DP Winkoun | PubMed Health

PubMed2000

Effective atomic numbers for W/Cu alloy using transmission experiments

Attenuation studies on pure elements are straightforward and extensive data sets are available in the literature. However, studies on alloys are meagre due to the nonavailability of alloys of known composition in suitable form. Such studies are useful in estimating effective atomic numbers and to verify the validity of the mixture rule. Empirical expressions for these have been reported in the literature but several discrepancies have been noted. In the present study, transmission experiments were conducted in a narrow beam geometry for the photon energy range 60-400 keV, evaluating the effective atomic numbers for W/Cu alloy of two compositions, 65/35 and 60/40.

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PubMed2000

On discrepancies in atomic photoeffect cross sections in the low photon energy region

Studies on photon interaction with matter provide a wealth of data for various applied scientific fields. While large amounts of compiled data are available on photon cross sections, significant discrepancies have been observed at very low photon energies, especially in the region of absorption edges; the cross section in some elements shows approximately 10% variation with theory. In the present study, attenuation studies have been made for energies below 60 keV for the elements Zr, Pd, Cd, In, and Ta, these being situations in which discrepancies have been noted. Use has been made of a narrow beam, good geometry situation, coupled with a Freolectric cooled Si(Li) detector attached to a System 100 Canberra multichannel analyser. Total photon and total photoelectric cross sections have been deduced and compared with theory.

Journal Article↗