We present a comprehensive discussion of an experiment, previously reported, to test time-reversal (T) invariance in the β decay of Ne19. The "time-reversal" coefficient D, as well as the neutrino and positron asymmetry coefficients B and A, respectively, is measured, with results as follows: D=+0.002±0.014, B=-0.90±0.13, and A=-0.039±0.002. The value of D, based on 30 000 events, is consistent with T invariance: T invariance implies D=0, since final-state corrections to D are negligible. The atomic-beam method is used to form a nuclear-spin polarized beam of Ne19 atoms in the S01 ground state. Coefficients D and B are measured by observing correlations between the positron and recoil ion F-19 (in delayed coincidence) with respect to the Ne19 spin polarization, from decays in flight. The beam terminates its flight in a cell where Ne19 atoms are captured and remain for approximately 3 sec but suffer no significant depolarization. Positrons emitted parallel and antiparallel to the spin by Ne19 decaying in the cell are counted to measure β. The results of our measurements are compared with similar observations of the A decay of polarized neutrons.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)