Test of Parity Conservation inN−NScattering

The parity-nonconserving double-scattering parameter $a_k$ was measured at five laboratory scattering angles using a longitudinally polarized 210-MeV proton beam with targets of carbon and polyethylene. An impulse approximation was used to relate the proton-carbon scattering to nucleon-nucleon scattering. Beam polarization was reversed by a solenoidal magnetic field, and the asymmetry was taken between the counting rates observed for the two senses of polarization. Measured values of $a_k$ are consistent with zero and suggest that, barring cancellation among terms, the ratio of parity-nonconserving amplitudes to parity-conserving amplitudes is less than 5 × ${10}^{-3\mathrm{}}$. Assuming time-reversal invariance, the parity nonconserving mixings of the ${}_{}{}^1{}_{}{}^{}S_0^{}{}_{}{}^{}$ and ${}_{}{}^3{}_{}{}^{}P_0^{}{}_{}{}^{}$ states and of the ${}_{}{}^3{}_{}{}^{}S_1^{}{}_{}{}^{}$ and ${}_{}{}^1{}_{}{}^{}P_1^{}{}_{}{}^{}$ states are, respectively, less than 10% and 3% of their maximum possible values.