5.15. [ Elastic Option ] section

In this section, you can set some parameters for user defined elastic option for low energy neutrons. By this function, you can change angle distributions of elastic collisions of data based neutron reactions. We prepare two sample routines, usrelst1.f and usrelst2.f. You can choose one of these two by usrelst=1, 2 in the parameter section.

You should define the regions to which this function is applied and 4 parameters as follows:

[ Elastic Option ]
  reg   c1    c2    c3    c4
  1     5     1     3.3   0.4
  2     1     1     1.1   0.7
  3     3     1     0.3   0.8
  ...   ...   ...   ...   ...
  ...   ...   ...   ...   ...

If you want to replace the order of region number (reg), (c1 c2 c3 c4), set as reg c3 c2 c1 c4. You can use the skip operator non. You can use the format { 4 - 7 }, but the ( { 4 - 7 } 9 10 ) format cannot be used.

The sample routine of usrelst1.f is for Bragg scattering based on the data base, and usrelst2.f for any type of angular distribution described by an analytic formula.