Electron Pair Creation by a Spherically Symmetrical Field

Abstract

IN the nuclear reaction F¹⁹(p,α)O¹⁶, the oxygen nucleus can be produced in an excited state with an excitation energy of 5·9 MeV. The transition from this state to the ground state of O¹⁶ does not occur, as normally, by the emission of γ-radiation, but by the creation of electron-positron pairs¹, this fact being interpreted as meaning that its excited state has zero total angular momentum (J), and since its ground state also has zero J, a single γ-radiation transition between the two states is impossible². Alternative, competitive processes such as emission of two quanta or a two-step transition via a state of oxygen-16 intermediate between the ground state and that at 5·9 MeV. have not been observed ; the absence of the latter possibility is consistent with the absence of any evidence for an excited state of O¹⁶ below 5·9 MeV.