Radioactive phosphorus has been obtained by an $n$, $p$ reaction on sulfur which had been electromagnetically enriched in ${\mathrm{S}}^{33}$. The beta spectrum of this phosphorus showed an increase in the low energy beta group approximately proportional to the isotopic enrichment. This confirms the previous identification of this activity with ${\mathrm{P}}^{33}$. The maximum beta energy was determined from several Kurie plots and found to be 0.249±0.002 Mev. The half-life was found to be 24.4±0.2 days. The spectrum appears to have an allowed shape as is expected from theoretical considerations.

• Received 13 August 1953

DOI:https://doi.org/10.1103/PhysRev.94.369