Data Representation

The cross sections vs energy generated by THERMR are put into File 3 as simple tabulations using the MT number (or numbers) requested by the user. The energy-angle distributions appear as normalized distributions in File 6. For a specified grid of incident energies, a distribution vs secondary energy is given on a grid chosen to represent the actual angle-integrated function to a specified accuracy. At each secondary energy, a specified number of discrete scattering cosines is given with a predetermined set of probability values. This format allows for easy sampling in a Monte Carlo code, and it can also produce good values for Legendre coefficients when needed.

As an example of the THERMR run, consider the following input deck:

      26 22 23
      1065 1306 8 1 4 1 1 229 0
      .01 1.2

To understand this input, compare it with the THERMR input instructions. This run is for carbon from ENDF/B-V (MAT=1306). Thermal MAT=1065 is graphite from the thermal ENDF file Tape 322 mounted on unit 26. The results will be written on the new PENDF tape on unit 23 using MT=229 and 230.


23 January 2013 T-2 Nuclear Information Service