7. CompositionsΒΆ
To calcualte nuclear concentrations are changed by induced external particle
field is necesserary to know the value of reactions rate.
Reactions rate could be expressed as
external flux [particle/sec/cm^2] x cross-section[cm^2].
To describe that values multigroup energy model are used in the OpenBPS. Every
energy-dependent distribution with dimension (NG) should be presented by
energy discretization array with a size NG + 1. Meantime it could be a
number of values of flux/cross-sections/reaction-rates. For example:
<energy ng="4">0.0252 0.215 0.465 1.0 2.15</energy>
<energy ng="1">0.0252 2.15</energy>
<xslibs ng="1" typex="cs">
</xslibs>
<flux ng="4">1.0 0.00000E+00 0.00000E+00 0.00000E+00</flux>
Data of <flux> matches to energy discretization with ng="4" meanwhile
<xslibs> to one with ng="1". To bind external field interactions data
with nuclear concentration, composition attribute name should be equal to
the same attribute in materials description.
Note: For neutron induced radiation it is very important to have
<flux>or normed<spectrum>array to calculate right fraction of fission product yield which are energy dependent too.