Primakoff effect (after Henry Primakoff) is the resonant production of neutral pseudoscalar mesons by high-energy photons interacting with an atomic nucleus. It can be viewed as the reverse process of the decay of the meson into two photons.
Primakoff effect has been used for the measurement of the decay width of neutral mesons.[1]
Primakoff effect also could take place in stars, and be a production mechanism of hypothetical particles, such as the axion.
The Primakoff effect is predicted to lead to optical properties of the vacuum state in the presence of a strong magnetic field.[2]