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Homework Help: Dark matter collisions with Xe on earth

  1. Nov 23, 2008 #1
    original question

    Assume that the density of dark matter near the earth is 0.3 GeV / cm3 and that the dark matter particle has a mass of 100 GeV and a velocity of 200 km/s. If the dark matter-nucleon cross section is 10^-44cm2 calculate how many events you would expect to see every year in a metre cubed volume of Xenon at room temperature.

    I have worked out that

    1) density of dark matter particles near earth is 3 particles per m^3
    2) the flux of the dark matter 6 * 10^5 m^-2 s^-1 passing through a m^3 of Xe
    3) that there are 1.668 *10^25 particles in a m^3 of xenon

    if the the cross section of dark matter 10^-44 cm^2

    How do i work out the number of collisions per second?
    Last edited: Nov 23, 2008
  2. jcsd
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