Problems associated with the measurement of X-ray attenuation coefficients. II. Carbon. Report on the International Union of Crystallography X-ray Attenuation Project

Measurements are reported of the mass attenuation coefficient of carbon taken by laboratories participating in the International Union of Crystallography X-ray Attenuation Project. Data resulting from a similar study using silicon were published earlier [Creagh & Hubbell (1987). Acta Cryst. A43, 102-112]. The data are self consistent, for the most part, to 0.5% for the energy range 6 to 60 keV, and accords well with earlier experimental data. These data are about 3% less than the theoretically calculated data [Saloman & Hubbell (1986). X-ray Attenuation Coefficients (Total Cross Sections). Comparison of the Experimental Data Base with the Recommended Values of Henke and the Theoretical Values of Scofield from 0.1 to 100 keV. Report NBSIR 86-3431. US Department of Commerce, NBS, Gaithersburg, MD, USA; Berger & Hubbell (1987). XCOM. Photon Cross Sections on a Personal Computer. Report NBSIR 87-3597. US Department of Commerce, Gaithersburg, MD, USA] over the energy range for which measurements were made. Hence carbon appears to be an example in which the renormalization, always a decrease, of Scofield's photo-effect calculations [Scofield (1973). Report UCRL-51236. Lawrence Livermore Laboratory, Livermore, California, USA], as was implemented by Hubbell [Int. J. Appl. Radiat. Isot. (1982), 33, 1269-1290], would improve agreement with measured data.