High energy free electron and low energy photon collision

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Discussion Overview

The discussion revolves around the collision between a high energy free electron and a low energy photon, exploring the theoretical implications, experimental feasibility, and specific phenomena such as Compton scattering.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions the possibility of a high energy free electron colliding with a low energy photon and inquires about the outcomes and laboratory replication.
  • Another participant suggests that a collision can occur and notes that the situation can be analyzed from different reference frames, asserting that nothing unusual happens in such collisions.
  • A third participant describes the Compton back-scattering phenomenon when a high energy photon collides with an electron beam, mentioning a specific energy gain formula.
  • One participant identifies the scenario as related to the Compton effect but expresses confusion regarding the equivalence of the two reference frames discussed.
  • Another participant elaborates on Compton scattering, explaining the recoil of the electron and the energy gain of the photon when changing reference frames.

Areas of Agreement / Disagreement

Participants express differing views on the equivalence of reference frames and the implications of the collisions, indicating that multiple competing perspectives remain without a clear consensus.

Contextual Notes

There are unresolved aspects regarding the assumptions made about the energy levels of the photon and electron, as well as the conditions under which the collisions are analyzed.

Khanguy
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please feel free to correct me on any of this. is it possible for a high energy free electron to collide with a low energy photon? If so, what happens? And can this be replicated in a laboratory setting?
 
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Consider an electron at rest and a high energy photon colliding. It's the same process as the one you described, though viewed from two different reference frames. So, yes, it can happen. Nothing out of the ordinary happens. Your last question depends on whether you want the experiment done in a particular frame.
 
If you shoot a laser beam at a high energy (multi-MeV or GeV) electron beam, the photon bounces back (Compton back-scatters) with an energy gain of ~4γ2. See Eq (4) in

http://www.google.com/url?sa=t&source=web&cd=1&ved=0CB4QFjAA&url=http%3A%2F%2Fwww.jlab.org%2F~cole%2FISU%2FLCS-NIM.pdf&ei=G2xxTNCeGZDksQOq3qStCw&usg=AFQjCNGH8k_elzkauWss03kprI4bGs7FqA&sig2=FszAd-Ej2dW1jRVs8PMdBA

Bob S
 
Last edited by a moderator:
this sounds like Compton effect to me. but i still don't understand why they would be the same.
 
In Compton scattering, the electron recoils, and the photon back-scatters. Each time the Lorentz frame changes from/to the lab frame to/from the electron rest frame, the photon gains energy by factor 2γ.

Bob S
 

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