Small-angle photon scattering on complex nuclei

Photons of 3 GeV and 5 GeV were scattered on 7 different elements, ranging from Be to Au, and detected with a pair spectrometer. The angular distributions show diffractive patterns consistent with known nuclear sizes. Forward cross sections are 20–30% lower than expected from an A² dependence. This shadowing effect is qualitatively explained by photon interactions via intermediate hadronic states.