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Calculate how many alpha-particles from the decay will be detected

  1. Feb 15, 2008 #1
    "1 mg (0.001 g) of the isotope 239Pu is placed inside a detector. 239Pu alpha-decays with a half-life of T1/2 = 24119 yr. Calculate how many alpha-particles from the decay will be detected in 1 hour. (Assume 100% detection efficiency)."
    Could someone please show me how to do this question?

    Thanks:).
     
  2. jcsd
  3. Feb 15, 2008 #2

    malawi_glenn

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    This is Homework?

    I can give you a hint before you answer my question.

    How many 239Pu isotopes are there in 1mg ?
     
  4. Feb 16, 2008 #3
    Yes this is. I really don't know how to work that out right now, could you give me a hint?
     
  5. Feb 16, 2008 #4

    malawi_glenn

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    If it is HW then It must be posted there, do so in the future!

    So you have no idea how to work out how many atoms a certain amount of mass have? You must be joking! How can you get a HW of this kind if you have not been taught how to do that?
     
  6. Feb 16, 2008 #5
    I would have guessed you would need to use the Avogadro Constant? That would tell you how many atoms are in a mole. Would I be correct in saying that malawi_glenn?
     
  7. Feb 16, 2008 #6

    malawi_glenn

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    _Mayday_ : you are right. I want to stress that the OP should have learned how to find out the number of atoms of certain element given the mass of the sample b4 he should get an excersice of this kind. And if he haven't, I could point him to a tutorial and that he must talk to his teacher. He must also show that he has made an effort, it is so simple to find out things my using google :P Now you gave him a keyword, he can google that and he will find out how to find the number of atoms of one kind in a sample given its mass.
     
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