Conservation of Parity in Strong Interactions

An investigation was made of the angular distribution of the gamma rays produced by the capture of slow polarized neutrons in cadmium, indium, and silver. The portion of the intensity of the transitions from the spin-one capture state of ${\mathrm{Cd}}^{114}$ to the spin-zero ground state and spin-two first excited state, which is proportional to $cos\theta$, where $\theta$ is the angle between the neutron spin and the direction of propagation of the gamma ray, was measured to be less than one part in ${10}^3$. From this result the conclusion is reached that the intensity of the odd-parity part of the neutron capture state is less than 2×${10}^{-9\mathrm{}}$ times as large as the evenparity part, and that the parity-nonconserving part of nuclear forces is less than ${10}^{-8\mathrm{}}$ times as strong as the parity-conserving part. Qualitatively similar, though weaker, conclusions were derived from the measurements on silver and indium.