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Homework Help: Alpha decay short half lives correspond to large disintegration energies

  1. May 28, 2009 #1
    1. The problem statement, all variables and given/known data

    i) Explain why in alpha decay short half lives correspond to large disintegration energies.

    ii) Determine the energy release during the alpha decay of 238U to 234Th. The mass of 238U is 238.0508mu, the mass of 234Th is 234.0436mu, and the mass of 4He is 4.0026mu.

    2. Relevant equations

    None Given

    3. The attempt at a solution

    I haven't seen an example of this in my course book, so I have more ideas than attempts at a solution.

    Would I be right in right in finding the mass defect in U, Th and He, and then subtracting U's mass defect from Th's and He's, mass defect.

    Once I have that I would use E=mc2, to calculate the energy released.

    But this seems quite long and drawn out is there another method to calculate this, is the method even right?
  2. jcsd
  3. May 28, 2009 #2


    User Avatar

    You have the right idea for ii). What you mention is essentially conservation of relativistic energy, and it doesn't get much simpler than that.

    A partial answer to i) would be to consider the conditions under which the probability of tunneling out of a potential barrier increases, and see how that is relevant to alpha decay.
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