  We consider high-energy quasifree single- and two-proton knockout reactions
induced by electrons and protons and address the question what target-nucleus
densities can be effectively probed after correcting for nuclear attenuation
(initial- and final-state interactions). Our calculations refer to ejected
proton kinetic energies of 1.5 GeV, the reactions (e,e'p), (\gamma,pp) and
(p,2p) and a carbon target. It is shown that each of the three reactions is
characterized by a distinctive sensitivity to the density of the target
nucleus. The bulk of the (\gamma,pp) strength stems from the high-density
regions in the deep nuclear interior. Despite the strong attenuation, sizable
densities can be probed by (p,2p) provided that the energy resolution allows
one to pick nucleons from s orbits. The effective mean densities that can be
probed in high-energy (e,e'p) are of the order of 30-50% of the nuclear
saturation density.
