# X-Ray and Gamma-Ray Data

**J. H. Hubbell and S. M. Seltzer**

Tables and graphs of computed photon mass attenuation coefficients and mass energy-absorption coefficients from 1 keV to 20 MeV are presented for all of the elements (Z = 1 to 92) and for 48 compounds and mixtures of radiological interest. These coefficients are basic quantities used in calculations of the penetration and the energy deposition by photons (x-ray, gamma-ray, bremsstrahlung) in biological, shielding, and other materials.

**M. J. Berger and J. H. Hubbell**

This database can be used to calculate photon cross sections for scattering, photoelectric absorption and pair production, as well as total attenuation coefficients, in any element, compound or mixture, at energies from 1 keV to 100 GeV. This is a web version of the PC based program XCOM (also called NIST Standard Reference Database 8 - XGAM).

**J. H. Hubbell**

This bibliography contains papers (1907-1995) reporting absolute measurements of photon (XUV, x-ray, gamma-ray, bremsstrahlung) total interaction cross sections or attenuation coefficients for the elements and some compounds used in a variety of medical, industrial, defense, and scientific applications. The energy range covered is from 10 eV to 13.5 GeV.

**C. T. Chantler**

The primary interactions of x-rays with isolated atoms from Z = 1 (hydrogen) to Z = 92 (uranium) are described and computed within a self-consistent Dirac-Hartree-Fock framework. The results are provided over the energy range from either 1 eV or 10 eV to 433 keV, depending on the atom. Self-consistent values of the f1 and f2 components of the atomic scattering factors are tabulated, together with the photoelectric attenuation coefficient [*µ/ρ*]_{PE} and the K-shell component [*µ/ρ*]_{K}, the scattering attenuation coefficient [*µ/ρ*]_{(coh + inc)}, the mass attenuation coefficient [*µ/ρ*]_{tot}, and the linear attenuation coefficient [*µ*]_{tot}, as functions of energy and wavelength. Also, f2, [*µ/ρ*]_{PE}, [*µ/ρ*]_{tot}, and [*µ*]_{tot} are available for compounds.

**R. D. Deslattes, E. G. Kessler, Jr., P. Indelicato, L. de Billy, E. Lindroth, and J. Anton**

This X-ray transition table provides the energies and wavelengths for the K and L transitions connecting energy levels having principal quantum numbers *n* = 1, 2, 3, and 4. The elements covered include *Z* = 10, neon to *Z* = 100, fermium. There are two unique features of this database: (1) all experimental values are on a scale consistent with the International System of measurement (the SI) and the numerical values are determined using constants from the most recent Recommended Values of the Fundamental Physical Constants: 1998 and (2) accurate theoretical estimates are included for all transitions.