Isotropic radiation beams randomly distributed along user defined range

Dear FLUKA experts,

Instead of a monochromatic beam, I want to introduce isotropic radiation beams that are placed in the void and are randomly sampled around a given radial range (from 0 to pi in my case, see red half-circle in the figure), or if a radial range cannot be given, around the whole void (so from 0 to 2pi).

Can this be done in FLUKA?

So for example, if I run 100,000 neutron particles, these are randomly distributed over the circle length from 0 to pi. In this case, should also a centre be defined toward which the particles are directed to?

In other words, this is much alike a GCR event. The reason why I am not using FLUKA’s GCR card (and the other necessary ones) is because I am using data from an external source for this and my case is on the Martian surface.

I looked at the documentation, in particular SPECSOUR and BEAMSPOT from the FLUKA Advanced source definitions lecture, but I am not sure if I’m going in the right direction with this for my case.

Many thanks in advance.

With kind regards,

Dear Kim,

you may want to look at the user source routines, here you can code any arbitrary source:

See the following lecture:

and the related exercises: FLUKA Beginner Online Training (31 May 2021 - 11 June 2021): Hands on - Source routine · Indico