Coherent production of positronium atom in crystal

The theory of coherent type B positronium atom production by high energy photon in a real (three dimensional) crystal has been developed. On the basis of the developed theory the orientation dependence of the positronium atom coherent type B photoproduction cross-section is studied. It is shown that small change of the photon energy in the vicinity of coherent peak results in change of character of the orientation dependence of coherent type B Ps photoproduction.