K-Vacancy Production in Heavy-Ion-Atom Collisions at Small Impact Parameters

The probability P(b) of forming K vacancies in 60-MeV I + Ag collisions with center-of-mass scattering angles ¿cm between 20° and 144° was measured. The measured probability varies approximately as sin2¿cm, as predicted for the kinematic peak part of 2p¿-2p¿ rotatational coupling. We conclude that while the shape of P(b) indicates that 2p¿-2p¿ rotational coupling is important in the creation of K vacancies, the probability of creating the initial 2p¿ vacancy must be impact parameter dependent. In other collisions where a rise in P(b) has been observed at low impact parameters, it is possible that the rise is due not to a kinematic peak, but to a contribution from 1s¿ vacancy production.