π0Photoproduction from Hydrogen with Linearly Polarized Photons

The asymmetry in the process $\gamma +p\to {\pi }^0+p$ with polarized photons has been measured at 6 GeV for momentum transfers from $t=-0.4\mathrm{} {\left(\frac{\mathrm{GeV}}{c}\right)}^2$ to $t=-1.1\mathrm{} {\left(\frac{\mathrm{GeV}}{c}\right)}^2$, using coherent bremsstrahlung from a diamond crystal. A coincidence was made between the recoil proton in a $1.6-\frac{\mathrm{GeV}}{c}$ spectrometer and one of the ${\pi }^0$ decay photons in a Lucite shower counter. The measured asymmetry $\frac{({\sigma }_{\perp }-{\sigma }_{\parallel })}{({\sigma }_{\perp }+{\sigma }_{\parallel })}$ is consistent with strongly dominant natural parity exchange in the $t$ channel.