Some Useful X-Ray Data

The measured mass absorption coefficients of Allen and Wrede for H, Be, C, N, O, F, Na, Al, Si, Cl and Br have been fitted to the ``universal law''μ/ρ=aλn+c/(1+0.048/λ),by least squares, and the values of a, n, and c tabulated. The energy distribution in the continuous x-ray spectrum in the range from 20 to 70 kv, as measured by Kirkpatrick and by Ulrey, has been recomputed, and presented graphically in a form which permits easy interpolation. The recomputation of Ulrey's data is described in some detail.