Energy of scattering photon and emitted electron

[gruba]

Homework Statement

Photon of energy $E=0,3MeV$ is scattering at an angle $\phi=\frac{2\pi}{3}$. Calculate the energy $E'$ of scattered photon and emitted electron.

Homework Equations

-Compton effect

The Attempt at a Solution

By Compton effect, $$\frac{hc}{E'}-\frac{hc}{E}=\frac{2hc}{mc^2}\sin^2\frac{\phi}{2}\Rightarrow E'=\frac{mc^2E}{2E\sin^2\frac{\phi}{2}+mc^2}$$

What is the value of a mass $m$ of scattered photon and emitted electron?

 

[mfb]

You can look up the masses, but you should certainly know the mass of a photon, and a rough estimate for the mass of an electron. One of them wouldn't make sense in this context.