Problem 2557

Hi,

Is your "point2" pre-step point or post-step point?
How do you get the "point2" pointer?

In general, a step is limited by all the volume boundaries not only in the mass world but also in a parallel world. And the mesh volume is created in a dedicated parallel world.

Dear expert,

Thanks very much for your reply! I replied directly in the email. I'm not sure if you received my reply. Here it is:

I'm using post-step point. For example in the stepping action:

  // Collect particles at target exit

  bool is_amor_leave = 0;

  if (l_amor>0 && statusP2==fGeomBoundary && VolNameP2=="TargetDetector" && pzP2>0){
    //if (zP2 == z_amor_leave)
      is_amor_leave = 1;
  }

where electrons hit a target and I collect positrons with a detector placed 0.001 mm after the target.

The meshes are overlapped with the target.

The number of positrons I obtained with meshes on is more than the number with meshes off, even when the detector is 1 mm downstream the meshes, which I can not understand.

And when I wanted to save the particles that enter the boundary of my target, it is also a problem.

Best,
Yongke

Dear experts,

May I ask if there is any update on this topic?

Thanks very much!

Best,
Yongke

Hi,
I could not reproduce the issue. The code you are referring has not been changed since version 10.6. Meanwhile, there are some changes in electromagnetic physics in the treatment of range cut near the volume boundary. Could you please provide us a simple test code that generates this problem?

Also, please specify which physics list (EM physics option in particular) you are using.

Sorry but one more question. You wrote in the discussion forum
> The problem is that when I updated Geant4 from 10 to 11, the positron 
> yield at the target exit gets higher. 
Could you be more specific which exact version in 10 series you used before?

Dear expert,

It's version 10.7, if I remember correctly, that worked well. Though I remember there was also a difference in the positron yield (ratio of positrons to electrons) when using or not using scoring mesh, the difference was not so large.

But now when I use version 11.1, the difference in the yield of using or not using scoring mesh is much larger. I don't know which yield is correct. This is the main problem.

Another problem (maybe the same problem) is that, as I said earlier, when I use scoring mesh and when I try to count particles at the target boundary (from World to target), the meshes contribute to this boundary and the counting is totally wrong.

Thanks very much in advance!

Let me know if you need more information.

Best,
Yongke

As I wrote earlier, please inform us which physics (in particular which EM physics option) you use.
Also, we appreciate it if you could provide us a sample code that reproduce the issue.

Sorry I didn't notice the other comments. 

Sure! I will prepare a test code for you.