518 / 1224
The method
The importance of f(E):
The spectral weighting factor connects photon fluence to energy fluence
at any point of a geometry and hence depends on the actual geometry and
its physical properties.
However, as G increases, and ΔΕ
G
become narrow, the energy group cross sections
μ
t,g
, μ
s,g
, become constant approximations of the continuous μ
t
(E), μ
s
(E)
and do not depend heavily on f(E).
This means that generic multi group cross sections (of ΔΕ
G
<<) are used with
analytic
or semi-analytic f(E) appropriate for the problem at hand
.
=
=
E
dEEf
E
f r
Er
1 )
(
,
) ( )(
) ,
(