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 an found to be equal to within 1.2 x 10(-5) (80% confidence). This is a two orders of magn itude improvement compared to traditional detailed balance studies of time reversal, and represents the most precise test of PC TRNI in a dy namical process, to our knowledge.