What is the threshold energy below which pair production cannot occur?

Pair production is a phenomenon that occurs when a photon interacts with a strong electromagnetic field, typically near a nucleus, resulting in the creation of a particle-antiparticle pair, such as an electron and a positron. For pair production to take place, the photon must have energy that meets or exceeds a certain threshold.

The threshold energy necessary for pair production is significantly influenced by the mass-energy equivalence principle defined by Einstein's equation, (E = mc^2). The mass of an electron (or positron) is approximately 0.511 MeV. Therefore, to produce both an electron and a positron, the minimum energy required is double the rest mass energy of an electron, which is:

[

2 \times 0.511 , \text{MeV} = 1.022 , \text{MeV}

]

This means that for pair production to occur, the energy of the incident photon must surpass this threshold of 1.022 MeV. Since photons do not produce particles with less than this combined energy, it can be stated that below 1 MeV, pair production is not possible.

While the selection of 2 MeV as an option is significant, it serves to further