What happens when a photon hits and antiparticle?

[stone1]

This is probably a crazy question, but what happens to a photon when it hits an antiparticle? Say the same type of antiparticle that Hawking uses to derive his Hawking radiation. Does the photon disappear? Is its energy/frequency reduced?

 

[haael]

Exactly the same happens, as if a photon hit a "normal" particle. There is no fundamental distinction between normal and anti particles, the classification is arbitrary.

Hawking did not postulate a specific kind of particles in his radiation. Any species will do.