5.9. [ Mat Time Change ] section

By this section, you can change the material of certain cells to the other material as a function of time. This function is useful to describe a shutter of beam line, T0 chopper and the other devices for neutron optics. The unit of time is nsec.

The format is as follows.

[ Mat Time Change ]
  mat   time    change
  1     50.0    11
  2     100.0   12
  3     1000.0  0
  ...   ...     ...
  ...   ...     ...

In the above example, the material 1 is changed to material 11 at t=50.0 nsec, 2 to 12 at 100 nsec and 3 to void at 1000 nsec. If you want to replace the order of the initial material (mat), time (time) and the final material (change), set as mat change time. You can use the skip operator non. These three columns are always necessary to define the mat time change function.