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Free neutron decay

  1. Jun 18, 2009 #1
    I was reading a blog where someone stated that the decay of a free neutron is characterized by a 'mean lifetime' but not by a half-life. They went on to indicate that the decay time is not random (in the sense that leads to a true half life) but rather most decay at the mean lifetime (said to be about 15 minutes), and very very few decay at times shorter or longer than this. So if you had a collection of neutrons, they would all be gone (decayed) shortly after the 15 minutes went by (as opposed to the half, then quarter, then 1/8... sequence seen in a half life situation). Is this right? How could that be true, unless the individual neutron "knows" how old it is??
  2. jcsd
  3. Jun 18, 2009 #2
    Hi there,

    You read a bunch of baloney. Free neutrons acts in exactly the same way as any other radioactive material. They will not decay all at once, but at a certain rate. The "mean-lifetime" is sometimes used to describe radioactive material, which is closely related to the half-life.

    For the rest, you seem to understand it in the right way.

  4. Jun 18, 2009 #3
    The free neutron free lifetime (the 1/e lifetime) is τ = 885.7 seconds. The probability of decaying at time t is proportional to
    P(t) = e-t/τ

    α β γ δ ε ζ η θ ι κ λ μ ν ξ ο π ρ ς σ τ υ φ χ ψ ω
  5. Jun 18, 2009 #4
    Thanks -
    The guy on the other blog has since recanted & apologized for blathering.
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