Calculate radiation dose from a source and estimate required shielding thickness for lead, concrete and water.
Radiation dose describes how much energy is deposited in tissue by ionizing radiation. The absorbed dose (in Gray, Gy) measures energy per unit mass. The equivalent dose (in Sievert, Sv) accounts for the biological effectiveness of different radiation types — alpha particles cause more damage per unit energy than gamma rays, for example. The effective dose weights different organs by their sensitivity to radiation.
Shielding follows an exponential attenuation law. Each half-value layer (HVL) of material reduces the dose rate by half. Dense materials like lead are effective gamma shields because of their high atomic number. Concrete is commonly used in facilities. Water works for neutron shielding. The number of HVLs needed is n = log₂(reduction factor), and total thickness = n × HVL.