Skyshine

(Radiation) skyshine describes the ionizing radiation emitted by a nuclear technical or medical facility, reaching the facility's surroundings not directly, but indirectly through reflection and scattering at the atmosphere back to Earth's surface.

[2][3] This effect can also happen when the shielding in the vault room of a linear particle accelerator in radiation therapy is not sufficient to reduce the intensity of the primary incident beam down to a very low level.

This skyshine can be measured by a medical physicist at the position of the pedestrian standing on the ground in the nearby parking lot.

Regardless of whether the upward incident beam is shaped like a circle, square or rectangle, specific calculation formalism has been described.

Depending on the energy of the scattering radiation, the intensity maximum is reached at different distances from the vault.