Typically, when a parent nucleus beta-decays into its daughter, there is some final energy available which is shared between the final products of the decay. This is called the Q value of the beta decay (Q β). The daughter nucleus doesn't necessarily end up in the ground state after the decay, this only happens when the other products have taken all the available energy with them (usually as kinetic energy). So, in general, the daughter nucleus keeps an amount of the available energy as excitation energy and ends up in an excited state associated to some energy level, as seen in the picture. The daughter nucleus can only stay in that excited state for a small amount of time (the half life of the level) after which it suffers a series of gamma transitions to its lower energy levels. These transitions allow the daughter nucleus to emit the excitation energy as one or more gamma rays until it reaches its ground state, thus getting rid of all the excitation energy that it kept from the decay.