- #1

RoadDog

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- TL;DR Summary
- I'm trying to reconcile the differential cross sections for Compton recoil electron energies with that of photons scattered into a certain solid angle

Hi folks,

My understanding of the Compton Effect is that maximum energy transfer to the electron takes place when the photon scattering angle is 180 degrees.

For the following please reference Evans "The Atomic Nucleus" :

https://library.psfc.mit.edu/catalog/online_pubs/books/evans_atomic_nucleus.pdf

Page 683 (697 of the PDF): Eq. 2.8 and Fig 2.3 (polar plot) show that for photons of higher incident energy, the differential cross section shows a tendency to forward scatter (photon scattering angle closer to zero degrees)

Therefore, it seems that high-energy photons are more likely to transfer *little* energy to electrons.

Now Eq. 5.2 and Fig 5.1 for the energy spectrum of recoil electrons show that the differential cross section for scattering electrons into a certain recoil energy interval is highest at the Compton Edge (i.e. 180 degree scattering)

These two differential cross sections seem contradictory to me. dsigma/dOmega tells me that high-energy photons are more likely to scatter at zero degrees but dsigma/dT tells me that scattering will most likely give recoil-electron energies at the Compton edge, which implies a photon scattering angle of 180 degrees. What am I missing here? T

Thanks in advance for your help!

My understanding of the Compton Effect is that maximum energy transfer to the electron takes place when the photon scattering angle is 180 degrees.

For the following please reference Evans "The Atomic Nucleus" :

https://library.psfc.mit.edu/catalog/online_pubs/books/evans_atomic_nucleus.pdf

Page 683 (697 of the PDF): Eq. 2.8 and Fig 2.3 (polar plot) show that for photons of higher incident energy, the differential cross section shows a tendency to forward scatter (photon scattering angle closer to zero degrees)

Therefore, it seems that high-energy photons are more likely to transfer *little* energy to electrons.

Now Eq. 5.2 and Fig 5.1 for the energy spectrum of recoil electrons show that the differential cross section for scattering electrons into a certain recoil energy interval is highest at the Compton Edge (i.e. 180 degree scattering)

These two differential cross sections seem contradictory to me. dsigma/dOmega tells me that high-energy photons are more likely to scatter at zero degrees but dsigma/dT tells me that scattering will most likely give recoil-electron energies at the Compton edge, which implies a photon scattering angle of 180 degrees. What am I missing here? T

Thanks in advance for your help!