Physics

Problem

An excited nucleus

^{26}_{13}\text{Al}^*

decays to its ground-state daughter by simultaneously emitting a

\gamma

ray and undergoing positron emission:

^{26}_{13}\text{Al}^* \;\to\; ^{26}_{12}\text{Mg} + \gamma + e^+ + \;?

Write the symbol of the lepton required to complete the nuclear equation.