HEITLER, Compton Cross-Sections, Photoelectric Cross-Sections, Pair-Production Cross-Sections, Total Cross-Sections

1 - Nature of physical problem solved: Subroutine HEITLER computes, for any element, the Compton, photoelectric, pair-production, and total microscopic cross-sections. It also computes either the Compton absorption cross-section or the Klein-Nishina differential scattering cross-section. 2 - Method of solution: The Compton cross sections are calculated theoretically from the Klein-Nishina equation. The photoelectric and pair-production cross-sections are obtained by suitable interpolation in atomic number and energy using a compilation of 25 sets (more or less) of measured cross-sections. 3 - Restrictions on the complexity of the problem: The range of atomic numbers is from 1 to 94 inclusive. The range of photon energy is from 10 keV to 20 MeV inclusive