Calculate Thresholds for Pair/Triplet Production

[roadracerex]

I have a question I am working on for which I need some help.

"Using E^2 - p^2c^2 = invariant, calculate the thresholds for pair production and triplet production."

This is what I have for pair production:

Pair Production
E^2 – p^2c^2 = invariant
therefore, E > pc, for each electron produced, where E is the photon energy hv
E > 2[m0 v c (excess KE of electron) + m0 c^2 (rest mass of an electron)] = 2 m0 c^2 , since v = 0 for minimum photon energy
E > (2)(9.1E-31 kg)(2.998E8 m/s)2
E > 1.636E-13 J / 1.602E-13 J/MeV
E > 1.02 MeV

I am stuck on the triplet production. I found one reference that has the KE transferred to the stationary electron with the excess photon momentum = me-c^2, m sub e-

Any help or critique would be appreciated. Thanks.

 

[malawi_glenn]

what have you tried? It is hard to give you critique when don't show what you have tried.

 

[roadracerex]

I was speaking of critiquing pair production and maybe and idea where to start on the triplet. I think I will start on conservation of energy and post tonight.

Thanks.