to assume either an InSb-like or GaAs-like character. These superlattices were then studied with a variety of ex-situ probes such as x-ray diffraction and Raman spectroscopy. These probes confirmed that, indeed, predominantly InSb-like and GaAs-like interfaces had been achieved.

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