Positrons from Light Nuclei

Four nuclei of the type discussed by Wigner, containing one more proton than neutron, have been produced. The nuclei, their half-lives and positron energies are: ${\mathrm{P}}^{29}$, 4.6 seconds, 3.63 Mev; $S^{31}$, 3.2 seconds, 3.85 Mev; ${\mathrm{Cl}}^{33}$, 2.4 seconds, 4.13 Mev; and ${\mathrm{A}}^{35}$, 2.2 seconds, 4.38 Mev. These energies are in excellent agreement with the calculated values and indicate that (1) the $\pi -\pi$ force is equal to the $\nu -\nu$ force plus the Coulomb repulsion, (2) the nuclear volumes are proportional to the atomic weights, and (3) the nuclear charge is distributed uniformly through the volume. The half-life-energy relation is in good agreement with the Fermi theory. Deviations are in the direction anticipated by the Gamow-Teller modification.