Test of Time-Reversal Invariance via aβ−γ−γAngular Correlation inRh106-Pd106

A measurement of the relative phase angle $\eta$ between the $E2\mathrm{}$ and $M1\mathrm{}$ reduced matrix elements in the 1.050-MeV transition of ${}_{}{}^{106}{}_{}{}^{}\mathrm{Pd}$ has been made by means of a $\beta -\gamma -\gamma$ angular correlation. Instrumental and background asymmetries in the data were carefully measured and found to be negligible. A value $sin\eta =+0.004\mathrm{}\pm 0.018$ was obtained. Time-reversal invariance requires $sin\eta \equiv 0$; thus, the present result is consistent with no violation of time-reversal invariance.