Dear experts,
How to calculate the time required for two groups of photons to travel along the wavelength-shifting fiber and reach their respective endpoints？
Dear XIONG BANGPING,
It is not possible to score the timing of particles using built-in scoring with FLUKA. I recommend you use the MGDRAW routine called by the USERDUMP card. You will want to save the track age (variable ATRACK) when it crosses the boundary of the target regions (calling the entry BXDRAW).