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Multiple compton scattering

  1. Mar 25, 2013 #1
    I'm testing my faith in the photon. I understand that energy levels are quantized, and I understand that the EM field carries momentum. I want to make sure the idea of a photon is necessary to intuitively understand the observations.

    I am focused on compton scattering of a photon and an electron. The ideal experiment has a single electron suspended in a vacuum chamber. A laser pulse is shot across the chamber and the electron, if scattered, is detected when it impacts the wall of the chamber. Its momentum is recorded. For simplicity let's just say we measure the electrons scattered in the forward direction.

    The experiment will measure electrons having momentum consistent with having collided with a particle of momentum h / lambda where lambda is the central frequency of the laser pulse. Ergo, photon.

    I am wondering: if one turns up the laser intensity, does one sometimes observe an electron momentum consistent with having scattered off two or more photons? In other words, in the momentum distribution of the electrons, is there not only the first peak, but additional peaks higher order in the laser intensity (with decreasing spacing of course)? Or does something happen in QED wherein after the electron is entangled with the field after the first scattering, it does not undergo any additional scatterings? I do not know QED.

    Thanks for your time!

  2. jcsd
  3. Mar 29, 2013 #2
    Actually, this paper says the electron only scatters once!


    However I suspect that the paper is saying that the multiple scattering probability is very close to zero due to the fact that the electron absorbs a lot of the photon energy, but not exactly zero. Bottom of page 226 to 227:

    "Just in the first scattering event an electron transfers all its energy to a gamma-ray quantum and becomes inactive"

    And first paragraph of section 3.2: "It has already been mentioned that an electron... in reality interacts with a field photon only once, transferring practically all its energy to the latter"

    Not very particle-like.

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