I am able to model spherical source using CALL RACO(TXX, TYY, TZZ) function as per old format of source.f routine.

However. there is no document on modelling of a spherical volume source using source_newgen.f.
Kindly suggest me how to model a spherical volume source using source_newgen.f.

the RACO subroutine is still usable in the source_newgen.f user routine without any issues. But if you prefer you can use the wrapper subroutine sample_isotropic_direction.

Thank you for your reply. However, as per my understanding,
call sample_isotropic_direction( direction_cosx, direction_cosy, direction_cosz ) will sample the isotropic emission of the particles.

I want to model a spherical volume source of radius 2.5 cm and emission is isotropic. How to do this?

If you replace the direction_cosx, â€¦ variables with the coordinate ones in sample_isotropic_direction, then you get a sampling on the surface of a sphere.
Then you can call it again, now with the variables for the directions, to get the isotropic source distribution.

My source is not uniform random distribution over the surface of the sphere. It is uniform random distribution of source particles throughout the entire volume of the the sphere.
Co-ordinate sampling is something like below: