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Homework Help: Radiation decay

  1. Mar 6, 2016 #1
    1. If I throw sixty different dice (compared to an atomic nucleus) and each dice that gets a 3 is disintegrated and disappear before the next roll. Altogether I make ten roll, where each roll corresponds to one day. The result is illustrated in a graph: http://imgur.com/TbXF4mf click on the picture to see. X = time in days, Y = decays under a day These questions must be answered: a) How can I read and calculate the half-life through my function expression? b) What is the function expression? c) the relationship between nuclei activity d) The difference between a nucleus and dice?

    2. No equations given.

    3. The half-life must surely be somewhere between the third and fourth day (throw). But how can I calculate it exactly by reading? Functional expression is well in my graph: 15.19 * e ^ -0,25x. This is indeed a exponentiellfunktion, if I understand correctly? How can I get out activity between nuclei I have not decay constant? The last question I do not understand at all ..
    Last edited by a moderator: Mar 6, 2016
  2. jcsd
  3. Mar 6, 2016 #2


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    I believe the usual approach is maximum likelihood. I.e., what value of the parameter makes the observations most likely?
    See e.g. https://en.wikipedia.org/wiki/Exponential_distribution.

    Not sure that I understand the model, though.
    Are you saying 60 dice represent (the neutrons in?) one nucleus? If so, once one has decayed everything changes. So I would have thought 60 dice represented 60 nuclei. Presumably, as they decay, you roll fewer dice each day.
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