Neutron-irradiated quartz has been found to contain 14.3-day ${\mathrm{P}}^{32}$ more than two years after the end of irradiation. This is evidence for a long-lived ${\mathrm{Si}}^{32}$ formed from stable ${\mathrm{Si}}^{30}$ by the capture of two neutrons. The ratio of half-life of ${\mathrm{Si}}^{32}$, in years, to neutron capture cross section of ${\mathrm{Si}}^{31}$, in barns is 600.

• Received 24 August 1953

DOI:https://doi.org/10.1103/PhysRev.94.364