HIDDEN WORLD OF VIRTUALLY EXCITED CLUSTERS IN ATOMIC-NUCLEI AND ITS POSSIBLE OBSERVATION IN QUASI-ELASTIC KNOCKOUT OF CLUSTERS BY 1 GEV PROTONS

A new kind of cluster quasielastic knockout experiment is proposed based on the distorted wave impulse approximation calculation which uses Glauber-Sitenko multiple scattering theory and takes into account deexcitation of virtual excited clusters in the nucleus. Elements of general formalism are presented, including the discussion of the difference between ''fast'' and ''slow'' cluster processes. The reaction C-12(p, palpha)Be-8 is considered in detail. It shows a strong dependence of the ''effective momentum distribution'' of knocked-out cluster on both the scattering angle of fast proton and orientation angles of recoil momentum q with respect to the direction of the incident beam and to the scattering plane of a fast proton (i.e., THETA(q) and phi(q) anisotropies). Experiments of this kind are desirable also for electron-induced cluster knockout. Finally, the possibility of observing THETA(q) and phi(q) anisotropies in H-2(e, e'p)N* and H-1(e, e'pi+)n reactions at a few GeV energies due to the quark deexcitation effects is discussed.