Abstract
We present a comprehensive discussion of an experiment, previously reported, to test time-reversal () invariance in the decay of . The "time-reversal" coefficient , as well as the neutrino and positron asymmetry coefficients and , respectively, is measured, with results as follows: , , and . The value of , based on 30 000 events, is consistent with invariance: invariance implies , since final-state corrections to are negligible. The atomic-beam method is used to form a nuclear-spin polarized beam of atoms in the ground state. Coefficients and are measured by observing correlations between the positron and recoil ion (in delayed coincidence) with respect to the spin polarization, from decays in flight. The beam terminates its flight in a cell where atoms are captured and remain for approximately 3 sec but suffer no significant depolarization. Positrons emitted parallel and antiparallel to the spin by decaying in the cell are counted to measure . The results of our measurements are compared with similar observations of the decay of polarized neutrons.
- Received 4 March 1969
DOI:https://doi.org/10.1103/PhysRev.184.1117
©1969 American Physical Society