In the gamma decay of a nucleus

Gamma decay is a nuclear process where an excited nucleus transitions to a lower energy state by emitting high-energy electromagnetic radiation known as gamma rays. Unlike alpha decay, which reduces the mass number by four and the atomic number by two, or beta decay, which alters the atomic number, gamma radiation consists of photons that are both chargeless and massless. Consequently, the emission of gamma rays does not alter the number of protons or neutrons within the nucleus. Because the composition of the nucleus remains identical in terms of its constituent nucleons, neither the atomic number (Z) nor the mass number (A) undergoes any change. The parent and daughter nuclei remain the same chemical element, differing only in their internal energy levels.