Differential cross section for pi -p--> gamma n from 427 to 625 MeV/c.

Abstract

Differential cross sections for ${\ensuremath{\pi}}^{\ensuremath{-}}p\ensuremath{\rightarrow}\ensuremath{\gamma}n$ have been determined from 427 to 625 MeV/c, mainly at 90\ifmmode^\circ\else\textdegree\fi{} and 110\ifmmode^\circ\else\textdegree\fi{} c.m. The data were obtained by combining measurements of the Panofsky ratio in flight with known charge-exchange cross sections. The results are compared with $\ensuremath{\gamma}n\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ensuremath{-}}p$ data derived from $\ensuremath{\gamma}d$ experiments; the difference is typically 30%. The radiative decay amplitudes of neutral $\ensuremath{\pi}N$ resonances are therefore uncertain by at least 30%.