SPOTBEAM Usage and Errors

I am trying to use the SPOTBEAM source in a very simple test case. Based on what I understand from the documentation, I believe I have implemented it correctly but the simulation does not produce two simultaneous input beams. I have initiated it with the SPECSOUR card and setting the “Type” to BEAMSPOT.

Furthermore, based on the Flair manual, any SPOT card entries left blank should pull their values from the BEAM, BEAMPOS, etc. cards respectfully. I have not found this to be the case. For example, without using a SPOTDIR card, the direction is not being pulled from the BEAMPOS card.

Attached is my .flair file.

LattPhse_Test.flair (3.6 KB)

Dear Dirk,

Thank you for letting us now about your issue. The problem in you case is that the weight of the spots are not set. Unfortunately no warning/error message is generated to notify the user.

After setting the Spot Weight for both of the beams. FLUKA creates the two beams and a direction specified on the BEAMPOS card is taken if no SPOTDIR card is present for the given beam.

Please let us know, if this solves all of your issues.


It did solve my issue.

A few things of note:

  1. For BEAMSPOT sampling with the Sequentially equal option, the number of input particles must be an exact multiple of the beam spots. The manual SPECSOUR, BEAMSPOT entry doesn’t mention this but it would be useful as I got an error otherwise.

  2. You are correct, once I added the spot weights, the simulation did run with the direction pulled from the BEAMPOS card. However, the SPOTBEAM arrows in the geometry viewer do reflect the correct direction unless I added SPOTDIR as can be seen in the attached .flair file.

LattPhse_Test.flair (3.6 KB)

Thanks for reporting. I am working on the correction on the display