In some cases, when outputs (position, energy, direction cosine) of mgdrawBDX are not enough to get good statistics in a two step process, writing a probability distribution using USRBDX can be an alternative way. For each solid angle (either in radian or degree) bin, we get energy distribution. In this context, I am not aware how these solid angles are defined (is it with respect to the origin of the geometry ? ) or how these solid angles are related to the direction cosines (like we get from mgdrawBDX output) . Can you please provide some insight ?
USRBDX scorings can be used to score double differential particle distributions across a boundary surface. This double-differential is in energy and angle. The angle is defined with respect to the normal of the boundary surface between 2 adjacent regions. The angular distribution is intended as the distributions in the solid angle with (1-cos(theta)). Theta is the angle between the particle trajectory and the normal to the boundary at the point of crossing.
Thank you @cimmino for the explanation. So from USRBDX output, position sampling is not possible right? , since if two particles at different position are entering a boundary (let’s say a sphere) with same angle with the normal drawn at their respective position, they will be registered in the same angular bin, right ??