Is it possible to bias the angular emissions from radioactive source?

Hi All,

I am using RDM to simulate decay of radioactive decays. The macro is similar to test1 here.

The simulation takes a while since all the particles/gammas emitted by the radionuclide are emitted isotopically (4pi). All of my detectors are on one side of the source and I am wondering if it is possible to limit the emissions to only desired angle only, e.g., 2pi?