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Bethe formula question

  1. Jul 2, 2009 #1
    Im trying to use the Bethe formula (http://en.wikipedia.org/wiki/Bethe_formula) to find dE/dx for a particle through a material, but Im not getting the units to work out. In the part of the formula with (e^2/4PiEpsilon)^2, how should I convert this correctly? Those units are J*m, so can I just multiply by 100 to get it to J*cm and divide by 1x10^-6 to get it into MeV*cm?
  2. jcsd
  3. Jul 2, 2009 #2
    At first glance, wikipedia's formula looks suspicious, although they may be equivalent, I always use : the particle data book
    You may find your coefficient in table 27.1 if you really want wikipedia's formula.
  4. Jul 2, 2009 #3
    Thanks, ill use that. The one thing Im not sure of is the delta part of that equation. How do I figure out what to use for delta(beta gamma)?
  5. Jul 2, 2009 #4
    If you need this term at high energy, it is defined (and discussed) in 27.2.2
    Also, look at "without delta" curve label in 27.1
    For [itex]\beta\gamma[/itex]<10 the effect is rather small
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