Coherent π-photoproduction from atomic nuclei

Differential and total cross sections for coherent π-photoproduction from C, Ca, Nb and Pb targets have been measured throughout the region of the ∆(1232)resonance. The experiments were performed with the TAPS-detector at the Mainz accelerator MAMI. The characteristic proportionality of the cross section to the square of the atomic mass number and to the nuclear mass form factor is clearly demonstrated. The data allow for the first time detailed tests of model predictions for this reaction. The comparison of the data to model predictions shows that the ∆nucleus interaction saturates: it is described for heavy nuclei with the same potential parameters as for He.