Differential cross sections ofπ−p→γnfor 317, 452, and 491MeVcincident pion momentum

The differential cross sections of ${\pi }^{-}p\to \gamma n$ at center-of-mass energy $\tilde{E}=1363\mathrm{}$, 1337, and 1245 MeV are presented. The angular distributions are compared with recent $\gamma n\to {\pi }^{-}p$ experiments. Though the cross sections for ${\pi }^{-}p\to \gamma n$ are somewhat lower than those for the inverse reaction, when all uncertainties are considered, we find that our data are in acceptable agreement at all three energies with the inverse reaction determined from $\frac{{\pi }^{-}}{{\pi }^{+}}$ ratio measurements, in support of time-reversal invariance. The agreement with bubble-chamber measurements at $\tilde{E}=1363\mathrm{}$ and 1337 MeV is less satisfactory. The isotensor dip test applied to our data is inconclusive. Our measurements are compared with many multipole analyses, disagreeing with most, in particular with pure fixed- $t$ dispersion relation calculations. We find no evidence, in the sense suggested by Donnachie, for the classification of the $P_{11}\mathrm{}\left(1470\right)\mathrm{}$ resonance in an SU(3) antidecuplet. The data are consistent with a small radiative decay of the $P_{11}\mathrm{}\left(1470\right)\mathrm{}$ resonance, as predicted by quark models.