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Parity-nonconserving longitudinal analyzing powers were measured for 23 p-wave neutron resonances in ^^^Th. Seven resonances show effects of greater than 2CT 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.PACS numbers: 25.40.Ny, n.30.Er, 2L30.+y, Polarized-neutron transmission experiments show remarkable sensitivity to the presence of small symmetryviolating forces in nuclear interactions. Parity-nonconserving (PNC) analyzing powers of order of a percent or more have been observed [1-3] for /7-wave resonances in nuclei ranging from ^'Br to ^^^U. The resonances correspond to highly excited compound nuclear (CN) states-so complicated they can only be described statistically. The number of single-particle components in the wave functions is of order 7V~(l MeV)/A^ -10^-10^ where AE is the CN energy level spacing. The large enhancement of the PNC analyzing powers over the typical 10 ~^ size of weak-interaction effects is conventionally explained [4,5] by assuming that the mixing occurs between wave functions of closely spaced CN levels of the same spin / but opposite parity ± 7t. The PNC matrix elements K/y scale as l/V/V^ and the spacings scale as 1/7V, resulting in an enhancement of Jl^ in the wave-function admixture Vij/AE. The PNC analyzing power is further enhanced by the favorable ratio of ^-wave to />-wave decay amplitudes, YSJ and y^/ (see below).For some time it was not considered possible to interpret the analyzing powers in anything but a qualitative fashion due to the complexity of the wave functions involved. But recently, statistical methods [3,6-8] have been developed that relate the root-mean-square PNC matrix element M to symmetry violation in the residual shell-model effective nucleon-nucleon interaction. Thus the complexity of the CN states, which leads to the large magnification of symmetry violation, also leads to a statistical interpretation within which the observed effects can be quantified.Previous results [1-3] were generally consistent with the conventional CN statistical model. But because only five large effects had been observed, a number of questions about the mechanism of parity mixing remained. The model predicts that all pairs of / ~ ' resonances should interfere and, at some level, show nonzero PNC analyzing powers. In addition, matrix elements and neutron decay amplitudes are expected to be essentially uncorrelated because of the large number of components in the CN wave functions. Thus K/y, ysj, and /p, are taken to be statistically independent Gaussian random variables [8]. Parity-violating asymmetries are expected to be random in sign.In the present work we have studied parity-violating asymmetries for 23 p-wave resonances in ^^^Th a...

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