High statistics study of the reaction $\pi^{-}p \rightarrow \pi^{-} \pi^{+}n$ at 17 GeV/c - the $(\pi^{+} \pi^{-})$ mass interval of the $\rho$ meson

A sample of 318000 events of the reaction pi /sup -/p to pi /sup -/ pi /sup +/n at 17.2 GeV/c with 94000 events in the mass interval of the rho meson (0.71<M( pi /sup +/ pi /sup -/)<0.83 GeV/c/sup 2/) has been measured in a spark-chamber experiment. For these latter events the pi /sup +/ pi /sup -/ decay angular distribution parametrized in spherical harmonic moments has been studied as a function of t, the four-momentum transfer squared between p and n. At high mod t mod the rho is produced in an almost pure t-channel helicity one state with around 80% natural parity exchange. A comparison of the data with the absolute predictions of the simple absorption model parametrization of Williams shows good agreement, but only in the range -t<0.06 (GeV)/sup 2/. (7 refs).