Beta decay can involve the emission of either electrons or positrons. The electrons or positrons emitted in β - decay do not exist inside the nucleus. They are only created at the time of emission, They are only created at the time of emission Just as photons are created when an atom makes a transition from higher to a lower energy state. In negative β decay a neutron in the nucleus is transformed into a proton, an antineutrino Hence in radioactive decay process the negatively charged, emitted b - particles are the electrons produced as a result of the decay of neutrons present inside the nucleus.