Sign correlations and parity nonconservation for neutron resonances inTh232

Parity-nonconserving longitudinal analyzing powers were measured for 23 p-wave neutron resonances in ${}_{}{}^{232}{}_{}{}^{}\mathrm{Th}$. Seven resonances show effects of greater than 2σ statistical significance (95% confidence)—the largest sample yet measured in a single nucleus. All seven analyzing powers have positive sign. Strong sign correlations are not a feature of the conventional statistical model of parity mixing between compound nuclear states. The results suggest that the mechanism of parity violation in resonance reactions is more complicated than previously assumed.