Inverse pion photoproduction in the vicinity of thep33(1232)resonance and a test of time-reversal invariance

Differential cross-section measurements are presented for ${\pi }^{-}p\to \gamma n$ at five energies around the $p_{33}\mathrm{}\left(1232\right)\mathrm{}$ resonance. A detailed comparison is made with $\gamma n\to {\pi }^{-}p$ deduced from $\gamma d$ experiments. In general, the results are in support of detailed balance. Using the Christ-Lee-Donnachie-Shaw model, our new data indicate that the $T$-violating phase in the isovector part of the $M_{1^{+}}$ multipole is less than 2°, which is a very sensitive test of time-reversal invariance. No evidence is found for a possible isotensor component of the electromagnetic current. Our data are compared to various multipole analyses. In general, the agreement is poor.