Precision Measurement of the Neutral Pion Lifetime

As the lightest particle in the hadron spectrum, the $\pi^0$ meson plays an important role in understanding the fundamental symmetries of QCD at low-energy. The $\pi^0\rightarrow\gamma\gamma$ decay offers a key test of the QCD predictions based on the chiral anomaly and spontaneous chiral symmetry breaking. The theoretical calculations over the last decade have reached the precision of 1\% in the $\pi^0$ radiative decay width. The experimental measurement of this parameter with a comparable accuracy will be an important test of QCD. The PrimEx collaboration at Jefferson Lab developed and performed two experiments to measure the $\pi^0$ decay width via the Primakoff effect. The published result from the first experiment (PrimEx-I) has achieved the accuracy of 2.8\% in the total uncertainty. The second experiment (PrimEx-II) was carried out with a goal of 1.4\% precision. The preliminary results from the PrimEx-II experiment will be presented.