Aa. Sakharuk et V. Zelevinsky, QUASI-ELASTIC KNOCKOUT OF ALPHA-CLUSTER BY INTERMEDIATE-ENERGY PROTONS - SIGNATURES OF VIRTUALLY EXCITED-STATES, Physical review. C. Nuclear physics, 55(1), 1997, pp. 302-317
The long-standing problem of experimental signatures for clustering ef
fects in light nuclei is discussed for the conditions corresponding to
a recent experiment. The specific reaction C-12(p,p'alpha)Be-8 at inc
ident proton energy 300 MeV and fixed proton and alpha-particle angles
near the quasielastic peak is discussed. The Glauber approximation wi
th a simple parametrization of the elementary nucleon-nucleon amplitud
e is used for calculating the cross section. The main emphasis is on t
he existence of virtually excited cluster configurations and their man
ifestation in experimental observables. The shell model wave function
of the C-12 ground state is used to extract the weights of excited clu
ster components and to calculate their contributions to the cross sect
ion. The presence of several excited components and their complicated
interference influence the shape and the height of the quasielastic pe
ak; the change can reach an order of magnitude. It is shown that the c
ross section for cluster emission with the excitation of Be-8 into the
first excited 2(+) state is small as compared to the process leaving
Be-8 in its ground state.