Parity nonconservation in Pd-106 and Pd-108 neutron - art. no. 055503

Parity nonconservation (PNC) has been studied in the neutron p-wave resonan ces of Pd-106 and Pd-108 in the energy range of 20 to 2000 eV. Longitudinal asymmetries in p-wave capture cross sections are measured using longitudin ally polarized neutrons incident on similar to 20-g metal-powder targets at LANSCE. A CsI gamma-ray detector array measures capture cross section asym metries as a function of neutron energy which is determined by the neutron time-of-flight method. A total of 21 p-wave resonances in Pd-106 and 21 p-w ave resonances in Pd-108 were studied. One statistically significant PNC ef fect was observed in Pd-106, and no effects were observed in Pd-108. For Pd -106 a weak spreading width of T-w = 34(-28)(+47) x 10(-7) eV was obtained. For Pd-108 an upper limit on the weak spreading width of Gamma(w) <12x10(- 7) eV was determined at the 68% confidence level. [S0556-2813(99)05311-X].