If parity is strictly conserved, the gamma rays emitted following the bombardment of unpolarized target nuclei by unpolarized projectiles can show no circular polarization. We look for such polarization, using an analyzer of magnetized iron, in the 2.14-Mev gamma ray from the first excited state of ${\mathrm{B}}^{11}$ formed by ${\mathrm{B}}^{11}(p, p^{\prime }){\mathrm{B}}^{11*}$ and in the 7.12-Mev gamma ray from the fourth excited state of ${\mathrm{O}}^{16}$ formed in ${\mathrm{F}}^{19}(p, \alpha ){\mathrm{O}}^{16*}$. We expect this polarization to be of order $\mathcal{R}\mathfrak{F}$, where $\mathfrak{F}$ is the amplitude of the parity-nonconserving part of the relevant wave functions and $\mathcal{R}$ is a matrix element factor. We find that the intensity of circular polarization in the first case is less than 2.0×${10}^{-3\mathrm{}}$ and in the second case 2.0×${10}^{-3\mathrm{}}$. These figures yield ${\mathfrak{F}}^2\lesssim 1\times {10}^{-7\mathrm{}}$ and ${\mathfrak{F}}^2\lesssim 3\times {10}^{-8\mathrm{}}$ respectively.

• Received 22 October 1957

DOI:https://doi.org/10.1103/PhysRev.109.1610