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Homework Help: Kinetic energy of an electron on the β spectrum?

  1. Nov 3, 2017 #1
    1. The problem statement, all variables and given/known data

    A 191Os nucleus decays via β- emission to an excited state of 191Ir at 171 keV. What is the maximum kinetic energy of the electron on the β spectrum?
    a) 0.134 MeV
    b) 0.143 MeV
    c) 0.171 MeV
    d) 1.859 MeV

    2. Relevant equations

    191 Os = 190.960928u
    191 Ir = 190.960591u

    (190.960928u - 190.960591u) * 931.5MeV/u = 0.3139 MeV

    0.3139 MeV - 0.171 MeV = 0.143 MeV

    3. The attempt at a solution

    I am unsure if my answer of 0.143 MeV is correct. In my notes it says the maximum kinetic energy is equal to the Q value of the reaction, so I wokred out the Q value above then subtracted the "excited state" value.
  2. jcsd
  3. Nov 3, 2017 #2


    User Avatar
    2017 Award

    Staff: Mentor

    That is right.
  4. Nov 5, 2017 #3
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