Angular Divergence Reset in beam2D Source #734
Description
GATE version: 8.2
Component: beam2D source configuration
Summary:
When using the beam2D source type, setting the angular distribution parameters (sigma_x, sigma_y) followed by a set_direction command causes the angular values to be silently reset to their defaults. This results in incorrect divergence being applied in simulations, particularly when asymmetric divergence is intended.
Expected Behaviour:
Setting sigma_x and sigma_y should persist regardless of the order in which set_direction is called.
Observed Behaviour:
If sigma_x/y are set before set_direction, they are reset to default values.
If set_direction is called after setting angular parameters, the direction is preserved but the divergence is lost.
This issue does not occur with beamIso.
Impact:
Simulations using beam2D with asymmetric divergence may be unintentionally run with incorrect beam parameters, affecting beam shape and dose distribution.