769 / 1245
IAEA
Formula according to the ICRU Report No. 37.
with
N
A
= Avogadro’s constant
I
= mean excitation energy
Z
= atomic number of substance
=
E
K
/ (
m
e
c
2
)
A
= molar mass of substance
= density effect correction
r
0
= electron radius
m
e
c
2
= rest energy of the electron
=
v/c
v =
velocity of electron
c =
velocity of light
2.5 INTERACTION COEFFICIENTS: ELECTRONS
2.5.4 Mass stopping power for electrons and positrons