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Homework Help: Cross sections and lifetimes

  1. Feb 25, 2010 #1


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    1. The problem statement, all variables and given/known data
    In the attached file, I need some help with questions 3 and 4.

    2. Relevant equations

    3. The attempt at a solution
    For question 4, I get the next answers:
    a. The flux is given by:
    [tex]f=\frac{v_{\nu}\rho}{m}[/tex] where m is the mass of the iron nucleus, rho is the iron density and v_{\nu} is the nuetrino speed.

    b. If I get this right then [tex]\frac{N_{events}}{N_{particles}}=\frac{\sigma_{\nu}f dx}{v_{\nu}}[/tex], and the number of scattered nuetrinos is N(x) times this fraction, i.e:
    [tex] dN= \frac{\sigma_{\nu}f dx}{v_{\nu}}N[/tex].

    c. easy as well, just identifying the above constant minus a sign with lambda.

    d. Here is where I am findining it hard, I need to multiply sigma_{\nu} with some constant in order to eliminate the dimensions of energy in this cross section, I don't know how to do it, any hints as to how reconcile this?

    The other questions are plug-and-calculate which aren't hard.

    For question 3, I am not sure how to answer this question, any hints?

    Thanks in advance.
  2. jcsd
  3. Feb 25, 2010 #2


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    Gold Member

    The attachment.

    Attached Files:

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