Two-electron processes in the ionization of H2 and D2 by fast protons

Measurements on dissociative ionization of H2 and D2 by fast (16 endash 25 MeV) protons are carried out in an effort to understand two-electron processes in collisional ionization. The high velocity limit of the ratio of cross sections, R, of two-electron processes to one-electron processes obtained from these measurements along with earlier data is used to obtain a universal scaling law for R as a function of projectile charge and energy, irrespective of the sign of the projectile charge. copyright 1996 The American Physical Society