Multiple beams using source routine

Advanced Features and User Routines
1

Dear FLUKA and FLAIR experts,

I need some clarification.

Let’s say I have 3 different particles in a beam.

Using my source routine I would have something like this

My questions are:

1.- For every primary, I would have only one particle at random taking into account its probability. This process would be similar to what SPOTBEAM card does using spot weights. Is this correct?

2.- Is there a way to have multiple particles at the same time instead of one per primary in my simulation? Each kind of particle having a different distribution defined by source.f

Thank you in advance.

Best Regards,
Carlos

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2

Dear Carlos,

  1. Yes, this it the same idea as the spot weights.

  2. It is possible to have multiple primaries in a single event in FLUKA. However, if you are not utilizing event-by-event scorings (EVENTBIN, DETECT, etc.), the results will be the same as having only one primary particle in an event.

Cheers,
David

3

Dear David,

Thank you for your reply.

To your second point. I am using EVENTBIN for scoring, so I want to be able to have multiple primaries per event, but I am unable to do so.

Could you point me on how to do it?

Best Regards,
Carlos

4

Dear Carlos,

you need to duplicate the main part of the source routine to put another particle into the stack.

For example see: source.f (15.0 KB)
This user routine will add a proton and an electron to the stack with different energies and starting points.

Cheers,
David

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5

Dear David,

I am bit unfamiliar with source.f syntaxis. Is there a way to add to the stack using source_newgen.f syntaxis?

Best Regards,
Carlos

6

Dear Carlos,

technically it is possible to use the source_newgen.f user routine. However with source_newgen.f you can sample only from one histogram, without significant changes.

You can find the description of the source.f user routine here: 13.2.20} source.f: user-written source | FLUKA

Cheers,
David

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