The radiation properties of the beta-emitting nuclides ${\mathrm{Si}}^{32}$ and ${\mathrm{Mg}}^{28}$ are described, ${\mathrm{Si}}^{32}$ was found to have a maximum probable half-life of 710 years, emitting beta-particles of $E_{max}\sim 100$ kev. Absence of gamma radiation with this nuclide is indicated.

• Received 2 April 1953

DOI:https://doi.org/10.1103/PhysRev.91.642