The electron-positron pair?

Question

A detector shows evidence of the creation of an electron-positron pair. If the tracks of the particles indicate that each one has an energy of 0.26 MeV, what is the energy of the photon that created the two particles? in MeV

Answer 1

The rest mass of an electron (and a positron) is equivalent to 0.511 MeV (thanks to the E=mc^2), so in order to create a pair, the photon needs to bring 1.022 MeV. Plus, the resulting pair members each have an energy of 0.26 MeV, for an additional 0.52 MeV. So the photon had an energy of about 1.542 MeV.

Answer 2

Probably 0.52 MeV since I thought that a photon was an electron and a positron.

Snow Man