
#1
Nov2709, 12:04 PM

P: 2

The nonrelativistic Bethe stopping power function contains the constant 2*pi*N*e^4 where N is Avogadro's number and e is the electron charge. In the literature, this constant is often calculated to be 78,500. If calculate the constant, I get 606,235 (=2 * pi * 6.02214179E+23 mol^1 *(1.602176487E19 C)^4). Does anybody know what my mistake is?
Thank you. 



#2
Nov2709, 02:26 PM

P: 4,664

I usually use the Bethe Bloch equation in the form
http://en.wikipedia.org/wiki/Bethe_formula and substitute e^{2}/(4 pi ε_{0}) = r_{e} m_{e}c^{2} where r_{e} is the classical electron radius (2.818 x 10^{13} cm) and m_{e}c^{2} is the electron rest mass which is 511,000 eV (one of which cancels in the denominator) See my posts #8 and #9 in thread http://www.physicsforums.com/showthread.php?t=332899 Bob S 



#3
Nov2709, 05:13 PM

P: 2

Thank you. That helped.



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