Dear @zamirkhanyan,
“First of all, could you please explain to me how can I make the picture you attached?”
Sure, you need to use this card:
This will dump a file that you can use to plot in the Geometry the track of your particles.
Follow the steps in the 5th post of this Thread:
“Now I try to focus the beam with thin lenses (increasing the field strength), but still keep the asymmetry of the beam at the focal point position.”
After discussing with some experts, it seems that the problem is due to the fact that when you are using large beam size, some of those particles are in regions of very high field. Those are the particles that are deviated, as we observed in the plot I attached in my previous post, which are deviated through a dipolar field component. That seems to be the reason why some of the particles are focused on a different focal point.
So, it seems that the the RMS limit depends on the beam energy and the field intensity. I could not obtain a way to quantify this limits for the moment. But I let you know If I find it.
As a final comment, I wanted to add that this problem is actually
related to beam optics, and FLUKA is not really intended for this.
Having said this, you understand that this topic is out of scope for this forum
and we recommend you to use a beam optics tool.
Best,
André