The Collaborative International Dictionary of English v.0.48:

Pair production \Pair" pro*duc"tion\ (Physics)
   The simultaneous creation of a particle and its antiparticle,
   such as an electron and positron, from a photon; -- usually
   due to its interaction with the strong field near a nucleus.
   [PJC]

WordNet (r) 3.0 (2006):

pair production
    n 1: the transformation of a gamma-ray photon into an electron
         and a positron when the photon passes close to an atomic
         nucleus [syn: pair production, pair creation, pair
         formation]