VersionXGEN_Notes.txt

Notes on changes for MatMCNP Version XGEN
 - February 2021
-------------------------------

This modification allows the user to create material files for use with the xgen program. XGEN
is a utility code for producing continuous energy electron/photon cross sections for use with the
Integrated Tiger Series (ITS) code system. This modification to MatMCNP does not change any of the 
calculations previously discussed and verified. It is simply a new format to output the results.

To invoke the XGEN input generation, simply replace the material number intended for the MCNP
material number with "xgen". The xgen input uses a default energy of 1.0 MeV which must be changed if
your ITS problem has a different maximum energy. The density output in the xgen input file will need
verification if you are using low density (< 1.0e-5 g/cc) materials.

With these changes, MatMCNP expects no arguments, 2 arguments, or 3 arguments.
 (1) No arguments on the command line:
     - Input file:  matmcnp.inp
     - Output file: matmcnp.out
     - XGEN input:  matxgen.inp

 (2) Two arguments on the command line:
     - Input file:  First argument
     - Output file: Second argument
     - XGEN input:  matxgen.inp

 (3) Three arguments on the command line:
     - Input file:  First argument
     - Output file: Second argument
     - XGEN input:  Third argument

An example using Dry Air has been added.

New Files:
(1) VersionXGEN_Notes.txt - This file
(2) DryAir_NoXGEN.inp - An input file using original MatMCNP input format
(3) DryAir_NoXGEN.out - Output file from (2)
(4) DryAir_XGEN.inp - A MatMCNP input file that will generate an xgen input
(5) DryAir_XGEN.out - Output file from (4)
(6) XGEN_DryAir.inp - A file that can be used by xgen to generate cross sections for ITS
(7) bin/MatMCNP_vXGEN.exe - A Windows executable built with gfortran using the makefile in /source