The possibility of searching for time-reversal symmetry violation in the scattering of epithermal neutrons from nuclei is discussed. Sources of both statistical and systematic errors are reviewed. A qualitative assessment of the size of the time reversal is made and a schematic design of an experiment to test time reversal symmetry is presented. (DWL) 10 refs., 1 fig.
The International Workshop on Time Reversal Invariance and Parity Violation in Neutron Reactions focused on the study of parity violation (PV) and time reversal invariance (TRI) in neutron physics. Emphasis was placed on measurements with polarized neutron beams and polarized targets as well as on the implication of recent theoretical developments for the future progress of this rapidly developing and increasingly important field of research.
In 1988, Bunakov proposed a test of parity (P) even time reversal (T) violation in the neighborhood of two interfering p-wave resonances of the same spin. A similar enhancement exists if a d-wave and s-wave resonance interfere. Until now, however, no suitable resonances have been located in nuclei which can be aligned, and the only tests of time reversal violation in neutron transmission have been carried out with MeV-energy neutrons. The authors estimate the deformation effect cross sections for neutron resonances in aligned [sup 165]Ho, and estimate the sensitivity of a five-fold correlation time reversal test carried out on a resonance that exhibits a deformation effect.
Experiments to test time-reversal invariance are discussed. The experiments are based on observables constructed from the momentum and spin vectors of epithermal neutrons and from the spin of an aligned or polarized target. It is shown that the proposed tests are detailed balance tests of time-reversal invariance. The status of the experiments is briefly reviewed. 14 refs., 5 figs.
I'll discuss the experiments in which parity violation has been measured in low energy neutron-nucleus scattering. The interest is two-fold: to understand how parity violation in the nucleon-nucleon (NN) interaction manifests itself in a complicated many-body system and to show that the large enhancements observed make this a good laboratory to search for violations of TRI. Further, the procedure of relating the measured parity violating asymmetries to the under-lying NN interaction will be important in order to make the same connection in violation of TRI (or in limits). First, I'll make brief comments on some relevant features of low energy neutron scattering and then review the existing measurements of parity violation. I'll try to explain, at least qualitatively, the origin of the large enhancements observed. Finally, I'll describe the TRIPLE collaboration program to study parity violation and discuss planned experiments to search for violations of TRI. 23 refs.
