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Homework Help: Scattering experiment assymetry and probability

  1. Sep 28, 2011 #1
    1. The problem statement, all variables and given/known data

    In a scattering experiment to measure the polarization of an elementary particle, a total of N = 1000 particles was scattered from a target. Of these, 670 were observed to scatter right and 330 to scatter left. Assume there is no uncertainty in N = Nr + Nl

    a) based on the experimental estimate of the probability, what is the uncertainty in Nr and Nl

    b) the asymmetry parameter is defined as A = (Nr - Nl)/(Nr + Nl). calculate the assymetry and it's uncertainty

    c) assume that the asymmetry has been predicted to be A = 0.4 and recalculate a) and b)

    2. Relevant equations

    binomial distribution

    PB(x;n,p) = (n x)pxqn-x

    mu = np sigma^2 = np(1-p)

    gaussian distribution

    poisson distribution

    3. The attempt at a solution

    a) p = 1/2
    N = 1000
    using sigma equation sigma = +- 15.8 for both Nr and Nl

    b) A = (670-330)/1000 = 0.34

    don't know how to find A's uncertainty

    c) found Nr = 700 and Nl = 300 error in both is still 15.8

    don't know A's again...

    please help
  2. jcsd
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