BROADR adds temperature dependence to the pointwise cross
sections generated by the RECONR module (see UNRESR and PURR
for temperature dependence in the unresolved energy range).
It can also be used to rebroaden the results of a previous
BROADR run to a higher temperature.
In a material at temperature T, the target atoms and molecules are moving around randomly with a distribution of velocities given by the Maxwell-Boltzman function:
where α=M/(2kT). When a neutron moves through the material, it is the relative velocity between the neutron and the target nucleus that determines the proper cross section to use. We can define a single effective cross section for neutrons with velocity v by conserving the reaction rate:
BROADR uses methods based on early versions of Cullen's SIGMA1 code to compute these effective cross sections for linear-linear representations of the basic reaction cross sections. The basic cross sections are obtained from a PENDF tape generated by RECONR or produced in a previous BROADR run. The Doppler-broadened effective cross sections are written out as a multi-temperature PENDF tape.
The following is an example of a simple BROADR run to
Doppler broaden the results of a previous RECONR run (on
20 21 22 125 1/ .001/ 300/ 0/
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|23 January 2013||T-2 Nuclear Information Serviceemail@example.com|