THE EGS5 CODE SYSTEM

X
Z
ω
k
0
O
e
0
Y
Figure 2.25: Direction of k ⃗ 0 and ⃗e 0 after two rotations by A −1 .
⃗e z , another rotation along the z-axis is necessary to make ⃗e 0 ‖ ⃗e x .
While ⃗ k 0 is already parallel to
where
⎛
cos ω − sin ω
⎞
0
B = ⎝ sin ω cos ω 0 ⎠ . (2.445)
0 0 1
Limitations of the present code for modeling linearly polarized photon scattering
• Circularly polarized photon scattering is ignored and elliptically polarized photon scattering
is treated as partially linearly polarized photon scattering.
• Characteristic x-rays and bremsstrahlung photons are assumed to be unpolarized.
The formulas used in each simulation mode are summarized in Table 2.9.
2.20 Electron Impact Ionization
Because of the interest in modeling the generation in the production of characteristic radiation,
it is desirable to treat explicit δ-ray collisions involving inner shells atomic electrons. Inelastic
electron scattering collisions which result in the ejection of a bound atomic electron is typically
called electron impact ionization (EII), and a modification to EGS4 by Namito et al. [120] allowing
the treatment of K-shell electron impact ionization has been retained in EGS5. Six different cross
sections describing EII are available, as given below. A detail discussion of the cross sections and
a guide for selecting the most appropriate one for given applications can be found in [120].
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