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We give an overview of the physics motivation and evolution of the neutralpion photoproduction measurements in the threshold region conducted in the A2collaboration at MAMI. The latest two experiments have been performed with thealmost 4-pi Crystal Ball detector. The first was with a linearly polarizedphoton beam and unpolarized liquid-hydrogen target. The data analysis is nowcomplete and the linearly polarized beam asymmetry along with differentialcross sections provide the most stringent test to date of the predictions ofChiral Perturbation Theory and its energy region of convergence. More recentlya measurement was performed using both circularly polarized photons and atransversely polarized butanol frozen-spin target, with the goal of extractingboth the target and beam-target asymmetries. From these we intend to extractpi-N scattering sensitive information for the first time in photo-pionreactions. This will be used to test isospin conservation and further testdynamics of chiral symmetry breaking in QCD as calculated at low energies byChiral Perturbation Theory.

Neutral Pion Production in the Threshold Region