Continuous Spectral Energy Distribution within the X-ray Tube

Continuous spectral energy distribution of x-radiation as emitted from the target of a Coolidge tube at right angles to the beam of electrons, has been determined from the distribution curve obtained with a rock salt crystal spectrometer and a methyl iodide ionization chamber, by applying the following corrections: (1) For superposed higher orders (determined from polychromat curves and also from the absorption of the complex rays in aluminum); (2) for incompleteness of absorption in the ionization chamber (determined by absorption experiments); (3) for absorption by glass wall, by air, and by aluminum window (determined by observation or by computation); (4) for reflecting power of the rock salt crystal (obtained from curve derived from results of various investigators). The final curves show maxima at 0.445 and 0.503A for 71 and 51 kv respectively. Comparison of these curves with those given by the theories of Behnken, March, and Davis, shows agreement with none. The maxima correspond to the equation ${\lambda }_m=k+k^{\prime }{\lambda }_{\circ }$, where ${\lambda }_{\circ }$ is the quantum wave-length.