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Homework Help: Particle decays

  1. Oct 8, 2005 #1


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    I've been trying to use energy and momentum conservation in this problem but it didn't work out or I got a quadratic equation and got 3 different answers. Can anyone help me please. Here is the problem

    The Gorgon ( rest mass of 3000 MeV/c^2) decays into a photon (i.e, a particle of light) and Lexicon (rest mass of 1800 MeV/c^2).

    The Gorgon was initially at rest. The photon is emitted in the -x direction and the Lexicon is in the +x direction. Find the energy of the photon and the final velocity of the Lexicon.

    Thanks a lot
  2. jcsd
  3. Oct 8, 2005 #2


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    Staff Emeritus
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    Please show what you have done.

    Think - Conservation of energy and conservation of momentum.

    The momentum of a photon, p = E/c

    Remember there is rest energy and kinetic energy, so total energy must be conserved, and momentum.
  4. Oct 9, 2005 #3


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    I have Eg = Ep + El and the same thing for p

    also E = square root of [(pc)^2 + (mc^2)^2]

    and pc of photon will be equal -pc of elicon.

    Substitute both of the above into the conservation of energy equation. I only have one unknow which is p of photon. But then I got a quandratic equation with 3 different answers. I dunno what to do next.

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