[填空题]
What minimum amount of electromagnetic energy is needed to produce anetd,l55ho lh 1 el9 3ghm 9;n wlgkqh4w 1wob-(ztectron and a positron together? A positron is a particle with the same rest mass aw1(3g9-;mbwhg49hkqn lw o tzs an electron, but has the opposite charge. (Note that electric charge is conserved in this process.) E = MeV