Question

A 3.0 MeV photon interacts with a lead nucleus in empty space. What would be the Kinetic Energy of the electron and positron pair?

(a) 2.01 MeV

(b) 1.5 MeV

(c) 1.45 MeV

(d) Electron-Positron pair won’t be created

The question was asked in an international level competition.

I'd like to ask this question from Pair Productions in division Quantum Physics of Engineering Physics I

Answer 1

Right choice is (d) Electron-Positron pair won’t be created

The best I can explain: It is given in the question that the photon strikes the nucleus in empty space. In empty space, the law of conservation of energy and momentum does not take place. Thus, pair-production won’t occur.