1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Compton Scattering Angle - CM FRAME

  1. Jan 9, 2015 #1
    1. The problem statement, all variables and given/known data
    Given incoming photon has energy 10Mev and scatters at angle 25 degrees, find the scattering angle in CM frame.


    fyzy40.png
    2. Relevant equations


    3. The attempt at a solution

    In lab frame, let the energy of incoming photon be ##E##. Total 4-vector would be ##P + Q = (\frac{E}{c},\frac{E}{c}) + (mc,0)##.

    Using compton scattering formulas, I solved the scattering angle of electron ##\alpha = 35 ^o##, energy of scatted electron ##E_e = 4.02 ~MeV##, energy of scattered photon ##E' = 5.47~MeV##.


    Having solved this completely in the lab frame before/after scattering, how do I proceed in CM-frame?

    In CM frame, total momentum is ##0##, so 4-vector would be ##P_{cm} + Q_{cm} = (\frac{E_{p,cm}+E_{e,cm}}{c},0)##.

    Even when I assume that in CM frame they are both scattered along the same line it doesn't help.
     
  2. jcsd
  3. Jan 10, 2015 #2

    vela

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Education Advisor

    Did you mean ##\alpha=35^\circ## or is that a typo?

    Since you know everything the lab frame, you can simply use the Lorentz transformation to find the four-vectors in the CM frame. Suppose the CM moves with speed ##\beta=v/c##. Get expressions for the three-momentum of the photon and the electron in the CM frame. As you noted, their sum should be 0, which will allow you to determine ##\beta##.
     
  4. Apr 26, 2015 #3
    Solved.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Compton Scattering Angle - CM FRAME
Loading...