K-vacancy production in heavy-ion collisions. III.1sσexcitation

Abstract

We discuss $K$-vacancy production in the higher-$Z$ collision partner in very asymmetric heavy-ion collisions. In terms of an atomic model this process would be described as $1s$-vacancy production, but in terms of a molecular model it would be called $1s\sigma$-vacancy production. Experimental results from our work with 12-60-MeV Br, 200-330-MeV Kr, 15-80-MeV I, and 326-470-MeV Xe beams, and the work of others with lighter projectiles, are used for comparison with available theories and prescriptions for $K$-vacancy production. We discuss the binding correction model of Basbas et al., and semiempirical scaling law proposals made by Foster et al., Meyerhof et al., and Andersen et al. Since none of these prescriptions systematically reproduce the experimental $1s\sigma$-vacancy cross sections, we have developed a more detailed formula which stresses the transient united-atom formation during a heavy-ion collision. Other factors influencing $1s\sigma$-vacancy formation, such as Coulomb deflection, charge exchange, and electronic relativistic effects, are discussed.