An intense and stable continuous beam of SO radicals has been produced with a microwave-discharge source operating in the Torr range in mixtures of SO2 with various gases. The free-radical beam emerging from the plasma source is velocity analyzed by a mechanical velocity selector and detected by a quadrupole mass filter. Stern-Gerlach magnetic analysis shows SO radicals mainly in the electronic ground state (3) Sigma(-) with a rotationally hot distribution and provides an upper limit (less than or equal to 7%) on the concentration of electronic metastable states. Total integral cross-section measurements as a function of velocity in the range 0.9-2.4 km.s(-1) for the scattering of ground-state SO radicals by Ne, Ar, and Kr have also been performed. The analysis of experimental data (cross sections and their velocity dependence, which exhibits glory interference patterns) allows a characterization of the interaction potential features for the investigated systems. Use of a correlation rule leads to an estimate of the average polarizability of the SO molecule and also of the potential features for SO-He and SO-Xe.