Photon interaction and energy absorption in glass: A transparent gamma ray shield

The effective atomic number, Zeff, the effective electron density, Ne,eff, and the energy dependence, ED, have been calculated at photon energies from 1 keV to 1 GeV for CaO–SrO–B2O3, PbO–B2O3, Bi2O3–B2O3, and PbO–Bi2O3–B2O3 glasses with potential applications as gamma ray shielding materials. For medium-Z glasses, Zeff is about constant and equal to the mean atomic number in a wide energy range, typically 0.3 < E < 4 MeV, where Compton scattering is the main photon interaction process. In contrast, for high-Z glasses there is no energy region where Compton scattering is truly dominating. Heavy-metal oxide glasses containing PbO and/or Bi2O3 are promising gamma ray shielding materials due to their high effective atomic number and strong absorption of gamma rays. They compare well with concrete and other standard shielding materials and have the additional advantage of being transparent to visible light. The single-valued effective atomic number calculated by XMuDat is approximately valid at low energies where photoelectric absorption is dominating.