Compton Scattering Concept Question

[godtripp]

Hi,

I had an issue with compton scattering that I never received a satisfactory answer for. My issue was that after the collision, there exists a y component of momentum... but all diagrams of the compton effect align the axis center to center from the photon to the electron and on top of that each are dimensionless point particles.

So where does this y-component come from? Does the wave nature of the photon give the particle some y component of momentum or is it all in the x direction?

Hope i was clear enough...thanks in advance

 

[lightarrow]

An electron and a photon are not point particles. If they were, the classical description would be eneough, instead you know that QM is required.
Also note that the concept "being a point particle" depends on the kind and energy of the interaction too.

 

[kloptok]

If I understand you correctly you wonder why there can be a y-component of the momentum after the collision when the incident photon only has momentum in the x-direction.

The answer is that the total momentum in the y-direction after the collision is the same as before, zero. The momenta of the electron and the photon together add up to zero after the collision. This is essentialy analogous to one billiard ball hitting another - the two balls may go off in different directions (i.e. not straight forward) after the collision even though the incoming ball only travels in the 'straight forward'-direction. Was that answer to your question?

Also, as far as we know today, the electron is point-like and has no internal structure (of course this might change with future theories). The photon on the other hand is a different story. It shows a so called wave-particle duality, behaving both as a particle and a wave.

 

[godtripp]

Thanks for your answers guys!

 

[lightarrow]

Also, as far as we know today, the electron is point-like and has no internal structure (of course this might change with future theories). The photon on the other hand is a different story. It shows a so called wave-particle duality, behaving both as a particle and a wave.

Only the photon has wave-particle duality?

 

[kloptok]

Only the photon has wave-particle duality?

Dang, you got me! The thing was that I got the impression that the tread opener only thought of the photon as a point particle. But sure, the electron, as every particle, shows particle as well as wave behavior.