Parity violation in p-wave neutron resonances

Parity violation in p-wave neutron resonances has been studied by measuring the cross section longitudinal asymmetries at neutron energies up to 300-2000 eV depending on the target. The measurements were performed by the TRIPLE collaboration using the polarization setup at the pulsed spallation neutron source of the Los Alamos Neutron Science Center. Parity violations were observed in 75 resonances of Br, Rh, Pd, Ag, Sn, In, Sb, I, Cs, Xe, La, U, and Th. Statistical methods were developed to determine the weak interaction rms matrix elements and the corresponding spreading widths Gamma(w). The average value of Gamma(w) is about 1.8 x 10(-7) eV. The individual weak spreading widths are consistent with a constant or slowly varying mass dependence, but there is evidence for local fluctuations.