Shielding design study against gas bremsstrahlung for the CLS first optics enclosures

A radiological design study of the first optics enclosure (FOE) is performed for the Canadian light source (CLS). A radiation shower is induced by a thin copper scatterer placed at the entrance of the FOE, followed by a second silicon scatterer which is set in the middle of the FOE. A lead stop is placed near the lead back wall, which is reinforced with a lead centre panel around the beam axis. To assess the radiation level outside of the FOE, the FOE is encompassed by a water phantom in which the energy deposition is estimated by a Monte Carlo simulation. The dose distributions behind the back, side walls and roof are obtained, and the thicknesses of the back wall, side wall and roof are discussed.