Compton Scattering: Determining the Energy of a Scattered Gamma Ray

[ChrisWM]

Homework Statement

A 0.662 MeV gamma ray Compton scatters from an electron at an angle of 60°. What is the energy of the scattered gamma ray? (Gamma rays are photons and are treated identically to x-rays in the analysis of Compton scattering.)

Relevant Equations

E(gamma prime)= E(gamma)/(1+(E(gamma)/(mc^2)(1-cos(theta))) ?

I'm unsure of how to proceed here. Would I use the equation

E(gamma prime)= E(gamma)/(1+(E(gamma)/(mc^2)(1-cos(theta))) ?

Also, do I keep the .662 Mev as is or do I convert to joules?

 

[PeroK]

Homework Statement:: A 0.662 MeV gamma ray Compton scatters from an electron at an angle of 60°. What is the energy of the scattered gamma ray? (Gamma rays are photons and are treated identically to x-rays in the analysis of Compton scattering.)
Relevant Equations:: E(gamma prime)= E(gamma)/(1+(E(gamma)/(mc^2)(1-cos(theta))) ?

I'm unsure of how to proceed here. Would I use the equation

E(gamma prime)= E(gamma)/(1+(E(gamma)/(mc^2)(1-cos(theta))) ?

Also, do I keep the .662 Mev as is or do I convert to joules?

If you already have an equation for the change in energy, then why not use it?

Definitely use $MeV$. Note that $\frac{E}{mc^2}$ is dimensionless. If you have $E$ in $MeV$, then you need $m$ in $MeV/c^2$. Which is much simpler than converting everything to SI units in this case.