Which statement about Sky Shine is true?

Which statement about Sky Shine is true?

• A. Can created elevated dose rates away from the source
• B. Caused by the scatter of gammas in air
• C. Occurs when radiation is directed upward
• D. None of the above

Answer: (A)

Sky shine describes the dose you can measure on the ground at locations away from a source because gamma photons have scattered in the air and then come back downward toward the ground. The defining point is the observable increase in dose at distances away from the source, not just in the immediate vicinity of the source. This happens when photons interact with air molecules (primarily via Compton scattering), changing direction and sometimes energy, so some scattered photons are redirected toward the ground and add to the local dose there. Because of this downward-scattered component, elevated dose rates can appear away from the source, which is the key feature of sky shine. While scattering in air is part of the mechanism, the important takeaway is the resulting elevated ground-level dose at distance from the source, not necessarily the direction of the original radiation.

Sky shine describes the dose you can measure on the ground at locations away from a source because gamma photons have scattered in the air and then come back downward toward the ground. The defining point is the observable increase in dose at distances away from the source, not just in the immediate vicinity of the source. This happens when photons interact with air molecules (primarily via Compton scattering), changing direction and sometimes energy, so some scattered photons are redirected toward the ground and add to the local dose there. Because of this downward-scattered component, elevated dose rates can appear away from the source, which is the key feature of sky shine. While scattering in air is part of the mechanism, the important takeaway is the resulting elevated ground-level dose at distance from the source, not necessarily the direction of the original radiation.