PRECISE SEARCH FOR VIOLATION OF TIME-REVERSAL INVARIANCE IN NUCLEAR DECAY SUS IN GLOW-TEMPERATURE NUCLEAR POLARIZATION

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Time-reversal invariance in the gamma transitions were investigated by observing the angular distribution of the linear polarization of the mixed (E2, M1) gamma transitions in ^<192>Pt from a source of ^<192>IrFe polarized at a low temperature of 9.3 (1) mK.As the polarimeters, four thin disk-type (two 44mmPHIx15mm, two 51mmPHIx20mm) detectors were used. The linear polarization could be detected in single gamma-ray measurements by these detectors. By this method it is possible to measure the linear polarization with high energy resolution without troubles of coincidence circuits. They were placed at the symmetric positions each other and at the angles of 54.7 and 125.3 degree with respect to the spin direction. The asymmetries of the 308-, 484- and 604-ke Vgamma rays were measured. Values of phase angles of sin (eta+xi) were obtained to be 1(14) x10^<-3>,0 (30) x10^<-3> and 2.1 (53) x10^<-3> for the 308-, 484- and 604-ke Vgamma transitions, respectively. These results are consistent with time reversal invariance.In order to improve the polarization sensitivity we employed more thinner detectors (two 51mmPHIx7mm) . The measurements were performed for about 35 days. Now the result of the value ofsin (eta+xi) for the 604-keV transition were tentatively obtainde ; -26 (25) x10^<-4>, -80 (74) x10^<-4>, -30 (28) x10^<-4>,90 (94) x10^<-4> for the detector Nos.1-4 respectively. Detailed analyzes are now in progress.