Delta Production Via Gammap-!Deltapi By Linearly Polarized Photons At 2.8 Gev And 4.7 Gev

The production of $\ensuremath{\Delta}(1236)$ by linearly polarized photons at 2.8 and 4.7 GeV was studied using a hydrogen bubble chamber. At 2.8 GeV the cross sections for $\ensuremath{\gamma}p\ensuremath{\rightarrow}{\ensuremath{\Delta}}^{++}{\ensuremath{\pi}}^{\ensuremath{-}}(\ensuremath{\gamma}p\ensuremath{\rightarrow}{\ensuremath{\Delta}}^{0}{\ensuremath{\pi}}^{+},{\ensuremath{\Delta}}^{0}\ensuremath{\rightarrow}p{\ensuremath{\pi}}^{\ensuremath{-}})$ were found to be 3.7 \ifmmode\pm\else\textpm\fi{} 0.4 \ensuremath{\mu}b (0.5 \ifmmode\pm\else\textpm\fi{} 0.2 \ensuremath{\mu}b); at 4.7 GeV, 1.0 \ifmmode\pm\else\textpm\fi{} 0.1 \ensuremath{\mu}b (0.16 \ifmmode\pm\else\textpm\fi{} 0.09 \ensuremath{\mu}b). Measurement of the parity asymmetry, ${P}_{\ensuremath{\sigma}}$, for ${\ensuremath{\Delta}}^{++}$ production with $|t|l0.5$ Ge${\mathrm{V}}^{2}$ yielded the values -0.27 \ifmmode\pm\else\textpm\fi{} 0.12 and -0.53 \ifmmode\pm\else\textpm\fi{} 0.15 at 2.8 and 4.7 GeV, respectively, whereas pure one-pion exchange would lead to ${P}_{\ensuremath{\sigma}}=\ensuremath{-}1$.