Precision Measurement of $\pi^{0}$ Lifetime via the Primakoff Effect

As the lightest particle in the hadron spectrum, $\pi^{0}$ plays an important role in understanding the fundamental symmetries of QCD at low-energy. The $\pi^{0} \to \gamma \gamma$ decay width 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 1{\%} precision in the decay amplitude of the $\pi^{0}$ into two photons. The experimental measurement of this parameter with a comparable precision will be an important test of QCD. The PrimEx collaboration at Jefferson Lab has developed and performed experiments to measure the $\pi^{0}$ radiative decay width via the Primakoff effect. The published result from the first experiment (PrimEx-I) has a 2.8{\%} total uncertainty. The second experiment (PrimEx-II) was carried out with the final goal of 1.4{\%} precision. The preliminary result of PrimEx-II will be presented.