The Energy Dependence of the Photoelectric Attenuation Coefficient of Substances

Introduction: the photoelectric attenuation coefficient of substances is knownto depend upon the energy e of the photon and the effective atomic number of substances(zeff) as (zeffx/ey). no definitive values about these indices x, y are given inthe literature. the index x is said to lie between, 3.0 and 4.0, while for ‘y’ differentvalues have been assigned, between 3.0 and 4.0.methodology: we followed a methodology to find both the exponent y explicitly,from a formula which does not contain x. through this way, the risk of oneparameter leading to an estimation error for the other is automatically eliminated.with the value of y being unmistakably established, we determined the exponent xfor different elements.results: it was found from the nist data that ‘y’ = 3.0669 for most substanceswith low atomic number but no single value can be assigned for the exponent ‘x’.conclusions: these results help us to perform model calculations for theattenuation coefficients of different substances. they can also provide importantinputs for the diagnostic purposes in the dect method.