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Electron beam hitting a metal plate

  1. Jun 29, 2015 #1
    So i have this simple situation where i have an electron beam with a certain kinetic energy, and i have a metal plate connected to the ground, and the electrons hit the plate, now i want to know the voltage of the current in the wire to the ground. Now i know both kinetic energy of the electrons and the current so if the energy of a current is V*I*t and the energy we can get from a certain number or electrons is N*Ke where N is the number of electrons is N and Ke is the kinetic energy , this gives us V=Ke but i dont know if that's right, so if it's wrong , what's the right answer ?
  2. jcsd
  3. Jun 29, 2015 #2


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    I would expect it to be zero because it's connected to ground

    depending on the energy of the electrons, there's a higher chance of X-rays being produced
  4. Jun 30, 2015 #3
    what if the electrons don't have enough energy to produce x-rays
  5. Jun 30, 2015 #4
    They won't produce them. But this doesn't change the answer. I thing davenn mentioned x-rays as a side aspects.
  6. Jun 30, 2015 #5


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    indeed :)

    then they just go straight to ground
  7. Jun 30, 2015 #6
    i did some research about that and i have 1 last question, can they produce gamma rays if the kinetic energy is really high or it has a limit to the energy of photon produced and the rest becomes heat, i personally think it's the second choice, but i am always wrong , so what do you think?
  8. Jun 30, 2015 #7


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    Now I'm not a particle physicist OK ( those in the field may chime in with additional info)

    putting aside astronomical sources of Gamma rays ... stars, black holes etc

    on earth, Gamma rays are produced in the natural radioactive decay process, along with Alpha and Beta particles
    would be the principle source. a secondary source is produced by firing Gamma rays at a atom where you can get an electron-positron annihilation
    which results in the release of Gamma rays
    ( I personally don't want to go deeper than that without getting out of my depth very quickly :wink: )

  9. Jun 30, 2015 #8


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    Yes, electrons fired into a stationary target are used to produce EM radiation of up to 25 MeV, if not more. Note that since this radiation isn't produced by the decay of an atomic nucleus it would probably be classified as high energy X-rays, not gamma rays. The distinction between the two is that gamma radiation is usually defined to be EM radiation produced by the decay of an atomic nucleus, regardless of the energy of the radiation. A notable exception is in astronomy, where the two are defined according to their energy.

    To quote wiki: https://en.wikipedia.org/wiki/Gamma_ray

  10. Jul 2, 2015 #9


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    Wow. This thing started out being quite simple, and has turned into a radiation-generating device!

    To the OP: you may want to look at an instrument called the Faraday Cup. And yes, you can measure the amount of charge that hit the metal plate, in principle. This instrument is used in many accelerator beamline as an alternative to the ICT (integrated charge transformer) to measure the amount of charge in a bunch. The physics of it is rather easy to follow. Of course, to make a low-noise, high time-resolution device will require a lot of other things, but the principle is the same.

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