Parity nonconservation in neutron resonances

Experiments to observe the parity nonconserving effects in 81Br, 111Cd, 117Sn, 127I, 139La and 238U are described. The measurements were performed with a beam of polarized neutrons from the pulsed reactor IBR-30 at Dubna. A dependence of total cross sections on neutron helicity was discovered in the following resonances: 0.88 eV 81Br, 4.53 eV 111Cd, 1.33 eV 117Sn, and 0.75 eV 139La. The effect has a resonance character and is in agreement with theoretical predictions made in the framework of the model of mixing compound states. The paper contains experimental estimates for the mixing coefficients and matrix elements.