Coherent Photoproduction of theη0Meson from Deuterium

The isoscalar part of the ${\eta }^0$ photoproduction amplitude near threshold has been determined by differential cross-section measurements of the coherent process $\gamma +d\to {\eta }^0+d$ from near threshold to 150 MeV above threshold. By comparison of the results with earlier measurements of $\gamma +p\to {\eta }^0+p$ and a recent measurement of $\gamma +d\to {\eta }^0+(p, n)$ it is possible to argue that the isovector part of the ${\eta }^0$ photoproduction amplitude near threshold is much smaller than the isoscalar part and is consistent with zero.