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Homework Help: Cross section of a S wave

  1. Feb 11, 2007 #1
    1. The problem statement, all variables and given/known data
    The total cross section of a S wave is given by the following equation
    Sigma=(pi/k)*(b^2)/((E-En)^2+(b/2)^2))
    prove that b is the width of the resonance.


    2. Relevant equations
    Nothing that is the only thing


    3. The attempt at a solution
    I already solved the question using basic calculation.
    For E=En i get the maximum of Sigma , for half of that maximum , i get a second degree equation of E, when solving it i get 2 solution representing that half maximum(E1 & E2) , the difference between E1 and E2 , E1-E2=b
    But I'm not really comfortable with the way i did it , I know i got the solution , but i'm looking for another way , something more to do with physics.
    idea anyone?
     
  2. jcsd
  3. Feb 13, 2007 #2

    Meir Achuz

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    You did it correctly. Somtimes physics depends on simple math.
     
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