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Homework Help: Charge non-conservation

  1. Jul 22, 2008 #1
    1. The problem statement, all variables and given/known data
    The problem is:
    A proton collides with a Helium nucleus. What is the minimum lab kinetic energy needed to produce an anti-proton?

    2. Relevant equations

    3. The attempt at a solution
    I suppose that helium nucleus is at rest in the lab frame.
    I'm wondering about the final particles of this reaction.
    Originally, I guess the result is a proton, an anti-proton and the helium nucleus, but in this way, the charge is not conserved. So I guess the final particles are two protons , an anti-proton and helium nucleus, but my friend told me that the standard answer in the text is that the final state is with one proton, one anti-proton and one helium nucleus.
    So, the charge can be not conserved in a reaction?
    (This means that the interaction is not electromagnetic?)

    Thanks for all ideas.
  2. jcsd
  3. Jul 22, 2008 #2


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    Science Advisor
    Homework Helper

    Charge is certainly conserved and your friend is wrong. Your guess is correct. Notice you also need to conserve baryon number. Producing a proton, anti-proton pair is really your only choice.
  4. Jul 23, 2008 #3
    Yeah, the energy for particle-antiparticle production is always [tex]2mc^2[/tex], where m is the mass of one of the particles.
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