Usage of ROT-DEFINi Card

Dear FLUKA experts,

While using the attached input in FLUKA, I got some confusing results. In this, I am using two ROT-DEFINI cards, namely, rot 1 and rot 2. rot 1 is used to transform a detector (det) and rot 2 is used to transform the bodies (aw and bw). I am performing scoring using DETECT card (along with DETGEB) and USRBIN. The source is 662keV photons given using BEAM card.

I have the following problems:

  1. When I introduced dx, dy and dz in ROT-DEFINI card for rot1, my simulation finished with errors. However, it worked well when I used rotation alone in ROT-DEFINI (implemented using transform directives) and dx,dy,dz using start/end translat directives.

  2. For rot2: What geometry viewer shows in the attached ‘sample.flair’ file is precisely what I am intending to make. However, the same geometry can be obtained in two ways;

    a) Define translations of dx =18 and dy=-20 using start and end translat cards

    b) Define dx=18 and dy=-20 in ROT-DEFINI cards with zero rotation. I need to make a rotation of these bodies in further studies. That’s why I kept the ROT-DEFINI card even if its angle of rotation is zero in the attached file.

Both a) and b) show same geometry in the viewer. In both cases, the beam position was also the same. However, USRBIN and DETECT scoring turned out to be quite different. I am attaching the USRBIN superimposed on geometry for the two cases. Why are the BEAM-PART distribution different although the geometry looks same?

It will be really helpful if someone can explain me the difference.


sample.inp (3.0 KB)
sample.flair (7.6 KB)

Dear @cbala ,
Thank you for your message. I am trying to understand the problems you encounter:

  1. For the first error, could you upload the exact cases in which you find these problems? I have tried to replicate without success.
  2. By running different examples, it seems your problem may be in the lack of dz value for your translation. These translations are directives, not cards, so they may not have values by default. After setting dz=0, both the translation directive and the ROT-DEFINI card yield the same results to me.

Let me know if this is helpful.

Best regards,

Mario Sacristan


Dear @msacrist,

Thank you very much for your message.
Setting dz=0 solved my problem, indeed. I have assumed that the directives would take defaults like the cards. For me as well, the first error has vanished now! And I think it was also due to the vacant value in the directive, which I might have changed during my trials to figure out a solution.
Thanks for helping here.