Circular Proton Beam ( trying to replicate GEANT4 simulation)

Hello everyone, I would like to simulate a circular proton beam, like someone did previouslyon GEANT4, with this features:

/gps/particle proton
/gps/direction 0. 0. 1.

/gps/ene/type Gauss
/gps/ene/mono 147.8 MeV
/gps/ene/sigma 0.8 MeV

/gps/ene/sigma 0.9 MeV

/gps/pos/type Beam
/gps/pos/shape Circle
#/gps/pos/sigma_r 2.5 mm
/gps/pos/sigma_x 2.9 mm
/gps/pos/sigma_y 2.3 mm
/gps/pos/centre 0. 0. -150. cm

/gps/ang/type beam2d
/gps/ang/rot1 -1 0 0
/gps/ang/rot2 0 1 0
/gps/ang/sigma_x 3.21 mrad
/gps/ang/sigma_y 3.64 mrad.

The problem is I’m not sure if It’s possible to do it with FLUKA. The problem, basically, is given by the uncertainities on x and y of the circular beam. Is there a way to assign these uncertainities on FLUKA, maybe using source_newgen.f? Thanks in advance.

Dear @sclgnn92a07m20,

Yes, it is possible.
Have a look at the lecture on simple sources from the last beginners’ course and, if the built-in fuctionalities are not enough for you, have a look at the source routine lecture.
You can also find several relevant threads in the forum.