TEST OF PARITY-CONSERVING TIME-REVERSAL INVARIANCE USING POLARIZED NEUTRONS AND NUCLEAR-SPIN ALIGNED HOLMIUM

A test of parity-conserving, time-reversal noninvariance (PC TRNI) has been performed in 5.9 MeV polarized neutron transmission through nucl ear spin aligned holmium. The experiment searches for the T-violating fivefold correlation via a double modulation technique-flipping the ne utron spin while rotating the alignment axis of the holmium. Relative cross sections for spin-up and spin-down neutrons are found to be equa l to within 1.2 x 10(-5) (80% confidence). This is a 2 orders of magni tude improvement compared to traditional detailed balance studies of t ime reversal, and represents the most precise test of PC TRNI in a dyn amical process.