# Photon scattering with a moving electron

1. Sep 27, 2007

### wakko101

Hello,

The problem I have is trying to derive a formula for the compton equation, but instead of having the electron at rest, it is moving in the same direction as the incident photon. I've tried deriving it in the same manner as deriving it for an electron at rest (ie. I've simply made the change that the initial momentum and energy of the electron is no longer 0, with electron initial and final energies being of the form E=sqrt(m^2c^4 + p^2c^2)), but it seems to me that doing so results in too many extra terms that don't cancel out.

Is there something I'm missing here?

Thanks,
W. =)

2. Sep 27, 2007

### genneth

Best to do the calculation in the frame where the electron is initially at rest, so that you can use the Compton scattering formula. Then transform to the original frame. Or, if you're comfortable with the derivation of the Compton scattering formula, just do the usual transform to the zero-momentum frame where things are easy, then back out.

3. May 20, 2009

### botee

Thanks for your post, I messed a lot with this problem trying to solve it in the rest-frame of earth.

4. Sep 21, 2009

### Narayanan.S

Hi,
I think Thomson and Kleinn -Nishina scattering formulas appllies at lower and higher velocities respectively-see WIKI
Shankar