POPULATION OF HE 4(1)D MAGNETIC SUBLEVELS BY COLLISIONS WITH PROTONS AND MULTIPLY-CHARGED IONS IN THE INTERMEDIATE VELOCITY RANGE

We have investigated the collisional excitation of He by protons and multiply charged ions at intermediate velocities applying the optical method. The population of the magnetic sublevels of He 4(1)D has been determined using level-crossing techniques for a variety of projectiles with charges ranging from 1+ to 23+ and velocities between 1 au and 7 au. The relative excitation cross sections sigma(M)/sigma4(1)D of the ZeeMan substates turn out to be universal functions U(M)(upsilon2/q) of the projectile velocity upsilon and charge q. Total excitation cross sections of the 3(1)P, 4(1)S and the 4(1)D state are included for a discussion of the scaling relation sigma/q = f(upsilon2/q).