When a gamma ray $($a high$-$energy photon$)$ collides with a heavy atomic nucleus, it can produce a muon $()$antimuon $(+)$ pair. Determine the minimum energy $($in MeV$)$ that a gamma ray must have in order for this pair$-$production event to occur. $($The masses of a muon and an antimuon are both $1\mathrm{.}881028$ kg$.)$