A test of parity-conserving, time-reversal noninvariance ͑PC TRNI͒ has been performed in 5.9 MeV polarized neutron transmission through nuclear spin aligned holmium. The experiment searches for the T-violating fivefold correlation via a double modulation technique-flipping the neutron spin while rotating the alignment axis of the holmium. Relative cross sections for spin-up and spin-down neutrons are found to be equal to within 1.2ϫ10 Ϫ5 ͑80% confidence͒. This is a two orders of magnitude improvement compared to traditional detailed balance studies of time reversal, and represents the most precise test of PC TRNI in a dynamical process, to our knowledge. ͓S0556-2813͑97͒06905-7͔
We report on polarized beam-polarized target measurements of the spin-dependent neutron-proton total cross-section differences in longitudinal and transverse geometries (Ds L and Ds T , respectively) between E n 5 and 20 MeV. Single-parameter phase-shift analyses were performed to extract the phase-shift mixing parameter´1, which characterizes the strength of the nucleon-nucleon tensor interaction at low energies. Consistent with the trend of previous determinations at E n 25 and 50 MeV, our values for´1 imply a stronger tensor force than predicted by meson-exchange nucleonnucleon potential models and nucleon-nucleon phase-shift analyses.
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