Calculation of x‐ray spectra emerging from an x‐ray tube. Part I. Electron penetration characteristics in x‐ray targets

<jats:p>The penetration characteristics of electron beams into x‐ray targets are investigated for incident electron kinetic energies in the range <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/mp4725-math-0001.png" xlink:title="urn:x-wiley:00942405:media:mp4725:mp4725-math-0001"/>. The frequency densities of electrons penetrating to a depth <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/mp4725-math-0002.png" xlink:title="urn:x-wiley:00942405:media:mp4725:mp4725-math-0002"/> in a target, with a fraction of initial kinetic energy, <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/mp4725-math-0003.png" xlink:title="urn:x-wiley:00942405:media:mp4725:mp4725-math-0003"/>, are calculated using Monte Carlo methods for beam energies of 50, 80, 100, 120 and <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/mp4725-math-0004.png" xlink:title="urn:x-wiley:00942405:media:mp4725:mp4725-math-0004"/> in a tungsten target. The frequency densities for <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/mp4725-math-0005.png" xlink:title="urn:x-wiley:00942405:media:mp4725:mp4725-math-0005"/> electrons in Al, Mo and Re targets are also calculated. A mixture of simple modeling with equations and interpolation from data is used to generalize the calculations in tungsten. Where possible, parameters derived from the Monte Carlo data are compared to experimental measurements. Previous electron transport approximations in the semiempirical models of other authors are discussed and related to this work. In particular, the crudity of the use of the Thomson‐Whiddington law to describe electron penetration and energy loss is highlighted. The results presented here may be used towards calculating the target self‐attenuation correction for bremsstrahlung photons emitted within a tungsten target.</jats:p>