Radii of halo nuclei from cross section measurements.

The root mean square matter radii of halo nuclei provide a basic measure in constructing, constraining, and assessing theoretical models of halo structures. We consider corrections to static density ~optical limit! Glauber model calculations of reaction cross sections of such nuclei at high energy giving careful consideration to their intrinsic few-body structure and the adiabatic nature of the halo nucleus-target interaction. We take as important examples the loosely bound twoand three-body systems Be, He, Li, and Be. The contribution of the valence particles to the calculated reaction cross sections are shown to be significantly reduced, requiring increased halo radii to reproduce experimental data. The implications of these changes for structure models of extended twoand three-body systems are discussed. @S0556-2813~96!04810-8#