<!-- material interactions file -->
<material_interactions>
 
<!-- cosine law, 40% of particles -->
<surface_hit source="O+" target="SS">
<product>O</product>
<model>cosine</model>
<prob>0.4</prob>
<c_accom>0.5</c_accom>
<c_rest>0.9</c_rest>
</surface_hit>

<!-- specular reflection, 20$ of particles -->
<surface_hit source="O+" target="SS">
<product>O</product>
<model>specular</model>
<prob>0.2</prob>
<c_accom>0</c_accom>
<c_rest>1.0</c_rest>
</surface_hit>

</material_interactions>