Projectile-breakup and transfer-reemission reactions in the 12C+20Ne system.

The /sup 12/C(/sup 20/Ne,..cap alpha.. /sup 16/O/sub g//sub .//sub s//sub .//sup 12/C/sub g//sub .//sub s/., /sup 12/C(/sup 20/Ne,..cap alpha.. /sup 20/Ne)/sup 8/Be/sub g.s./, and /sup 12/C(/sup 20/Ne,..cap alpha.. /sup 12/C)/sup 16/O/sup */ reactions at E( /sup 20/Ne) = 157 MeV were studied by using position-sensitive telescopes. It was established that ..cap alpha..-/sup 16/O coincidences in the first reaction result not only from sequential breakup of the projectile, but also from the transfer-reemission process /sup 12/C/sub g.s./C(/sup 20/Be,/sup 16/O/sub g.s./)/sup 16/O/sup */..--> cap alpha..+ /sup 12/ Distributions of the excitation energy in the primary reaction products were deduced by calculating respective branching ratios with a Hauser-Feshbach statistical-decay code. It was found that excitation energy is generated in mass transfer reactions quite asymmetrically: it is mostly concentrated in the nucleus that acquires mass, while the ''donor'' nucleus, on the average, remains cold. These results clearly support the basic concept of ''spectator'' models of heavy-ion reactions.