Coherent Primakoff effect: Pion creation in aligned crystals

Pion creation via the Primakoff effect is normally associated with the electric fields of single atoms. However, in special cases when pions are produced by very high-energy photons aligned with a crystal axis, the crystal structure can influence the production of pions. Resonant peaks in the pion-creation rate, as a function of the incident photon energy, should occur when the momentum transfer in the alignment direction equals a reciprocal-lattice vector of the crystal. Numerical results presented for the example of a diamond crystal show that this coherent Primakoff effect could be observed with present-day accelerator technology.