isomeric transition; nuclear isomer decay
Technical term in nuclear physics for the decay of a nuclear isomer to a lower-energy state, often via gamma emission.
Isomeric transition is a phenomenon in which an excited atomic nucleus emits gamma rays and transitions to the ground state.
Compound of 核 (kaku, 'nucleus'), 異性体 (iseitai, 'isomer'), and 転移 (ten'i, 'transition'). A direct translation of the English term 'isomeric transition'.