High Quality Content by WIKIPEDIA articles! In nuclear physics, a decay product (also known as a daughter product, daughter isotope or daughter nuclide) is the remaining nuclide left over from radioactive decay. Radioactive decay often involves a sequence of steps (decay chain). For example, U-238 decays to Th-234 which decays to Pa-234 which decays, and so on, to Pb-206 (which is stable):