Double ionization of helium by high-velocity U90+ ions.

摘要: Double ionization of helium is investigated for 60-, 120-, and 420-MeV/u ({ital v}/{ital c}=0.34--0.72)U{sup 90+}-ion impact. The measured double-to-single ratios indicate that, even these very high velocities, double the He target results predominantly from independent interactions projectile with both electrons. It concluded that asymptotic high-velocity regime one-step (i.e., shakeoff'') has not yet been reached U{sup 90+} projectiles at 420 MeV/u, and, in fact, cannot be {ital q}{approx gt}7, thereby verifying ionic charge fully as important velocity determining importance a given mechanism.