Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Interaction of radiation with matter

  1. Sep 29, 2013 #1
    1. Problem statement

    i am trying to calculate the momentum and energy of the products in the reaction

    7Be4 + e -----> 7Li3 + neutrino

    2. Relavant equations

    p = mv
    mass of 7Be = 7.016929 u
    mass of 7Li = 7.016004 u


    3. The attempt at a solution

    i know that after the electron capture, the neutrino and the daughter nucleas will move in opposite directions with the same momentum magnitude, and so form momentum coservation

    mv(Li) = mv(neutrino)

    but how do i go about findig the 'v' of Lithium in order to calculate its momentum, mv. the question does not give any info on 'v'. ? Do i even need the value of 'v' or not. So that i can then put that 'v' into the equation of finding the energy of the daughter nucleas as:

    1/2 * m(Li)*v^2(Li) = ( m(neutrino)/m(Li) ) * E(neutrino)

    am i actually in the right path, i would greatly appreciate any directions?
     
  2. jcsd
  3. Sep 29, 2013 #2

    mfb

    User Avatar
    Insights Author
    2015 Award

    Staff: Mentor

    Where do you use energy conservation? It is important here, together with momentum conservation.

    It does not have to.

    The neutrino is ultrarelativistic, you cannot use the nonrelativistic momentum. Treat it like photons instead. Do you know the energy-momentum relation for photons?
     
  4. Sep 29, 2013 #3
    * The momentum of the neutrino is not going to be mv because it will be a relativistic particle.

    * Did you apply energy conservation?
     
  5. Sep 29, 2013 #4
    ohhh, Thank you, it's E^2 = (pc)^2 + (m0*c^2)^2

    will apply it , hadn't considered the relativistic issue....
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Interaction of radiation with matter
Loading...