Gamma Ray Buildup Factors in Lead-Iron and Iron-Lead Shields

摘要

Using the gamma transport code PIPE, buildup factors are evaluated in shields consisting of: iron layers of up to 40 cm thickness followed by thick lead layers; and lead layers of up to 10 cm thickness followed by thick iron layers. The source is assumed plane isotropic and four source energies were used, ranging from 0.66 MeV (caesium source) to 6 MeV. The differences between the buildup factors for exposure and equivalent dose rates are outlined. A comparison of the buildup factors in the iron-lead sequence and the lead-iron sequence shows the latter configuration to present fewer problems.