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babblingsia
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Homework Statement
To show that the minimum energy a photon must have to create an electron-positron pair in the presence of a stationary nucleus of mass M is 2mc^2[1 + (m/M)], m is the electron rest mass.
Homework Equations
Conservation of energy and momentum.Also the minimum energy a photon should have is 1.02MeV to form an electron and a positron ( won't be needing the figures here though)
The Attempt at a Solution
I tried doing it in the center of mass frame ( coz the CM frame happens to give the minimum energy) but I'm getting nowhere. Should I be using the lorentz invariance E^2 - p^2c^2 in CM and lab frame?