In the expectation that at least one low-energy transition from the fourth excited state of ${\mathrm{O}}^{16}$ may compete to an observable extent with the 7.11-Mev ground-state transition, a search was made for the 0.97 Mev ($1^{-}$ → $3^{-}$) and the 1.05 Mev ($1^{-}$ → $0^{+}$) gamma rays. Limiting values, $\frac{I\left(7.11\right)\mathrm{}}{I\left(0.97\right)\mathrm{}}\gtrsim 200$ and $\frac{I\left(7.11\right)\mathrm{}}{I\left(1.05\right)\mathrm{}}\gtrsim 370$, were found for the branching ratios.

• Received 29 July 1959

DOI:https://doi.org/10.1103/PhysRev.116.1578